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Revised edition by
With drawings by Crispin Fisher

9=tsp;t1<d Woodpecker


First published 1974 by T & AD Poyser Ltd

Print-on-demand and digital editions published 2010 by T & AD Poyser,
Copyright 1974 by T & AD Poyser
ISBN (print) 978-1-4081-3866-3
ISBN (epub) 978-1-4081-3867-0
ISBN (e-pdf) 978-1-4081-3865-6
any form or by any means photographic, electronic or mechanical, including
photocopying, recording, taping or information storage or retrieval systems without
permission of the publishers.

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From the Preface to the 1940 edition

Preface to the 1974 edition


Note on the illustrations


Introducing the birdwatcher to the bird


2 Arranging the birds


3 The tools of bird watching


4 Migration


5 Where birds live


6 The numbers of birds


7 Disappearance and defiance


8 How birds recognise one another


9 Territory, courtship and the breeding cycle



What you can do




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List of plates
Puffin with coloured plastic identity ring

Gannet colony on Grassholm, off Pembroke coast

Mist nets in a woodland clearing

A chardonneret garden trap

Extracting a bird from the mist net

Holding the bird correctly

Applying the ring with special pliers

Wedge-shaped nestbox for Treecreepers

Open-fronted boxes for Pied Wagtails


A male Robin attacking a stuffed bird


Blowing aside the feathers to reveal a female Hawfinch's

brood patch


Ringed Plover settling on eggs


Bird rings of several sizes


Common Tern chicks camouflaged

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From the Preface to the 1940 edition

Some people might consider an apology necessary for the appearance
of a book about birds at a time when Britain is fighting for its own and
many other lives. I make no such apology. Birds are part of the heritage
we are fighting for. After this war ordinary people are going to have a
better time than they have had; they are going to get about more; they
will have time to rest from their tremendous tasks; many will get the opportunity, hitherto sought in vain, of watching wild creatures and
making discoveries about them. It is for these men and women, and not
for the privileged few to whom ornithology has been an indulgence, that
I have written this little book.
I shall be very pleased if anybody who reads it becomes interested in

Oundle, November 1940


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Preface to 1974 edition

A great many people over three decades have been introduced by
Watching Birds to the tremendous fields of interest that opened out
before them once their attention has been drawn to the possibilities.
Beyond the pure, largely aesthetic, pleasure of just looking at birds are
to be found the delights of watching birds and attempting to understand
more of their lives, their movements or their biology. As an interest,
birdwatching is compulsive: amongst its charms are that as a hobby it
can be practised anytime and anywhere, and that the commonest of
birds retain their charm and fascination no matter what level of expertise is reached.
This much was realised by James Fisher when he first devised this
book. He could hardly have visualised the impact that it would have: the
fantastic growth of birdwatching and bird conservation societies is in
large part due to his influence, and for many years the mainstream of
fieldworkers involved in the studies ofthe British Trust for Ornithology
was initially stimulated by his abilities to present general ideas in an attractive manner.
The structure he planned remains quite adequate, though the attendant techniques may have progressed farther than even James Fisher
could visualise. Where my own ideas differ from his, I have tried to state
in an open discussion our points of view, and in many cases I have
retained outdated figures because of the interesting comparisons they
offer between the 1930's and the 1970's.
It is a daunting task to revise the bird book on which you cut your
teeth: it is the surest measure of the man who wrote it that what is
needed, after thirty-odd years, is an updating and not a sweeping
Tring, January 1974


Note on the illustrations

Some illustrations in the book are based on those in the original edition,
although for the most part the original illustrations have been revised
and redrawn, but James Fisher's thanks to the various workers responsible for the basic data must be reiterated. For some of the distribution
maps John Parslow's book, Breeding Birds ofBritain and Ireland, has
been an invaluable source of information in bringing details up to date.
It would have gratified James Fisher greatly to see how many of the
new figures in this edition are based on the results of the cooperative
fieldwork of members of the British Trust for Ornithology published in
Bird Study, B.T.D. News and other journals. The value of such
products of combined enthusiasm is perhaps best seen in the B.T.O. interimAtlas maps, the maps of ringing recoveries and in the bird population Indexes. To all the fieldworkers involved, and to the B.T.O., I
express my gratitude.
Crispin Fisher has put his artistic talents, with excellent effect, to the
bird drawings in this edition, and by common consent we have retained
some line drawings from the original edition so that father and son may
appear together. The majority of the photographs, including that on the
cover, are my own but my thanks are due to Richard T. Mills for so ably
remedying the deficiencies in two widely separated fields.

1 Introducing the birdwatcher

to the bird
"My remarks are, I trust, true in the whole, though I do not pretend to
say that they are perfectly void of mistake, or that a more nice observer
might not make many additions, since subjects of this kind are

9 December 1773


Though they are by no means the most ubiquitous, numerous,

curious, or diversified forms of life, it is nevertheless a fact that birds
have had more attention paid to them than any other corresponding
group of animals. Many attempts have been made to discover why so
many people like birds, but nobody has so far given a really satisfactory
answer. When it comes, it will probably be found partly from a sort of
mass observation and partly from the long and detailed history which
birdwatching has enjoyed, particularly in Britain. Certainly birds are
relatively obvious and always about us, but they are extremely mobile in
contrast with other beautiful and interesting natural things like flowers.
All sorts of different people seem to watch birds: James Fisher knew
of a Prime Minister, a Secretary of State, a charwoman, two policemen,
two kings, one ex-king, five Communists, four Labour, one Liberal, and
three Conservative Members of Parliament, the chairman of a County
Council, several farm-labourers, a rich man who earns two or three
times their weekly wage in every hour of the day, at least forty-six
schoolmasters, and an engine-driver. To these can be added today (in
reflection of both political and cultural shifts of emphasis) two Princes
Consort, at least two Presidents, numerous peers, a Field Marshal and
many people falling under the general heading of 'show business personalities'. The number of birdwatchers is now impossible to estimate-our only guide to its enormity is the membership of the various
formal clubs and societies, some local, some national, which must now
be approaching the half-million mark. Obviously, these are only a small
fraction of those with a genuine interest in, and feeling for, birds.


Watching Birds

The reasons which make these men and women interested in birds
are, surely, very divergent. Some, when asked, can give no particular
reason for their liking for birds. Others are quite definite-they like their
shape, their colours, their songs, the places where they live; their view is
the aesthetic one. Many of these paint birds or write prose or poetry
about them. Still others, like several of the schoolmasters, are grimly
scientific about them, and will talk for hours on the territory theory, the
classification of the swallows, or changes in the bird population of
British woodland during historic times. The luckiest ones are those who
blend the two: retaining the aesthetic pleasure and adding to it the
delights realised by an inquisitive interest.
nature of the observer. Those who read this book may give bird
watching anyone of these definitions; which is a sound reason why we
should get down as soon as possible to the business of introducing the
bird-watchers to the birds.

Birds are animals which branched off from reptiles at roughly the
same time in evolutionary history as did the mammals. Though both
birds and mammals have warm blood, from anatomical considerations
it is clear that these two branches are quite separate, and that the birds
of to-day are more closely related to reptiles than they are to mammals.
The parts of the world that birds live in are rather limited. Though birds
have been seen in practically every area of the world from Pole to Pole
and at heights more than that of Mount Everest, yet they have rarely
been found to penetrate more than about 30 feet into the earth or about
150 feet below the surface of the sea; and every year some part of their
lives has to be spent in contact with land, for birds cannot build nests at
sea, even though some freshwater species build floating nests and rarely
step onto dry land.
In the hundred and thirty million years or so in which birds have
existed as a separate class of animals, they have retained their basic
structure to a remarkable extent, and, compared with the situation in
other classes of animals, even the apparently most widely distinct birds
are internally little different. To avoid going into anatomical details, it
must be enough to say that the same bones (that is, homologous ones)

Introducing the Birdwatcher to the Bird


exist in the wings of humming-birds and ostriches, and in the feet of

hawks and ducks. What has happened in the course of evolution is that
these have been modified for different purposes. The wing of the
humming-bird has become perhaps the most efficient organ of flight in
the animal kingdom; (the humming-bird is, as far as we know, one of the

I Birds' feet adapted to differing modes of life: (a) finch family (passerine
birds}-perching; (b) woodpecker-tree climbing; (c) Sparrowhawk-seizing
prey in flight; (d) Water Rail-load-spreading; (e) Puffin--(three-toed) swimming; (f) Coot--(Iobed) swimmirig and load-spreading; (g) Shag--(four-toed)
swimming; (h) Barn Owl-gripping prey

16 Watching Birds
few birds which can actually fly backwards); while that of the ostrich,
which can no longer fly, is used as an organ of balance and of display.
The talons ofthe hawk, provided as they are with terrible claws, grasp
its prey, and are usually the weapons which cause the victim's death
(rather than the beak); while the feet of the duck are webbed so that it
can walk upon mud and swim. Figure 1 gives just some idea of the immense variety of foot adaptation and Figure 2 shows some of the adaptations of beaks to feeding.
Many are the ways in which birds are adapted to their surroundings,

2 Birds' beaks adapted to special feeding methods: (a) Hawfinch, Crossbill,

Goldfinch and Bullfinch-seed crushing and extraction; (b) Avocet-skimming for small molluscs, crustacea, etc; (c) Everglade Kite--(snail eating) shell
piercing and extraction; (d) flamingo-filtering plankton, etc; (e) Galapagos
Woodpecker Finch-tool holding (stick to "winkle" insects from holes)

Introducing the Birdwatcher to the Bird


and to the lives which nature (or, if you like, evolutionary history) has
taught them to live. Many interesting adaptations can be seen in British
birds: so that they may climb trees and cling to them while hunting insects, the woodpeckers have feet with two toes pointing forwards and
two aft, and the under-side of their tail feathers is rough where these rest
against the trunk of the tree as the birds climb; their beaks are like
chisels, for often they carve much of their nest out of the living wood,
and their food habits take the great beaks under bark and into crevices
in their search for insects. The central tail feathers of woodpeckers are
specially strengthened to serve as a prop while the bird feeds, but those
of the Nuthatch, a bird of very similar habits, are not. The Nuthatch,
however, unlike the woodpeckers, can climb both head-up and headdown because it is not dependant on support from its tail. In North
America one group of woodpeckers has gone even farther, not so much
in adaptation as in the habits produced by such an adaptation. They
have deserted insect catching for sucking the sap of the trees-hence
their name of sap-suckers-and this is a warning to the unwary: birds
are not always what they seem, and adaptations may hide relationships,
or indicate false ones.
Many birds are beautifully adapted to their surroundings at the
earliest stage of their lives: the egg. The eggs of the Ringed Plover and of
other shore birds often resemble very closely the pebbles among which
they are laid (Plate 14); those of birds which build open nests are often
coloured with a protective pattern of pigment. But it is a biological
economy to lay an egg without pigment where pigment is unnecessary.
The eggs of woodpeckers and owls are white when they are laid, and
coloured later on only by dirt, and these birds nest in holes where their
eggs cannot be seen by enemies. Oddly enough, the egg of the Puffin still
has grey or red spots, like faint copies of those of its cousin, the
Guillemot, which rather suggests that the Puffin has only recently (in
the evolutionary sense) taken to nesting in burrows. One of the nicest
adaptations of all is shown by the Guillemot, an auk which nests on very
narrow cliff ledges. The egg of the Guillemot is conical-almost pearshaped-and if knocked, rolls in a tight circle on its narrow end, thus
staying on the ledge when an egg of normal shape would surely have
rolled off.
When we speak of adaptation of the sort which we have just
described, we must remember that our attention is likely to be drawn to
the more remarkable examples of adaptation to special needs and away


Watching Birds

from the fact that practically every organ and part of an animal is
adapted (directly or indirectly, efficiently or inefficiently, in greater or
lesser degree) to the animal's surroundings, or to its demand at some
period of its total or daily life. A bird is what it is partly because of the
immediate environment-since food or weather may affect its colour or
size-partIy because of heredity-which provides machinery,
producing in turn variations on which natural selection can act-partly
because of chance-since chance appearance of such new variations as
are ignored by natural selection may determine some of the characters
of an individual or even of an isolated group of individuals. We must
remember that not only special kinds of beaks but beaks in general are
adaptations. A wing is an adaptation for flying. An egg is an adaptation
for nourishing the young. Adaptations, in birds as in other animals,
must be regarded in terms of the perspective of the ages, the dynamics
of evolution, and the complicated mechanism of heredity. We may
regard any characteristic as adaptive if it can be explained as fitting the
bird to its mode of life.

The skeleton of a bird (Fig. 3) is, in general plan, the same as that of
other vertebrate animals. Essentially, it consists of a strong box made
up of many bony elements, with a variety of attachments. The head,
first, is attached to a column of strong articulating vertebrae, the
backbone. To the axis provided by the head and vertebrae are attached
various appendages; to the head the jaws; to the lower vertebrae of the
neck from one to four "floating" ribs; to the vertebrae of the back, ribs
which curve forwards to join the huge breast-bone, forming the strong
case inside which the lungs and heart lie, and to the outside of which is
attached, towards the back, the shoulder girdle; to the remaining
vertebrae the hip girdle. The shoulder girdle supports the elements of the
wings, the hip girdle those of the legs.
The number of vertebrae in birds is most variable, unlike that in
mammals. A swan may have twenty-five bones in its neck, a sparrow
only sixteen. (It is odd to recollect that a giraffe, in common with man,
has only seven.) In the region of the back some pigeons may have only
three vertebrae whose ribs meet the breast-bone, while ducks, swans,
gulls, rails or allks may have seven or eight. In the last group the thorax
(the box formed by ribs and breast-bone) is very long, and the un-

Introducing the Birdwatcher to the Bird



Here main flight-feathers

neck of
- ____ J
Outer lower arm-bone

F"-:::t:=~f:TL_U pper arm -bone

Shoulder-girdle ---1'Ir.3'-'very strong

Keel of breastbone

Three front toes


Bird skeleton with wings raised-common names given

protected abdominal region between it and the base of the tail is very
short-a useful adaptation towards a swimming or deep-diving life.
One of the chief characteristics of a bird's bones that we should
expect to find is that of lightness, an adaptation towards flying. Though
birds may have large bones, these have not a massive structure. Most
are hollow-some have huge cavities which may contain extensions of
the air-sacs of the lung-and only occasionally do we find cross-struts
(as in the albatrosses). These bones owe their strength and rigidity to a
structure so sophisticated as to be emulated by engineers in modern


Watching Birds

girder design. They are almost unbelievably lighter than a mammal

bone of the same size.
Though there are many characteristics of a bird's skull which show
its evolutionary affinities rather than the tasks to which it is adapted, yet
it is better for us, in thls short review, to consider it from an adaptive
point of view. There are several requirements which a bird's skull must
fulfil. First, it must be light; secondly, the loss ofteeth and manipulating
fore-limbs during the course of evolution must be compensated; thirdly,
the brain and eyes must be accommodated and protected. The first
point is covered by the fact that few skull-bones of birds are more than
plates and struts; the second by the high development of the horny beak,
which has to act almost as a limb, and is, in practice, a very effective
one; the third by the huge orbits, which leave only a very thin partition
between the eyes on each side. These restrict the rest of the brain to the
back of the skull-which is accordingly broad. That part of the brain
which deals with smell (of which birds have very little sense) is much
reduced; that which deals with co-ordination of movement and balance
is understandably large; that which deals with what are sometimes
called the "higher functions" (such as logic, or aesthetic appreciation, in
humans) is small. Nonetheless, some of these "birdbrains" (so wrongly
called) are capable of navigating in most weathers, with really pinpoint
accuracy, to a wintering place in Africa, and in the case ofthe Swallow,
back here to the very same barn or garage to nest in the succeeding
The greatest differences between the skeletons of birds and those of
other vertebrates are found in the skull and in the pectoral girdle and
forelimb. The latter corresponds to the shoulder-blade, collar-bone,
arm, forearm, and hand of man. The pectoral girdle is attached to the
bones of the main trunk at only one point, where the front end of the
shoulder-blade is attached, on each side, firmly to the fore-part of the
breast-bone. The two shoulder-blades are braced together across the
front by the collar-bones, which are fused in the middle to form what we
call the wish-bone. Behind, the free ends of the shoulder-blades are
bound by stiff and strong ligaments to the ribs and to the vertebrae of
the back.

When the wing is working the strain comes directly on to the box
formed by vertebrae, ribs, and breast-bone which are together called the
thorax. This box has therefore to be extremely strong. It is. At the back
the vertebrae are fused together, at the sides the ribs (often with

Introducing the Birdwatcher to the Bird



1Ht-lr- 0 uler


Upper arm-bone


4 Skeletal wing from below

strengthening bony processes) are bound to each other by further
ligaments, and in front the breast-bone is built on engineering principles
that combine strength with great lightness plus a keel for the attachment
of the powerful muscles of the wing.
This is the basis upon which the wing can operate. The part that flaps
(Fig. 4) is composed of three units. Attached to the shoulder-blade by a
ball-and-socket joint is the upper arm-bone (humerus), a single strong
rod. To the other end of the humerus are joined the two bones (radius
and ulna) of the forearm, and to them in turn is joined the third unit,
several small bones, largely fused together (carpals and metacarpals),
representing the mammalian wrist and hand.
The muscular force which works the wing is derived almost entirely
from huge wedges of muscle attached from the wish-bone in front to the
base of the breast-bone below and the shoulder-blade behind. The fibres
of these great muscles converge to an insertion on the humerus. By far
the larger part of these pectoral flight muscles is concerned with the
downbeat of the wing: inside these, connected to the humerus by a complex but subtle tendon system, are the smaller muscles that lift the wing
for the next flap. Next time you carve the breast of a chicken, or better a
pheasant, look out for these two muscle groups.
It is the humerus, then, which takes the strain of the wing beat,
though the feathers of the wing (Fig. 5) are carried not on this but on the
other bones of the arm. The secondary feathers are attached to the ulna,


Watching Birds




5 Wing feathers from above

the lower and thicker of the two bones of the forearm; these feathers
play the major part in propulsion. The primary feathers are attached to
an elongated wrist, and to two bones which correspond to the index
finger; these play an effective part in steering. Thumb and third finger
are present in rudimentary form, the former bearing a bunch offeathers
often called the bastard wing, which appear to have the aeronautical
function of a wing slot. The other fingers are absent.
All other attempts at flight by vertebrates (and there have been upwards of half a dozen) have involved the development of flaps of skin,
stretched, as in the pterodactyl, from the little finger to the feet, or, as in
the bat, over all the outstretched fingers to the feet (Fig. 6). In no case
except birds have feet been kept out of the mechanism; besides which,
skin is clumsy to fold compared with feathers. So it can be seen that
birds have a considerable advantage over other flying vertebrates. The
extent of this advantage can be gauged from the fact that pterodactyls
are extinct and bats restricted in range and habits, whereas birds are
Because birds have been able to keep their feet out of their flying
mechanism, these organs have been left free for the play of evolutionary
adaptation. But because birds can fly, there are some considerable
problems to be got over before they can run. The great pectoral muscles
that work the wings may weigh, in the pigeon, over a quarter of the
weight of the whole body. The centre of gravity ofa flying bird lies well
in front of the joint between leg and body. Hence, if the bird is to stand

Introducing the Birdwatcher to the Bird



6 Three types of wing. Only the bird's wing is independent of legs and tail.
Note that the pterodactyl uses one finger only for the wing frame, but the bat
employs four, with the thumb for clinging


Watching Birds

upright, the girdle of the hip must clasp the vertebrae in a vice-like grip.
This, of course, is what it does. In front of and behind the socket into
which the head of the thigh-bone inserts, the central part of the hipgirdle is elongated and fused with the vertebrae. It will be remembered
that the vertebrae of the back were fused together the length of the
thorax, to give a strong base for the working of the wing. The last one or
two of these rib-bearing vertebrae are also integrated with the hip girdle,
and are clasped by the broad iliac bone. Below them, perhaps ten or
eleven more vertebrae are fused with the girdle, and beyond these two or
three more little ones may project; these are the last ofthe caudal or tail
vertebrae, and represel:t what there is of a true tail in modern birds. So
the total result is that the bird has a very rigid back from the base of its
neck to its tail, a back whose rigidity is achieved by the fusion of
vertebrae to each other, or to the hip girdle, forming one of the main
elements of this strong, box-like structure which not only protects the
vital organs but also withstands the stresses and strains of both flight
and walking.
What appears to be the thigh of a bird is in reality its shin, and what
looks like its knee the wrong way round is its ankle. The true thigh-bone
(femur) is usually short, and runs almost horizontally forwards to the
knee, which may lie closely applied to the surface of the body just about
under the centre of gravity, tucked well away into the body feathers and
out of sight.
Running downwards and slightly backwards, the true shin (apparent
thigh) is a single long bone (tibio-fibula); all that is left of the second legbone found in most land vertebrates is a sliver applied to the surface of
the main bone. The next member runs downwards and forwards, a
single bone (tarso-metatarsus) derived from elements originally part of
the ankle and the upper ends of three of the toes. The toes themselves
are never more than four in number; the first (big toe) is nearly always
turned backwards when it is present. The fifth (little toe) is entirely
It can be seen that the bird's leg, composed as it is of three single rigid
bones, jointed together, provided with toes at the end, is ideal for its purpose, and can be adapted for running, standing, taking landing strain,
and catching prey. The knee- and ankle-joints of the bird lie some distance from the hip-joint and toe-joints, and work in opposite directions.
Thus they constitute perhaps one of the most effective shock-absorbing
mechanisms in the animal world.

Introducing the Birdwatcher to the Bird



Anybody who has prepared a fowl for the table will know, and those
who have carved one will suspect, that the "guts" of a bird (Fig. 7) are
contained in a cavity stretching from rib box to hip girdle, and covered
very largely by the downward projection of the breast-bone. This cavity
is generally known as the abdominal cavity, and in it the long continuous tube of the alimentary tract is coiled. Food is taken in by the
beak, laced with saliva from glands in the mouth, and squeezed down
the throat by muscles at the back of the mouth. In the throat region the
tract is called the gullet or oesophagus. It may be expansible and used to
store food, or it may have a large special bag attached to it for storage; if
present, the latter is known as the crop. Crops may sometimes be used
as "udders"; those of pigeons secrete a milk-like protein-rich fluid used
to feed the young. Sometimes they may be used as extra gizzards: that
of the Hoatzin has muscular walls which can squeeze the juices out of
its food.
The gullet continues through the thorax, passing behind the heart, to

Upper arm-bone
Main vein of body

Blood vessels
of neck

7 The internal organs (pigeon)


Watching Birds

reach the abdominal cavity, where it immediately broadens out into a

large bag, the stomach. Usually, the first part of this has walls supplied
with glands which secrete acid in order to continue the processes of
digestion started by the saliva, and the after-part is lined with muscle
and developed as the gizzard. Many birds which live on grain or on hard
vegetables have large gizzards and frequently swallow small stones,
which are retained in the gizzard as an aid to crushing. Others which
live on flesh have no gizzards at all, but have glands over the whole of
the stomach; and in some birds of prey, for example, the gizzard serves
as a collecting area for bones and fur which are later "cast" up as
After the stomach, the tract continues as a loop known as the
duodenum. Into this run three ducts from the pancreas, and down the
ducts run secretions which change starch to sugar and break down
proteins and fats to simpler forms. Ducts also run into the duodenum
from the liver, which may be even larger than the stomach, which it
often surrounds. The top surface of the liver is closely applied to the
diaphragm, the broad muscular wall which divides the cavity of the
thorax (containing the heart and lungs) from that of the abdomen. The
liver serves as storage for excess sugars, to secrete bile to aid digestion,
and as a general "cleaning up" organ where toxic materials are removed
from the blood.
After the duodenum we reach the small intestine proper. This is often
very long, especially in vegetable-feeding birds. In it digestion continues, and the main part of the absorption of the digested products
takes place. It loops and coils about the abdominal cavity, each loop
being held in place by a membrane attached to the back wall, and practically fills the cavity. Finally, it joins the rectum, a wide short tube
which leads to the cloaca. At the junction of the small intestine with the
rectum we find one or two blind tubes (caeca) branching sideways.
Sometimes these are quite large, and it is possible that matter such as
cellulose is broken down in them by bacterial action and rendered fit for
absorption. It is thought, too, that water and proteins may also be
The final passage, the short cloaca, communicates with the exterior,
but before this it receives the excretory ducts from the kidneys and the
reproductive ducts from the testes or ovaries. Thus the cloaca is a
general-purpose opening; it is both excretory and reproductive, and is
the only such opening in the lower part of the bird's body.

Introducing the Birdwatcher to the Bird



Though the heart of birds is built in a different way from that of mammals (it has more affinities with the reptile heart), it is four-chambered,
and apparently is just as efficient, since in it oxygenated blood is effectively separated from the de-oxygenated blood which has delivered up its
oxygen to the body. Birds have a more rapid heart-beat than mammals,
and their temperature is considerably higher-from about 37C. in
birds like the emu and ostrich to about 44C. in some small larks and
finches. Like mammals, the temperature of their body is more or less
constant and independent of the temperature of their surroundings,
rising and falling only slightly with periods of activity or rest. As in
mammals (e.g. bats), so there are, in some birds, some exceptions to this
rule. Under certain conditions of the environment, such as the cold
nights of the hIgh Andes, the maintenance of body temperature by small
birds like humming-birds (which have a relatively large surface in
proportion to their weight) becomes difficult or impossible. Some
humming-birds, under these circumstances, become torpid. At first
their breathing becomes violent, and they lose the power of flight. When
touched, they make a peculiar whistling sound. When completely torpid
they are quite rigid, the head is pointing upwards and the eyes are
closed, the breathing appears to stop. It may take the birds about half an
hour to recover from this stage. Recently, the quite astonishing discovery was made in America that the Poor Will (a nightjar-like bird)
can hibernate for long periods in rock crevices to survive the winter.
Under these conditions of torpidity, the body temperature drops to
about SOC. and the general rate of bodily processes falls to about three
per cent of normal.
Thus under certain exceptional circumstances birds can revert to the
reptile-like condition of having a body temperature that is not constant.
In adult birds this condition is very rare, is only found in certain species,
and, when present, is an adaptation to special circumstances of the environment. On the other hand, the young (in the nest) of most birds
show a variable body temperature. This is because the mechanism of
temperature control does not get into full working order until most of
the feathers have grown sufficiently to produce an efficient insulating
layer stopping a continual heat loss. Hence the care which many birds
take, by brooding and, equally important, by shading from the sun, in
order to protect their young from excessive cold or heat.


Watching Birds

The rapid heart-beat of the bird is a necessary adaptation, not only

towards keeping up its temperature, but towards supplying the huge
demands of the flying muscles. These require sugars, and oxygen to
"burn" them with, for the large amounts of energy needed. And the blood
has to carry the necessary supplies from the liver-the sugar
storehouse-and the lungs. The heart itself is large, and takes up more
space in the thorax than does the heart of a mammal; its walls are very
thick and muscular, for it has a lot of work to do in pumping the blood
round the body-blood which carries, besides sugar and oxygen, the
waste gas carbon dioxide (the product of the "burning" ofthe sugars),
other waste products, proteins for body building, fats for storage and
more energy, the secretions of the ductless glands (chemical compounds
often called hormones which act as "messengers"), and various bodies
concerned with the destruction and neutralisation of bacteria and

A bird's windpipe opens at the back of the tongue and runs down the
throat to the top of the thorax. Here it broadens out into the voice-box
or syrinx. This consists of a main chamber, with a bony band inside.
This band has two processes attached to it on which a membrane is
stretched; there may be other membranes present as well, and together
these act as vocal cords, producing sound and song. Not surprisingly,
the whole structure in noted songsters is much more complex than the
simple quacking mechanism of the ducks. The nearly voiceless Ostrich
has no real syrinx at all, nor have the vultures. From the bottom of the
voice-box two tubes branch off, one to each lung. These tubes feed not
only the lungs but, through them, nine "air sacs" which are often large.
These sacs increase the amount of air available inside the bird for
use-very useful if the species is a great songster or a great diver. By
means of a complex routing of the air (not yet properly understood)
these air sacs also fill the lungs directly after an out-breathing, so that air
is available for respiration in the periods before it can be breathed in
from outside, giving birds the ability to extract oxygen whilst breathing
out and in-an exceedingly efficient technique and one that maintains
the vital energy needs of the flight muscles. And since birds cannot
sweat, a lot of the water exchange which helps to keep their temperature
under control takes place over the inner surface of these sacs.

Introducing the Birdwatcher to the Bird



Placed within the abdominal cavity, closely applied to the back wall
on each side of the mid-line, lie a pair offlattish, lobed organs. These are
the kidneys, and from the middle of each a slender tube runs direct to
the cloaca. The kidneys filter waste products from the blood and excrete
them in semi-liquid solution through the ducts.
Most female animals have a pair of ovaries slung from the abdominal
wall close to each kidney, but most birds have (for some reason) only
the left ovary; if the right is present, it is nearly always a vestige. The
ovary looks like a bunch of grapes; its size varies greatly, from enlarged
with forming eggs in the breeding season, to near-invisible in winter. A
long, thick, coiled tube which runs to the cloaca on the left side has at its
upper end a great funnel which opens directly into the abdominal cavity
near the ovary. This is the oviduct (Fig. 8).
When the breeding season arrives, a chain of events is set in motion
inside the bird, usually by changes in temperature and daylength. Certain ductless glands begin to pour their secretions, often under the influence of the pituitary-a special ductless gland in the region of the
brain-which appears to act in some ways as a master gland. Changes



The reproductive organs of female and male birds


Watching Birds

begin to take place in the ovary (which is a ductless gland in its own
right, producing hormones like the others), and the unfertilised and immature eggs begin to take in yolk and get bigger.
In the male bird organs are attached to the back wall of the abdominal cavity near the top of the kidneys in much the same place as the
ovary in the female. In the male, however, they are paired and of equal
size and function. These are the male reproductive organs; oval bodies,
tiny in the off-season but huge at breeding time. They consist of a part
known as the testis, in which the sperms and some hormones are
produced, and another part mainly concerned with storage of the male
fluid. From each organ runs a narrow duct, of about the same size as the
tube from the kidney, to the cloaca.
When birds copulate, the female generally takes up a crouching position and lifts her tail. The male mounts on her back and applies his
cloaca to hers. By muscular action, a dose of male seminal fluid is then
pumped into the female's cloaca from the sperm-ducts, where it has
been stored. Some male birds which might otherwise have difficulty in
securing efficient transfer of the sperm (such as ducks, which often
copulate on or under the water), have a special muscular penis attached
to their cloaca which fits into that of the female. Not many birds,
however, are provided with such an organ.

The sperms of the male birds, of which there are many thousands in a
dose of fluid, are living things with an independent existence, and have
many of the properties of separate organisms. One of these properties,
that of swimming against a current, now comes into play; and the
sperms make their way, against the slow movement of the secretions
from the walls of the oviduct, up this tube. They may meet an egg or
eggs either at the top of the oviduct or in the oviduct itself; when they do,
they fuse with the egg. As soon as a sperm has entered an egg, the egg's
surface changes chemically and no other sperms can get in. The egg,
once fertilised, rapidly begins to divide. It already has a supply of yolk
and consists of a dividing, developing group of cells above, and a mass

of nutritious yolk below.

The next step is for the yolk with the developing embryo upon it to be
wrapped in a safe and useful parcel. This is done by cells in the walls of
the top of the oviduct, and the first wrapping consists of an albuminous

Introducing the Birdwatcher to the Bird


substance which, in the final full-sized egg, can be seen as a sort of curly
part ofthe white between the yolk and the ends ofthe egg. When the egg
is laid and the shell is hard, this curly part acts as a kind of spring shockabsorber suspending the yolk, hammock -like, safely in the middle of the
albumen, or "white". As the egg passes farther down the oviduct, more
of the white of egg is secreted and deposited round it. Still farther down
the tube are cells which secrete the chalky shell, and farther on still are
more cells whose job it is to produce pigments to make the typical
pattern on the egg. The egg is finally laid, broad end foremost, by contractions of muscles in the wall of the cloaca.
The embryos of animals more simple than the hen-those of frogs,
for instance-develop by division of the fertilised egg and rapidly form
a little round mass which then becomes something like a yolk-filled cup.
The embryos of birds (Fig. 9) cannot develop in this way because of the
great size of the yolk. So instead of growing as a roughly ball-shaped
mass, they start life as a plate of cells draped over the top of the yolk. To
begin with, this plate is streak-shaped, and very soon after the egg has
been laid the first cells of the nervous system can be seen in the mid-line.
After forty hours in the chicken, the new animal is over a quarter of an
inch long, is more sausage-shaped than streak-shaped, and is beginning
to separate a little from the yolk. This separation is most pronounced in
the front third of the growing body. This part is going to be the head,
and already swellings can be seen where the eyes are to be; down the
rest of the body little round dots indicate the segments of the growing
bird. Four days from laying we can distinguish brain, eye, ear, and
heart, the last as a sort of bag surprisingly near the head. Plates of muscle are already arranging themselves in the segments of the body. After
a week the eyes have become really large and the limbs have begun to
appear. All the same, it would be difficult to tell whether an embryo was
that of a chicken, a crocodile or a cat.
By now the chick is getting big and its growth demands a supply of
oxygen. This has to be carried in blood-vessels, and large ones develop
in the membranes which surround the chick. During the next day or two
little cones appear all over the surface of the embryo; these are the buds
of developing feathers. By the tenth day we can tell that we have a
young bird, because the limbs are of the proper bird shape and structure, and we can see the beginnings of a beak. At the end of a fortnight
quite a lot of real bone has been laid down in the skeleton in place of soft
cartilage, and the muscles are well developed. The beak has been


Watching Birds

ind}parts of brain


of body

Special membrane
through which chick
breathes & into
which it excretes

Umbilical stalk
connecting chick
to breathing-

Membrane containing
salt water which
bathes surface of


Air chamber


9 Three stages in the development of the chick: (a) 36 hours after the egg is
laid (back view); (b) five days after laying (side view), limbs beginning to
appear, breathing membrane developed and eyes well advanced; (c) nine days
after laying, embryo well developed
provided with an egg tooth with which the chicken can break its way out
when the moment of hatching comes about a week later; the feathers
have begun rapid growth and are much longer, and the head is less huge
in proportion to the rest of the body.
The period of time between laying and hatching is known as the incubation period. It may be as long as forty or fifty days in certain
seabirds, ostriches and brush-turkeys. In the hen it is three weeks, in
some small perching birds only ten or eleven days.

Introducing the Birdwatcher to the Bird


When the time for hatching comes, the chick pushes its beak into the
air chamber at the broad end of the egg and takes a first fill of air into its
lungs. Up to now its oxygen supply had come from the air diffusing
through the walls of the shell and. received by the network of bloodvessels, outside the chick itself. Having filled its lungs with air, the chick
then strikes the egg shell and breaks it. After an hour or two it may have
broken off the broad end of the egg and may have struggled into the outside world. Helping it to chip away the shell is the small, hard
protuberance on the end of the beak, the "egg tooth", which can still be
seen in many young birds for two or three days after hatching.
In general there are two kinds of young birds. Nidifugous (literally,
"fleeing the nest") chicks can run as soon as they are hatched and hatch
at a comparatively advanced stage. Game birds, wading birds, and
ducks have nidifugous chicks, all very active and capable of running,
swimming, and hiding. Their eyes are open and functional, and often
they can at least partly feed themselves. The most striking example of a
nidifugous bird is the young of the brush-turkey, a Megapode from
Australia and nearby countries. The egg of this bird is incubated, not by
either parent, but by the heat of fermentation of a pile of decaying
vegetable matter scratched up by the male bird. The young often have
to find their own way out of a pile of stuff, and as soon as they have
managed to do this, they can flutter off the ground on wings which have
reached a remarkably high stage of development. On the other hand,
birds which nest in holes or which build complicated and comfortable
structures can afford to have their young hatched at an earlier period of
development; these are, then, nidicolous. A newly hatched tit or
blackbird has scarcely any developed feathers at all and is naked, ugly
(almost reptilian), to all intents and purposes quite blind, and helpless.
It would be wrong to end this introduction to birds without brief
reference to their feathers, which are, after all, one of their most distinctive features. No other animal possesses feathers. In its early embryological stages, the feather closely resembles the reptilian scale from
which it has evolved. There are a variety of feather types: most birds
have their body insulated by an "underclothing" layer of filamentous
down, covered by the contour feathers that we see, which themselves
have fluffy, insulating bases. The wing and tail feathers have much the
same basic structure as the contour feathers, but are specially strongly
Feathers are made of the protein keratin, and are secreted by special


Watching Birds

Pheasant Vane feather

with Aftershaft


10 Various types of feathers and a detail of a vane feather to show the

hooked barbules which interlock the feather barbs

cells in the skin. Figure 10 shows how extraordinarily complex their

structure is when looked at closely, and how important preening must
be to the bird, for the mechanical properties of the feathers (and thus
weatherproofing and flight) depend on the interlocking of the tiny hooks
on the barbules. Naturally structures of this sort are subject to wear and
tear, and most small birds change all their feathers, in a process called
moult, at least once and sometimes twice each year.

2 Arranging the birds

"Faunists, as you observe, are too apt to acquiesce in bare descriptions,
home in a man's study, but the investigation of the life and conversation
be obtained but by the active and inquisitive, and by those that reside
much in the country."

1 August 1771


There are about eight thousand five hundred species of birds in the
world, according to the authorities. This is really quite a small number;
there are over a hundred thousand kinds of molluscs and about three
quarters of a million kinds of insects (of which a third are beetles), and
entomologists are still describing thousands of new species of insects
every year. Yet there are probably more ornithologists than there are
malacologists or entomologists in the world.
It is likely that birdwatchers are able to satisfy their keenness so well
mainly because of the interest taken in birds by taxonomic zoologists.
Taxonomic zoologists usually inhabit museums and spend most of their
lives examining, arranging and sorting skins and skulls. These
painstaking people have one of the most difficult tasks in the whole of
zoology, for in their arrangement of their animals in a natural classification they have to bear in mind many very different principles. When a
collection of bird skins turns up from some part of the world that has
not been very well worked, the taxonomist has to be an historian, an
evolutionist, a geographer, an anatomist, a bibliographer, and often a
mathematician before he can be justified in assigning his specimens to
their proper species or if necessary to a new species. Even then, ifhe has
all these qualities, he may often have to rely on an intuitive flair for
In the Linnaean system (a system of classification published by Linnaeus in 1758) every animal bears two names, a generic one and a
specific one. The same generic name is not permitted by the international rules of nomenclature to occur twice in the animal kingdom,



Watching Birds

though specific names may often be repeated. Once a name has been
given to an animal by an authority, with a description in a recognised
scientific journal or some other such printed paper, it sticks unless
somebody can later prove that a name has already been given to the
animal concerned or that the animal does not merit being classed as a
new species. This rule usually works well and saves a great many mistakes and inconveniences. Sometimes, however, it has awkward results.
For instance, the names of the British Song Thrush have been changed
several times in the last twenty years because of new discoveries about
the dates of publication of the original papers in which it was described.
The Manx Shearwater is called Puffinus pUffinus and the Puffin Fratercula arctica. This seems curious to British birdwatchers, but has to be,
since the name Puffinus was originally given to the shearwater.
It should be realised that most modern taxonomists have two main
points of view when deciding what a species is. They have to look at
their animal, perhaps first from the point of view of practical convenience, giving each animal a label, or "pigeonhole", so that it may be
easily and accurately referred to again; and secondly they have to look
at it from the evolutionary aspect. What they like to have as a species is
a collection of animals which their colleagues would readily agree to be
such, and which, when met with alive in the field, would have some reality to the animal watcher. It is often extraordinarily hard to decide
whether a population of animals, including birds, really is all of one
kind, either because of the natural variability in biological material, or
because of a phenomenon called convergent evolution (when quite
different species may develop similar features to suit life in a special
A simple definition of a "species" is: two animals belong to the same
species if they inhabit the same area, have the same tradition of structure, colour, voice, and habits, and tend to breed with each other rather
than with similar animals which do not have those traditions.
Two animals do not necessarily belong to the same species if they interbreed in the wild. There are many examples of distinct species which
have increased their range in the course of evolution so as to overlap. In
the region of overlap they may interbreed, producing a mixed or hybrid
population. Nevertheless, this does not mean that they are of the same
Two animals belong to different species if, when inhabiting the same
area and having much the same outward form, they avoid interbreeding

Arranging the Birds


by devices of colour, voice, or display, or by selecting different habitats

in that area. As we will see in a later chapter, Chiffchaffs and Willow
Warblers are very similar and are quite hard to distinguish even in the
hand. In nature they remain distinct species because of their distinctive
songs (by which they recognise each other) and probably by slight
differences in their choice of habitat.
A great range of size, colour, and geographical distribution does not
destroy the reality of a species. Thus, if you compared a Puffin from
Spitsbergen with one from southern Europe, you might easily conclude
that they were of different species until you had seen a collection of birds
intermediate in size from the intervening coast of the north Atlantic. As
a matter of fact there is a beautiful gradation in size, increasing from
south to north. Taxonomists have given names to the populations in
various regions up the coast, and these populations can all be arranged
in order of size and latitude. Not one of these populations could be
called a different species, but they can be quite suitably called different
subspecies or geographical races. It would be possible to go even farther
and say merely that there was a gradation of "cline" in size from south
to north.
Sometimes a population of animals of one species may originally
have been spread over a large area. In the course of time and for various
reasons (perhaps an ice age) this population may have been broken up
into isolated groups. As time goes on, such groups, breeding among
themselves, may begin to show differences from other groups, which
become more and more marked as time incl -:ases. Such is the birth of a
subspecies. As soon as the average difference between one group and
the next becomes consistently and obviously greater than the average
difference between one individual and another within a group, we are
justified in calling each of these groups a subspecies. When these
differences become really great, sufficiently so for interbreeding to
become impossible for one reason or another, we are forced to go
farther and call the groups different species.
Many examples of such separation are found on islands, and in Britain there are quite a lot of island forms of birds. Thus there is a
mainland Wren, a Shetland Wren, a Hebridean Wren, and a St Kilda
Wren (Fig. I I). When the St Kilda Wren was first described, it was
given the rank of a full species, but zoologists have now decided that it
should only be called a subspecies. Perhaps in a thousand years or so it
may become even more different from the mainland form and may be


Watching Birds









_A.rCtic .


Iceland Wren

/ .... - .... Faeroe Wren






from the Inner Hebrides
tend to be rather
variable and generally
intermediate between
mainland and (outer)
Hebridean forms



Wrens from Fair Isle

are intermediate
between mainland &
Shetland forms

Wren--distribution of various forms in Britain, the Faroes and Iceland

worth calling a species again. The borderline between species and subspecies is (in the case of island forms) extremely difficult to draw. The St
Kilda Wren, for example, has wings about 10% longer than its
mainland counterpart, is considerably heavier, and very grey, only the
tail being the rich rufous brown of the mainland bird. The song, too, is
held by some to be different, but this is difficult to judge because the
towering St Kilda cliffs make a very different sounding board to an
English woodland!
Some subspecies of birds are not purely geographical ones since there
are other barriers which can isolate populations of birds. In America
one ornithologist who happened to be a very keen field worker discovered that two races of Clapper Rails overlapped in broad
geographical range. He was unable to explain why they had distinctive

Arranging the Birds


characteristics of form until he found that one race lives on marshes and
the other in dry country. Here, then, is an example of two races
separated ecologically, that is, by their natural ways of life.
It is probably not worthwhile for the ordinary amateur field ornithologist, or birdwatcher, to trouble very much about the definition of
the species he is working with. In Britain, at all events, the work has
already been done very intensively, and although there is still a bit of a
battle going on between those who like to recognise similarities between
races of birds ("Iumpers") and those who like to recognise differences
("splitters"), this need not concern us very much. As far as British birds
are concerned, the amateur can rest assured that the list of species is in
the hands of a very capable committee of the British Ornithologists'
Union. The committee meets regularly to discuss very carefully all the
additions and subtractions necessary for the British list, and all the
changes of name that bibliographical and anatomical research have
made necessary. If the reader wants to know the exact names of the
species on the British list he should consult the B.O.U. book The status
of birds in Britain and Ireland (Oxford, 1971). The additions and corrections are published annually in the Ibis, which is the journal of the
British Ornithologists' Union, and if the birdwatcher uses these lists and
with their aid examines his experience in the field, he will get a better
idea of the reality of species and subspecies than any series of random,
theoretical definitions could give him. It is important nevertheless for
him to realise that improvements in our knowledge of classification can
come from his own work. Birds are notoriously hard to c1a~sify properly, and for help in their task zoologists are having to depend on every
new source of ideas that they can touch. Today, the systematist has to
consider not merely things like measurements, structure, and colour,
but also voice, habits, geographical position, migration, population,
type of nest, egg size and shape, and now even the shemical structure of
the egg-white proteins. In many of these asp"ects, the amateur
birdwatcher can help greatly.

No two animals are alike. It is impossible to say that two animals are
truly the same from the zoological point of view, except in the rare case
of identical twins (and this is not really a safe case). We have already
traced some general trends of mass variation, such as the trend in the
Puffin towards bigness as it gets north; and there are many more


Watching Birds

examples. Thus, birds from moist regions tend to be darker than those
from dry regions, and in cold parts of the world exposed parts like feet
and beaks tend to be reduced in size and often covered with feathers.
But this kind of organised and correlated variation is very different from
individual variation. Sometimes certain individuals of a species are very
different from the norm; for instance, they may lack pigment altogether,
in which case they are called albinos, or they may have an excess of, or
altogether lack, some but not all of the normal pigments. These variants
are called mutants and are rare things, and the more extreme kinds
probably play very little part in the evolution of a species, although in
some moths black ('melanistic') mutants playa novel role in the modern

60 0 N

Up to


Up to

12 Guillemot-distribution of the bridled form as a percentage of total

breeding stock around the British Isles

Arranging the Birds


world in camouflaging the individual more successfully on grimy, sooty

tree trunks.
Sometimes, however, variants appear very regularly, so that there is
an apparent (and often a real) balance of numbers between variant and
norm. Such a variant is present in our Guillemot, for certain individuals
have a white "bridle" or "spectacle" circling and running backwards
from the eye. Among the breeding stocks of Guillemots in Britain, the
bridled birds (Fig. 12) increase from under a quarter per cent of the total
population in the south of England, up to 26 per cent in Shetland.
Beyond this northern point of Britain the percentage increases still
further until it reaches 53 per cent in the south oflceland and probably
more on Bear Island. Clearly there is a definite gradation in space ofthe
proportion between bridled and normal Guillemots. This gradation, or
cline, is not perfectly continuous from north to south; there are a few inconsistencies round the coasts of Britain, and bridled birds are less common in the north than in the south of Iceland. All the same, it is broadly
true to say that the number of bridled Guillemots increases as one goes
The Fulmar is a bird in which there are several colour phases; it may
show every gradation from almost white on head and underparts to
deep, smokey grey all over, in which plumage they are called "blue".
The farther one goes from Britain towards the east coast of Greenland,
the darker become the Fulmars. Again, this colour-phase-cline is not a
simple south to north affair; it is possible that the birds actually get
lighter northwards up the west coast of Greenland, and the situation in
the European arctic seas of Spitsbergen is obscure. A lot of information
about the distribution of the colour phases of the Fulmar has been
collected from ships at sea, and late in 1939 the Admiralty were kind
enough to issue a Fleet Order asking officers to collect information on
this subject and send it to the British Trust for Ornithology, resulting in
the distribution map in Figure 13.
We must also remember that in birds (as, for example, in man) there
is variation in size between individuals. Sometimes this is associated
with the sex of the individual. In most birds, the males are larger and
longer-winged than the females (the birds of prey are an exception to
this) but, over an above this, while most individuals of a species are
reasonably close to the mean, exceptions do occur, in rapidly
diminishing numbers as the deviation from the mean becomes more
extreme. Figure 14 shows how this occurs in the Water Rail.


Watching Birds

13 Fu1mar-distribution of "dark" phase Fulmars in the North Atlantic in

summer as a percentage of total breeding stock

Further up the taxonomic scale, above species and subspecies, stand

genera, containing a number of related species. Related genera are
gathered into Families and related families are gathered into Orders.
Let us give an example. The British Twite is recognised as a
geographical race, resident in the British Isles. It has been named Carduelis jlavirostris pipilans (Latham). Latham was the authority who in
1787 gave the name pipilans to this particular bird. According to the
International Rules of Nomenclature, his name has to be put in brackets
because he originally attached the name pipilans to a different genus
(Fringilla), from which the bird has now been removed.
The British Twite belongs to the subspecies pipilans of the species
jlavirostris (to which belongs also the subspecies Carduelis jlavirostris
jlavirostris, the Continental Twite, and others) of the genus Carduelis
(to which belongs also the species Carduelis cannabina, the Linnet, and

Arranging the Birds


others) of the Family Fringillidae (to which belong also the genera Coccothraustes (Hawfinch), Pyrrhula (Bullfinch), and others) of the Order
Passeriformes, or perching birds (to which belong also the families Corvidae (crows), Sturnidae (starlings) and others).
From the ordinary fieldworker's point of view the important thing is
the bird. He is more likely to be interested in the species than in the
genus. The one thing essential to him is the power to identify correctly.
From whatever point of view he may approach bird watching, he needs
skill in identification. This skill is as vital to him if he has the aesthetic
approach as if he has a scientific one. If he cannot identify he will find it








14 Wing and bill lengths of Water Rail, male and female, in the field and as
museum specimens


Watching Birds

difficult to enjoy himself with birds. If he begins to watch birds straight

off with the help of one of the more old-fashioned text-books, he may
soon be in trouble, because he will be asked to look at birds from the
standpoint of the museum taxonomist, and the museum man has his
own special way of describing birds. He can describe every feather but
not every pose, and can describe the structure of the voice-box but say
nothing about the voice. The reader may be given detailed descriptions
of all that is permanent in a skin, but less good descriptions of things like
the colour of the eye and legs, and poorish descriptions of any voice or
However, with today's wide choice the problem is one of making a
selection from the tremendous field of identification guides available.
There have been great strides in recent years in presenting bird illustrations and descriptions compactly, drawing attention to vital identification features. It is worth remembering that these giant strides
forward have largely been based on the fieldwork of amateur
enthusiasts, who have faced the problems of putting a name to the bird
in the field, analysed them, and gone a long way to solving the other
problem of transferring some of their knowledge and skills to others.
Let us trace roughly the course of the average birdwatcher as he discovers the delights and defeats of identification.
1. He becomes interested in birds, perhaps because of the influence
of somebody else.
2. He cannot make them out, especially when he is alone.
3. So he gets a book with pictures, which may be of two types, (a)
rather accurate pictures, or (b) pictures designed not as pictures but as
aids to identification, particularly in regard to colour. ,
4. Armed with these he improves his knowledge of birds.
5. He begins to get acquainted, not merely with the birds, but also
with their habits.
6. With the further weapon of habits he begins to realise the nuances
of identification and can speculate about them.
7. Realising this, he probably widens his circle of ornithological
8. He then becomes capable of identifying birds, not merely by the
text-book colours, but also by flight, song, and all sorts of minor habits
of the most subtle kind, called by most birdwatchers "jizz".
9. He is then in a position to contribute to our knowledge of bird

Arranging the Birds


Upper tail



The topography of a bird

Such is the evolution of the birdwatcher's attitude towards identification. It is not by any means our purpose, in a short, introductory book
such as this, to try to give a key to the British birds, when there are so
many books serving this purpose already on the market. What must be
said, however, is that you will not get anywhere watching birds without
practice, and that you should try to strike a balance between field observations of your own and the notes you take, and the use of text-books.
If you are puzzled by a new bird you see, it is not always the best plan
to rush straight off to the text-book. You may have one in your pocket,
and the best thing to do is to write accurate notes on every characteristic
you can, for comparison with the text-book description later. Watch the
new bird for as long as possible, note the sort of places it likes, what food
it is seeking, its call note or song (though this is difficult, often, to
transcribe), its type of flight, and of course its colour, shape, and so on.
Try to estimate its size in comparison with any other birds that are
about. Any colours or adornments which are clearly of use to the bird
for signalling purposes, like white marks on the wings, white rumps or
red breasts, are probably equally useful to you in identification. It is
very useful to have a fair knowledge of the technical terms for the
various parts of the bird and the various tracts and rows of feathers.
Figure 15 names the parts in general use, and though some of the names
may seem to be a little cumbersome, they are really worth remembering.

3 The tools of birdwatching

"In the last week of the last month five of those most rare birds, too uncommon to have obtained an English name, but known to naturalists by
the terms of himanotopus or [oripes, and charadrius himanoptus, were
shot upon the verge of Frensham-pond, a large lake belonging to the
bishop of Winchester, and lying between Wolmer-forest and the town of
Farnham in the county of Surrey. The pond keeper says there were three
brace in the flock; but that, after he had satisfied his curiosity, he suffered
the sixth to remain unmolested."


There are a number of general tools that can be considered as essentials

to the birdwatcher-binoculars, a notebook, and some guides to bird
identification, for example. There are others, like suitable clothing, a
camera, a small library of bird books, which while not vital can considerably increase his comfort, skill and overall enjoyment of the hobby.
Beyond this, the more involved he becomes in some fields of bird study,
the more sophisticated and specialist is the equipment needed: rings and
traps for marking, a tape recorder for bird song, 25" to the mile maps
for census work and so on. Lying beyond even this are cars and inflatable boats at one end of the scale and nestboxes and dummy eggs in
a variety of colours at the other.

This seems the sensible place to start, because any form of

birdwatching can only be improved by the choice and use of suitable
binoculars which will bring the action nearer or allow detailed study of
colour and plumage. However, it should never be forgotten that in some
circumstances-geese against an estuary sky or a "smoke column" of
waders shimmering over the mud-binoculars can restrict the view and
detract from the overall beauty of the scene. But, in general, with
binoculars you not only stand a reasonable chance of recognising your
bird, but you can see, and wonder at, what it is doing. We are immensely
fortunate that modern technology has made available, at reasonable


The Tools o/Birdwatching


price, a wide (perhaps bewilderingly so) choice of binoculars. What

points should you bear in mind when making your choice? There are
some reasonably simple rules:





QUALITY: generally speaking, you get what you pay for-your

dealer should advise you on this. Remember that an expensive buy
may last a lifetime, but you do not have the opportunity to change
your mind (unless you are very rich!) or to obtain two pairs of
glasses for different situations.
MAGNIFICATION: most birdwatchers find x6 too low-x 7 x8 x9
are good general-purpose magnifications. For watching large
reservoirs, estuaries or the sea, x 10 or x 12 will be more satisfactory, but may well be too heavy to be held steady by a feminine
hand. Variable magnification ("zoom") binoculars are usually
heavy and often suffer from poorer definition.
FIELD OF VIEw: should be as large as possible, and tends to be
better with lower magnifications. A wide-field is most helpful in
woodland or similar situations. Tryout rival brands in the field.
LIGHT GATHERING: most binoculars have both magnification and
object glass (the larger lens) diameter marked on the body-e.g.
8 x 30, 10 x 50. A quick and simple way of estimating the light
gathering capabilities of binoculars (that is, how good they are
likely to be in the poor light of early morning or evening) is to
divide the object glass diameter by the magnification. So for
8 x 30, this becomes 3.75 and for 10 x 50 it is 5.0. The higher the
figure, the better. To obtain similar evening performance to the
10 x 50, 8 x 40 would be needed.
OPTICAL PERFORMANCE: this must always be checked in the field
before finally purchasing. Check that you can hold and focus the
glasses easily; that there is no distortion of vertical lines (look at a
pole or pylon); that there are no colour fringes ("rainbow" halos
round the image). Some slight lack offocus round the edges of the
field is normally acceptable, but the central area (where you will
usually concentrate) must be crystal-sharp.

Now, what are the right binoculars for you? If you are birding mostly in
woodland or heathland areas, a lower magnification, wide-field and
good light gathering will be needed. For the wide-open spaces like an estuary, then x lOis more likely to be your choice. If a compromise is essential then perhaps x 9 fits the bill, but do consider the possibilities of











[J B

16 Plans for nestboxes, from the Bra Field Guide No.3, Neslboxes-(a)
hole nesters, small (tits, Nuthatch, Pied Flycatcher, etc); (b) open-fronted,
small (Robin, Spotted Flycatcher, Pied Wagtail, etc); (c) large tray (Barn Owl,
Kestrel, feral pigeon, etc); (d) Barn Owl box-with the supply of natural nest
sites for the Barn Owl declining you can help conserve the species with appropriately placed nestboxes of this type


Watching Birds

becoming the proud owner of two pairs of binoculars, each suited to

your precise needs.
For even higher-powered work, like the close examin.ation of
"difficult" waders or the identification of distant ducks, a telescope can
be used-although this instrument takes a little getting used to! The
light transmission is poor, allowing the use of a telescope only in fairly
good light conditions. The field of view is tiny, and spotting your bird
takes practice. Nonetheless, modern telescopes represent a considerable advance on those featured so often in birdwatching cartoons.
Focusing is now by a twist-grip, rather than by pulling and pushing on
brass draw-tubes, and a similar twist-grip allows the magnification to be
changed (usually over a range x20-x60 or similar) without loss of
focus. So you find your bird on lowest power, and then "zoom" up to
get the best available view.


A camera is by no means the necessity that binoculars are, but it is

often useful and can be, on occasions, a highly rewarding accessory.
Photographs--especially colour transparencies--of places you have
visited and birds you have seen not only provide a valuable record, but
also untold enjoyment when viewed again, sometimes years later. Here
too, modern technology has brought really sophisticated equipment
within the reach of most of us, and it is by no means necessary for the
beginner to limit himself solely to habitat shots. The price and availability of equipment lead me to suggest that although a larger format gives
higher quality, there is no real alternative to a 35 mm single-lens-reflex
(SLR) camera. With these, the picture you see in your viewfinder is the
one that appears on the film, so that you can be sure that your subject is
both correctly positioned and in focus. Many SLR cameras now have
the exposure metering system incorporated in the viewfinder, which
helps considerably with wildlife photography. Most SLR's have easily
interchangeable lenses (the Pentax/Praktica screw is perhaps the commonest) so that you can quickly attach a long-focus (telephoto) lens for
bird close-ups if you so desire. A word of warning though-a 200 mm
lens may suffice if you are working from a hide on largish birds, but for
"stalking" even garden birds without a hide, at least a 300 mm lens is

The Tools ofBirdwatching



This is another area where personal comfort and preferences hold

considerable sway, and where sometimes a compromise must be struck.
Despite this, there are some essentials and some limits that may be
If you are birdwatching in remote, or exposed areas, especially if (as
in Britain) the weather may suddenly deteriorate, and if you are going to
do any hill-walking or rock scrambling, then you must be properly
equipped. In these circumstances a twisted ankle could be as serious as
two broken legs, so take no risks. Always have adequate warm,
weatherproof clothing and some food and drink. Always have properly
robust and properly soled footwear for the job. Always carry at least
one brightly coloured item of clothing, and in really remote areas, a
Otherwise, the basic rule is to be warm (or cool) enough, and
reasonably weatherproof. Totally waterproof clothing or footwear
usually results in excessive condensation, so you finish up wet anyway!
Other than in the circumstances I have already outlined, the
birdwatcher should always be inconspicuous (and this applies to his
behaviour as well as his clothes). Large numbers of more or less waterproof, insulated anoraks are available for winter wear, and thick
trousers keep your legs warm. Nylon over-trousers keep out cold winds
as well as rain. A good compromise for the spring and autumn (long
periods often embracing summer also in Britain), and one that I favour
myself for its quick-change opportunities and easy portability, is a combination of thick roll-neck sweaters and a nylon "kagoul" (a sort of
hooded smock). This allows you to keep your body temperature where
you want it, and to be totally wind or waterproof when necessary, all
without carrying a huge rucksack for your wardrobe.
If at all possible, avoid clothing that rustles or crackles as you move,
or which scrapes noisily past twigs and leaves. Much of the art of getting close views of birds lies in effective stalking; quietness, steady and
unhurried movements, judgement oflight and wind, and a steadily builtup knowledge of the meanings of the other noises of the countryside and
the likely behaviour of the bird that you wish to see, all play their part.
It is astonishing just how much many people miss as they walk
through the countryside. Chattering noisily, scuffling through leaves
and snapping twigs, walking across the middle of open ground or along

52 Watching Birds
the top of a bank-all are bound to give the birds the maximum warning
of your arrival, and to restrict your views to distant ones. Always try
and use the available cover to mask your progress-keep behind
hedges or on the fringe of clearings, keep below the top of the river bank
or sea-wall, pausing cautiously from time to time to peer over the
top-it is worth it for the better view. If you can, keep the sun behind
you or over your shoulder, as colours change or vanish if you must look
into the sun. The birdwatcher has fewer worries about the wind direction than the student of mammals, because birds have generally little or
no sense of smell, but gazing into a stiff breeze can be very eyewatering
and irritating.
Rich may be the rewards of caution, quiet and stillness in woodland.
Remain part-concealed for several minutes, and if no motion betrays
your presence you may be accepted as just another part of the
landscape, with birds resuming their normal lives around you. In this
way, parties of birds like tits, Wrens, Treecreepers and Goldcrests may
approach to within a few feet.

We have already discussed the use of a camera to record particular

bird habitats as an "extra" to your birdwatching, but a notebook to
record details of numbers, plumage or behaviour is an essential. For
over a century amateur birdwatchers have played a large part in the
study of bird populations and their movements in Britain-and in essence this work is based on the facts and figures accumulated from
scores of notebooks such as yours. This is the place to record your first
Chiffchaff of the spring, or the last Swift or House Martin of autumn; to
note the numbers of the various birds you see, especially in areas that
you visit regularly. Also this is the place for the beginner to note details
of new birds-how they strike him, how he feels that his bird-book let
him down-so that he may identify this species with greater ease the
next time he meets it. The same applies to the more experienced
birdwatcher meeting a less-common species for the first time, and in
either case, if the words can be accompanied by sketches, very much the
better. Birders have coined the word "jizz" for that indefinable
something that makes a bird recognisable--usually it is something to
do with the way it stands, feeds or flies, rather than with its
colouration-and this is often easier expressed in a sketch than in

The Tools of Birdwatching


words. For a real rarity, such notes, taken in the field with the bird
before you, are quite vital in deciding or confirming its identity.
Perhaps the best sort of notebook is the pocket-sized, loose-leaf
variety, with a stiff waterproof cover. At the end of each year, the notes
can be removed and filed (looking back on them later is immense
fun-and often helpfully interesting), and a fresh series of pages inserted. The real record keepers, those with the tidy minds, find benefit in
transferring all their records and notes for each species to a series of
filing cards for quick reference. This is a habit that it is well to regard as
a discipline, but (unlike many disciplines) it has obvious merit and interest, for from such records are county and regional bird reports compiled. Daily notes and sketches are perhaps best and most interestingly
kept in diary form, but systematic records are best filed in a regular
order. We saw earlier that taxonomists delight in changing the order in
which the various species are listed-some being more avant garde
than others. Regrettably, this only confuses the poor birdwatchers (as
those who have tried to find their way about a new Field Guide and the
old Handbook will well know). Recently the editors of a number of
county bird reports got together to agree an order, and until this is
replaced, it can sensibly be taken as the most practical. It is published
(cheaply) by the B.T.O. as Field Guide No 13 under the title A species
list of British and Irish Birds, and contains not only the accepted
English names, but also the correct scientific ones. It is worth having a

There is an incredible number of bird books-mostly useful, mostly

interesting, some vital, some fascinating. They range from field guides
to help you identify our birds in their various plumages, through encycIopaedaic multi-volume sets, with details not only of plumage, but of
anatomy, biology, behaviour and distribution, to monographs on a
single species, regional bird books and travelogues.
It is, of course, impossible to list them all. What may be both possible,
and sensible, is to indicate a few of the more important books for all
birdwatchers and a selection of more general-interest topics. From this,
the more dedicated bibliophile, or the budding ornithological librarian,
will have found a starting point. The nature of a birdwatcher's library is
essentially personal; both authors of this book, for example, have been


Watching Birds

involved with seabirds-for James Fisher books on seabirds formed

only a section of his vast and comprehensive library, whereas for myself
they dominate my small collection, indeed to the point of a nearly complete set of the works concerning St Kilda, a seabird Mecca.
New books are appearing at a tremendous rate, and it would be a
brave man who set out to emulate the world-famous photographer Eric
Hosking, who must now have one of the most complete modern private
ornithological libraries. Thus many of the works mentioned by James
Fisher in earlier editions of this book have been superseded-some, as
we will see, have not, and remain in the "must" category. I have divided
the list into books of various types, with here and there some notes. As
with any other piece of equipment, only you can judge the book which is
best suited to your working interest or taste. Most, if not all, of these
books should be readily available in a public library, so have a look at
them before plunging.
FIELD GUIDES TO IDENTIFICATION. Any birdwatcher is bound to need
one or more of the comprehensive field guides in the course of time.
Many more-elementary paperbacks on (for example) garden birds are
available but are not listed.
The Birds of Britain and Europe with North Africa and the Middle
East; Heinzel, Fitter and Parslow; Collins.
A Field Guide to the Birds ofBritain and Europe; Peterson, Mountford
and Hollom; Collins.
The Hamlyn Guide to the Birds of Britain and Europe; Bruun and
Singer; Hamlyn.

These are the really comprehensive works, with great

and fascinating detail on all aspects of the birds included. The Witherby
Handbook is the oldest, but remains the most comprehensive. Bannerman has a wealth of information, much of it personal or anecdotal. In
preparation in several volumes is a new work, Birds of the Western
Palaearctic, but this series is unlikely to be completed for several years
yet. The two "Popular" volumes are cheaper condensations of the main
The Birds of the British Isles; Bannerman; 12 vols; Oliver and Boyd.
The Handbook of British Birds; Witherby, Jourdain, Ticehurst and
Tucker; 5 vols; Witherby.
The Popular Handbook of British Birds; P. A. D. Hollom; Witherby.

The Tools ofBirdwatching


The Popular Handbook of Rarer British Birds; P. A. D. Hollom;

Some of these (for example James
Fisher's Shell Bird Book, David Lack's Enjoying Ornithology and
Michael Lister's Birdwatcher's Reference Book) are excellent sources
of further titles.
Breeding Birds of Britain and Ireland; J. Parslow; Poyser.
Atlas of European Birds; K. H. Voous; Nelson.
Bird; L. and L. Darling; Methuen.
A Bird and its Bush; M. Lister; Phoenix House.
Bird Navigation; G. V. T. Matthews; second edition (also in paperback), Cambridge University Press.
Birds and Woods; W. B. Yapp; Oxford University Press.
Birds of the World; O. Austin and A. Singer; Hamlyn.
The Birdwatcher's Reference Book; M. Lister; Phoenix House.
Erifoying Ornithology; D. Lack; Methuen.
An Eyefor a Bird; E. Hosking; Hutchinson.
The Life of Birds; J. C. Welty; Constable.
Man and Birds; R. K. Murton; Collins, New Naturalist Series.
The Migration of Birds; J. Dorst; Heinemann.
Pesticides and Pollution; K. Mellanby; Collins, New Naturalist Series.
Population Studies of Birds; D. Lack; Oxford University Press.
Seabirds; J. Fisher and R. M. Lockley; Collins, New Naturalist Series.
The Shell Bird Book; J. Fisher; Ebury Press and Michael Joseph.
Where to Watch Birds; J. Gooders; Andre Deutsch.
Where to Watch Birds in Europe; J. Gooders; Andre Deutsch.
The World of Birds; J. Fisher and R. T. Peterson; Macdonald.
Bird Ringing; C. J. Mead; B.T.O. Field Guide.


Helping with techniques or equipment.

Discovering Bird Watching; J. J. M. Flegg; Shire.

Binoculars, Cameras and Telescopes; J. J. M. Flegg, B.T.O. Field

The Bird Table Book; T. Soper; David and Charles.

Nestboxes; J. J. M. Flegg and D. E. Glue; B.T.O. Field Guide.
A Field Guide to Birds' Nests; B. Campbell, J. Ferguson-Lees;


This is a very brief selection from the dozens


Watching Birds

available-many published under the auspices of Collins New

Naturalist series.
The Greenshank; D. Nethersole-Thompson; Collins, New Naturalist
Monograph 5.
The Hawfinch; G. Mountfort; Collins, New Naturalist Monograph 15.
The Herring Gull's World; N. Tinbergen; Collins, New Naturalist
Monograph 9.
The House Sparrow; J. D. Summers-Smith; Collins, New Naturalist
Monograph 19.
The Kingfisher; R. Eastman; Collins.
The Life of the Robin; D. Lack; Witherby.
The Mystery of the Flamingoes; L. Brown; Country Life.
Penguins; J. Sparks and T. Soper; David and Charles.
The Puffin; R. M. Lockley; Dent.
A Study of Blackbirds; D. W. Snow; Allen and Unwin.
Swifts in a Tower; D. Lack; Methuen.
The Woodpigeon; R. K. Murton; Collins, New Naturalist Monograph

The Wren; E. A. Armstrong; Collins, New Naturalist Monograph 3.

One of the areas in which experience can be of the greatest value to a

birdwatcher (excepting those unfortunates who are completely tonedeaO is in the recognition of birds by their calls or song. It really helps
very greatly to be able to "spot" your bird in this way. Likewise one of
the areas of greatest problem for the writer of a field guide is in
"translating" a call, or, more difficult still, a song, into written
English. Usually what results is ajumble of consonants looking like the
name of a rural Polish railway station, and only rarely can the poor
birdwatcher be significantly enlightened ("chiff-chaff" and "cuck-oo"
for instance). There are other ways oflearning, though, especially now
that records, and record players are widely available. Here is a list of
some record series that are available.
Listen the Birds; produced by the RSPB and the Dutch Society for Bird
Protection; recordings by Hans A. Traber and John Kirby; a series
(now fourteen in number) of 7-inch 33t r.p.m. discs, each with
several related species, or with species common to one type of
habitat; EPHT 11-14, and HDV 7-14.

The Tools ofBirdwatching


Bird Recognition; an aural index recorded by V. C. W. Lewis on HMV;

presented as three volumes, each with three 7-inch 45 r.p.m. discs
and an explanatory booklet, again divided (with 15 or 16 species per
volume) on a habitat basis; 7 EG 8923-31. Victor C. Lewis has also
produced other 12-inch 33tr.p.m. records for HMV;A Tapestry of
British Bird Song, CLP 1723, sixty-o~d species; Guess the Birds,
XLP 50011, 24 species arranged as a test of skill as well as for entertainment; and, for Marble Arch, Bird Sounds in Close-up, two 12inch records, MAL 1102 and 1316, both with a wide spectrum of
about forty species arranged in habitat groupings.
Shell Nature Records; published by Discourses for Shell-Mex and B.P.
Ltd; recorded by Lawrence Shove; this series is based on a habitat
classification-marsh and riverside, moor and heath, woodland,
etc.-with seven 7-inch 33tr.p.m. records so far; DCL 701-7.
BBC Records; the Wildlife Series contains bird recordings, again
divided on a habitat basis; RED 96 has Welsh birds, RED 103 a
large number of woodland birds, summer and winter, RED 109 garden and water birds, etc. 12-inch 33tr.p.m.
It is well worth "getting into practice" for the forthcoming season by,
for example, spending the occasional March evening listening to recordings of the summer migrants that will soon be arriving. Likewise, you
may search your "woodland" records in the hope of identifying the call
of some unseen bird (though most of these untraceable calls turn out to
have been made by the very versatile Great Tit!). Many difficult, or
distantly-seen species like waders, become much easier to identify once
you are familiar with their calls.
One step beyond this, and regarded by more and more birdwatchers
as another tool of their trade, lies the portable tape recorder. Recording
equipment-parabolic reflectors and all the other paraphernalia-is
outside the scope of this book, but it is worth bearing in mind that a tape
recorder can be used not only to record bird-song spectaculars, such as
the Nightingale or dawn chorus, but also to draw birds towards you.
Many birds (but some have shown themselves aloof to temptation so
far) will come to investigate the source of a "broadcast" of a recording
of their call or song~ften, like the Nightingale, coming right out into
the open to pour forth a reply. Here is yet another technique-novel,
and ripe for much more development-for getting those close views
that enhance your birdwatching so much.

4 Migration

"We must not, I think, deny migration in general: because migration certainly does subsist in certain places, as my brother in Andalusia has fully
informed me. Of the motions of these birds he has ocular

12 February 1772

In practically every group of animals, wherever these animals live, there

can be found members which indulge in orderly mass movements.
These movements may happen every few hours, every day, every few
days, every month, every year, or every few years. Animals do not, as
far as we know, have regular movements of the order of every week,
because the week is a human invention which bears no relation to
natural phenomena like the daily turning of the earth, the transit of the
moon, or the movement of the earth round the sun.
The lives of most birds are based on an annual rhythm; although in
some large birds, particularly tropical seabirds, this may not hold true.
This annual rhythm may produce several sorts of migration. It may
consist of wholly local movements, or dispersals in no particular direction.1t may consist of the typical more or less south to north movement
that makes it possible for us to label such a large proportion of the birds
on the British list as summer or winter visitors. This south to north
movement may even involve crossing the Equator. In the tropics,
however, there may be orderly seasonal movements, but these may not
be concerned at all with latitude. The birds move every year at the best
time to avoid the dry season, and these movements every year may be
quite irregular in their nature and yet orderly because they always
happen at the same season. When we discuss the special case of
rhythms extending not over one but over several years, we find
ourselves dealing with the remarkable cases of periodic irruptions,
movements of birds when their population is high into geographical
areas not usually associated within their natural range.




Many kinds of birds are described as residents or sedentary, because

they are never known to move very far from where they are hatched.
Yet every year these birds move about locally and sometimes this movement is more or less orderly. Some birds move up and down mountains.
Some form flocks in winter and leave their breeding territories to roam
together about the hedges and fields of the countryside in search of
food. The Yellowhammer and Chaffinch are typical British birds which
never appear to migrate in the true sense, but which flock up and roam
about open country. Similarly tits and Goldcrests, highly resident birds
in Britain, flock up in autumn and go on foraging parties for the winter.
Of course, the picture is somewhat clouded in Britain and Ireland in
winter by the large numbers of some species (like the Chaffinch and
Goldcrest) which arrive here as migrants driven out of the Continent by
the severe winter.
There seems to be scope for a fair amount of individual variation,
since some individuals of normally resident species may carry out true
migrations. For instance, the Starlings that breed in Britain are almost
certainly resident and do not move more than locally, whereas those in
the neighbouring part of the Continent truly migrate, in a more or less
east to west direction, so that they may arrive in Britain in the winter.
Local movements start rather earlier than most people imagine, since
even before the parent birds have finished with their last brood, the
offspring of the first broods may have been driven away and may have
scattered through the country. These young birds often join with the
flocks and quite often roost in company. The early autumn movements
seem quite highly organised and deserve a good deal more study than
they have had so far.

The movements of many birds are governed by the necessity for

breeding in the summer season, rather than any particular need to move
southwards in winter. Yet the movements of these birds are too large
and too definite to be called local movements. This especially applies to
sea-birds, which may disperse for many hundreds and sometimes even
thousands of miles from their breeding haunts. For example, the two
young Puffins marked on St Kilda, the most westerly of the Scottish
islands, which had crossed the Atlantic to be recovered in New-


Watching Birds

foundland. They must have done this as much by swimming as by

flying. The distance was over 2,000 miles.
Sea-birds have the whole of the ocean to feed in, but only a limited
number of sites to nest on. Dispersal is therefore very wide, and
Gannets, which only breed in a handful of colonies in Britain spread out
allover the Continental shelf, where the water is not too deep;in the
winter. The direction of their spread may be north, west, east, or south;
where the bird goes seems to depend largely on its individual inclinations. This is not quite true of young Gannets, which seem, during
the three years before they can breed, to indulge in true north and south
migration, reaching the coast of North-west Africa.
Kittiwakes, Fulmars and other petrels, and most of the auk tribe are
oceanic birds in winter. Their spread from their breeding haunts may indeed lead them south in the Arctic regions, where ice occupies the open
sea; but where there is no ice their movements seem to be in the direction of adequate food supplies, or in no particular direction at all.
Besides ice, one of the factors limiting where they can go is probably
heat tolerance. Thus the Fulmar goes as far south, summer or winter, as
the 60F isotherm; which means that it goes farther south in summer
than in winter. This does not mean, however, that the Fulmar is an ordinary north to south migrant. Its movements are far more accurately
described as dispersals.

It is becoming clear that a far larger number of birds than was at first
supposed undergo more or less regular changes in population. When a
peak of population is reached, it very often means that the pressure of
numbers causes a big movement which it seems reasonable enough to
call a migration. Some authorities describe these as irregular migrations
or irruptions. Perhaps the latter term is better, since one of the
characteristics of these mass movements is that the interval between
them is often much the same, between nine and twelve years, and almost
always between five and sixteen.
In Britain irruptions of the Crossbill arrive at quite short intervals
(every three to ten years), and in some years these have been so large
that a remnant has actually stayed on to breed here. The permanent colony of Crossbills in Norfolk was established after one of these
irruptions. Pallas's Sand-grouse used to appear in Britain in large



numbers about every twelve years, but has not done so now for fifty or
sixty years. Rose-coloured Starlings seem to have a cycle of nine years
or so, and at the peak of this often irrupt from Asia to Europe and breed
for a year or two. In these peak years birds quite often reach Britain.


Although perhaps not strictly falling under the general heading of

migration, this is a good place to mention the fantastic expansion of
range that the Collared Dove has undergone in recent years. When
James Fisher wrote the earlier editions of this book, he made no mention of the Collared Dove, which was then considered, if at all, as a
rather drab relative of our Turtle Dove, resident in Turkey and other
areas in the eastern Mediterranean. In the years following the Second
World War, this previously rather static species became suddenly
dynamic, and started to spread rapidly westward across Europe. In
1955 and 1956, the first two or three pairs reached eastern England to
breed (shrouded in secrecy and excitement). As I write (in 1973), the
Collared Dove breeds in all, or almost all, British and Irish counties, and
on many of the western Irish and Scottish islands. Even on remote St
Kilda, where there is little cover for it to breed, it is a regular visitor
(perhaps even a non-breeding resident) and two years ago its irrepressible westward push resulted in breeding pairs in Iceland! There must
now be tens of thousands of breeding pairs in the British Isles-from
only one pair less than twenty years ago. Indeed in some parts of
eastern England (and even around grain silos in western Ireland) many
people consider Collared Dove numbers and feeding habits sufficiently
in conflict with man to call them "pests".


Watching Birds

Most of our summer visitors and nearly all our winter visitors in Britain are typical migrants, that is, they are birds which have two distinct
ranges, though in many cases these ranges may overlap. Between these
ranges they have an orderly movement in spring and autumn. When
they are making this movement we say they are on passage.
What, then, are the reasons for these regular seasonal migrations?
Primarily, we must suppose, creatures endowed with the power of flight
have the opportunity to exploit areas which, while rich in food in the
summer months, are impossibly cold in winter. Obviously there are
degrees in this. Thus some species (like our summer visitors) move only

17 Isotherm map showing mean January temperatures (F}--note cold centre in eastern Siberia



from overwintering areas in the tropics to our temperate climates, and

may fit in two or three broods of young during their visit, while others
(like many ducks, geese and waders) overwinter in temperate regions
like western Europe before hastening northwards to take advantage of
the very short Arctic summer. They must arrive on the tundra as the
snow and ice retreats, for summer is short. However the "crop" of insects waiting to be harvested is enormous in a favourable year, and
rearing a single brood may not be difficult if the timing is right. The
Sanderling-a wader a little smaller than a Song Thrush-has evolved
a neat additional technique for these circumstances. On arrival in the
Arctic, the pair build two nests, and the female lays a clutch of eggs in
each. She then sits on one clutch while the male incubates the
other-thus raising two broods in the time normally taken for one.
A glance at the map of the mean January isotherm shows clearly that
much of the Palaearctic region (comprising Europe and Asia) is completely inhospitable in winter. Clearly, too, ifbirds retreat from the cold
following the temperature gradient, many will move west as well as
south (the Himalayas provide another incentive for doing this) to the
coasts of Europe warmed by the Gulf Stream, which extends a finger
well to the north of Scotland. Hence the offshore islands of Britain and
Ireland are a winter refuge for huge numbers of a wide variety of
species (Fig. 17).
It is often said that Britain is well situated for students of bird migration, but in fact there may be so much movement, of so many types, that
the picture becomes rather clouded. There is a stream of migrants in
autumn from Greenland and Iceland-some passing on (Greenland
Wheatears), others staying (Barnacle Goose). Another stream leaves
the Arctic via Scandinavia, again with some species staying with us
(Knot and Dunlin) and others (Arctic Tern) moving on. The Arctic
Tern probably spends more time in daylight than any other living
creature, for it breeds in the perpetual days of the Arctic summer,
migrating south beyond Africa to "winter" in the perpetual days of the
Antarctic summer on the fringes of the pack ice.
Add to these movements the departures of our Swifts, Swallows,
warblers and all the rest of our summer visitors, and the arrivals (timing
and quantity depending on how hard a winter it is) of all the weatherdisplaced birds from central Europe, and the picture really does become
complex. Nor is it a "once-and-for-all" movement, for should the
weather worsen (or improve) during the winter, additional traffic will


Watching Birds

arise as flocks of birds are affected. The most characteristic examples of

this weather movement, to be seen each year in Britain and Ireland, are
Skylarks, Lapwings and Woodpigeons. Westerly-moving flocks of any
of these species warn the birdwatcher to stoke up his fires!
Now we have some ideas of the benefits of migration to birds in
allowing the colonisation, even temporarily, oflarge areas of the earth's
surface, what are the disadvantages, the hazards of the immense
journeys that may be involved? Clearly predators will be waiting at
every turn. The toll taken of migrant songbirds by man-for
delicatessen use, not to satisfy real hunger-is estimated at many
millions of birds each autumn at the hands of the bird-limers of the
Mediterranean alone. In Africa, one of the falcons has reversed its
breeding season, raising its young late in the summer so that the parents
have easy and profitable feeding on the streams of migrants passing by
Weather, too, must pose problems. Storms can literally knock small
birds from the air, fog and rain can confuse their otherwise brilliantly
accurate navigation. (It is always sobering to remember that in seven
grammes of Chiffchaff is centred a navigational computer capable of
guiding the bird to not only the same country, but to the same county
and the same copse, when it returns next season. All without the aid of
maps and the aids that space-age man finds essential!) Headwinds can
increase exhaustion, and if a sea or desert crossing is involved, this
could be fatal.




18 Lapwing-recoveries during the breeding season of birds ringed as young

in Belgium= B, Denmark= 0, Holland= H, Norway= N, Britain= 0,
Sweden= S
Just as astonishing as the navigational ability is the mechanical ability of the bird as a flying machine. "Fuel" for the journey must be
carried-usually in the form of fat deposits in the body cavity and under the skin. The Sedge Warbler, for example, weighing 12 grammes or
so in normal trim, may feed-up to such an extent before leaving Britain
in autumn that it weighs more than 20 grammes-appearing almost
spherical. In this state it takes off on the journey south carrying, it has
been estimated, fuel enough for between 60 and 90 hours flying-certainly enough to reach Africa in one hop!

Just how do birdwatchers investigate these movements of birds,

perhaps not unjustly described as the miracle of migration, Since
Solomon-"and the voice of the turtle (dove) is heard in our
land"-man has been aware of, and fascinated by the topic. Even so,
only a couple of hundred years ago, Swallows and martins were thought
to hibernate in the mud at the bottom ofponds! At the turn of the century the technique of marking birds with a numbered metal ring was
developed, and since then, with a host of amateur birdwatchers taking


Watching Birds




69' 10'E




Whitefront-recoveries of birds ringed in Britain

Migration 67
part, our understanding of the routes, timing and destination of
migrations has increased immensely.
Each ring (or "band" in America) has a serial number, individually
identifiable just as is a car number plate, together with the return address of the ringing centre. In Britain, the national ringing scheme is administered by the British Trust for Ornithology from their headquarters
at Tring, in Hertfordshire, and rings are marked either with "BTO,
Tring, England" or "British Museum (Nat. Hist.) London SW7". The
second address is most commonly used, and is thought to be more
satisfactory because of the international understanding of words like
"museum" and "London". Details of ringing--the species. its age and
sex, date and place of ringing, are sent to the central files by the ringer,
so that when anyone, at home or overseas, finds a ring, the original
details can be linked with the finding details, the finder informed, and the
"recovery", as it is now called, stored in the data bank-whence it can
be withdrawn to help produce maps such as Figures 18, 19,20 and 21.
Should you find a ringed bird, send all details about it to the address you
find on the ring, or (even if it is from a foreign ringing scheme) to the
B.T.O., who will see that it speedily reaches the correct destination.
The rings themselves (Plate 13) come in many sizes, closely tailored to
fit our birds. The smaller ones are made oflightweight aluminium alloys
and weigh about 600 to the ounce (about as much of a burden to a bird
as your watch is to you). For larger birds, especially seabirds, these
alloy rings wear out before the bird does (many seabirds live for twenty
years or more), and specially strong, corrosion-resistant nickel alloys
have been developed for these conditions.
Naturally the fitting of the ring is a delicate job, requiring a considerable degree of skill and care in handling the birds. In Britain,
ringers must have a licence issued by the Nature Conservancy Council
(a Government Department) as well as a permit from the B.T.O. The
issue of a permit is only allowed after extensive and detailed training in
all aspects of bird handling-usually given at special courses, at bird
observatories, or by selected highly-experienced ringers. Details are
available from the Trust. At the moment, there are about 1300 ringers
in Britain, who between them mark around half a million birds each
year. From these ringed birds, we expect to hear again of something like
14,000 each year, recoveries coming in to Tring from all quarters ofthe
globe (Fig. 22).
Many birds are marked as youngsters, still in the nest, which is es-


Watching Birds

20 Recoveries of birds ringed in Britain-(a) Reed Warbler; (b) Sedge


pecially valuable as they are of precisely known age and origin. The
majority, however, are caught for marking by a variety of techniques,
mostly developed from those used by hunters catching birds for food.
They range (Fig. 23) from the huge Heligoland traps used at observatories to the stick, sieve and string that can be used in any garden. For
ready portability, very fine nets (about the texture of a hairnet, some 9
feet high and from 20 to 60 feet long) called mist nets, originating in
Japan, are unbeatable. Their catching efficiency, erected against a
background of bushes or trees, is very high because they are fine enough
to be invisible to all intents and purposes to the flying bird. So soft and



elastic are they that the flying bird is brought gently to rest before dropping into a pocket, unharmed, to await removal by the ringer (Plate 3).
Bigger birds, such as ducks and geese, can be caught in a more robust
net, which is fired quickly and safely over their heads by means of
rockets or "cannons". This technique has recently been developed to a
very high degree; and amazingly, for some populations of these birds,
between 1 in 10 and 1 in 50 of all the individuals in the world carry a

Ringing is not the only way of studying birds migration. Hundreds of

birdwatchers all over Europe contributed records of their Swallow
sightings in spring so that H. N. Southern's map (Fig. 24) of arrival
dates could be compiled. Again, scattered over Europe is a network of
bird observatories, all situated in areas where experience has shown


Garganey-recoveries of birds ringed in Britain


Watching Birds



..5.000 km at Equator


Arctic Circle ~ - -, -

1 Manx Shearwater
2 Storm Petrel

3 Mallard

4 Wigeon
5 Tufted Duck


White-fronted Goose
Ringed Plover

10 Turnstone
11 Bar-tailed Godwit

12 Knot
13 Ruff
14 Great Sku a
15 Arctic Skua

16 Common Tern
17 Arctic Tern
18 Swift
19 Swallow

20 Spotted Flycatcher

22 Ringing recoveries for some of the bird species ringed in Britain-note the
Arctic Terns offS.E. Australia, more than 10,000 miles (17,000 km) from the
point of ringing





Watching Birds

passage movements to be both regular and heavy. Some are on islands

(like Heligoland and Fair Isle) and many are on the coast. Still others
are situated inland, like the Col de Bretolet high in an alpine pass, or
Radolfzell, on a peninsula in Lake Constance in Germany. Britain has a
/Catching Box

. ......--Baffle
Swing door
Control wire

Catchmant araa


--+---=-Ir----t.:...::..,~-Assambly a~ea

Guide wall

Catchment area


23 The Heligoland trap--note the baffles and the funnel effect of the guide
walls to the assembly and catchment areas



good number of observatories, mapped in Fig. 25, where generally there

is a full-time professional warden, who is helped in his observations,
counting, trapping and ringing by teams of volunteers who may visit the
observatory for a few days or weeks in the spring or autumn migration
Many birds, however, migrate through the night, and such "visual
observation" techniques cannot be applied. However, during the Second World War and afterwards, the scientists who were developing
radar were puzzled by slow-moving belts of interference, looking rather
like a snowfall across the screen. The name "angels" was coined for this
interference, which was eventually found to be due to flocks of
migrating birds. While angels caused problems to military and civil
aviation controllers, ornithologists (under the leadership of David Lack
in Britain) saw in them an ideal method of watching migration after
dark, or when it was too high to be detected by visual observation.
One of the major findings from radar studies showed just how much
migration takes place on broad fronts. It had been thought that migration routes generally followed quite narrow "channels" along leading
lines such as coasts, rivers or hills. Sometimes this is still the case, for
example when storks and birds of prey, which depend on hot-air
currents rising off the land for migration, cross the Mediterranean at
Gibraltar or the Bosphorus, the shortest sea crossing. Generally, even
so, the nocturnal arrivals of migrants recorded from radar observations
are on fronts usually tens and often hundreds of miles wide. Problems
still remain, however, the main one being that the "blips"-the echoes
left on a radar screen by birds--cannot be identified as to species.
Sometimes it is possible to say that they are Buzzard-sized, or Lapwingsized, but rarely more. One species is characteristic: the Starling. The
echoes of Starlings leaving their roosts in the early morning are called
"ring angels"-and look just like the concentric ripples that spread out
after you drop a pebble in a pond. These ring angels have shown
Starlings leaving in all directions from their roost, in batches, spaced out
by very regular time intervals.
For small birds, it is not possible to estimate with much accuracy
how many birds, in a small flock, produce each blip, but the sight of a
radar screen, covering perhaps a circle 100 miles in diameter, wholly
obscures by many thousands of echoes, gives some idea of the really
vast numbers of birds involved in migratory movements.


Watching Birds

24 Swallow sightings in spring, showing the rate of spread of arrivals. The

dotted line indicates the approximate position of the main advancing front on
the dates given (after H. N. Southern)


For over half a century, ringing recoveries have been accumulating.

For some species we now have a fair idea of the pattern of movement,
for other perhaps less common species, this picture is only just
emerging. For example, it begins to look as if the Lesser Whitethroat, a
charming and inconspicuous hedgerow and scrub bird, migrates
southwards in autumn to northeast African countries such as the Sudan
via Italy. The return journey in spring is made well to the east of this
route, through Syria and the Lebanon, and thence north of the Alps to
Europe. The explanation of this "loop" migration is still being sought.
Even for those species that we think we understand, we must not relax,










Bird observatories in Britain and Ireland


Watching Birds

for bird populations are dynamic things and there are (for example) recent indications that Blackbirds may be breeding further north in Scandinavia and wintering further south in Iberia.
I have already indicated that the time elapsed between ringing and
recovery will give some idea of the life span ofthe bird. The table below
lists the known life spans for a variety of species:


Storm Petrel
Manx Shearwater
Tufted Duck
White-fronted Goose
Pink -footed Goose
Mute Swan
Grey Plover
Arctic Skua
Herring Gull
Black-backed Gull
Common Tern
Arctic Tern
Turtle Dove
Barn Owl
Tawny Owl



Great Tit
Blue Tit
Coal Tit
Long-tailed Tit
Mistle Thrush
Song Thrush
Reed Warbler
Sedge Warbler
Garden Warbler
Willow Warbler
Pied Wagtail
House Sparrow
Tree Sparrow





Similarly, we can derive some idea of the causes of death of those

birds reported to us, even though they tend to be rather weighted
towards birds that have died in proximity to man. In this way the
magnitude of the effects of the wreck of the tanker Torrey Canyon and
the subsequent oiling disaster in 1967 could be traced, from recoveries
of auks from all the Irish Sea colonies involved. In the past, hundreds of
British-ringed finches-Linnets, Goldfinches, Chaffinches and Redpolls especially-were caught and caged by Belgian bird-fanciers. Such
figures were used as evidence in the attempts to restrict or, better,
eliminate this sport in the interests of the conservation of these species.
Likewise, for some of our summer visiting warblers (such as the
Blackcap), as many as 25% of the recoveries we receive each year are
reported from the bird-catching regions of the Mediterranean. Of the
very few young Ospreys reared in Scotland under the costly protection
of the R.S.P.B. and other bodies, at least four have now met their ends in
the Mediterranean, shot by "hunters".
It would be quite wrong to close this chapter on migration without
emphasising one major point: despite the obviously giant strides we
have made since Gilbert White's day, we still have no complete solution
to the mystery of migration. How bird navigation works in so many
different circumstances must remain the greatest unsolved biological
problem of our time. There are many theories-too complex to be discussed here--each with some experimental evidence behind it, but for a
full solution, an explanation of the necessary brain structures, and for
the accuracy of time, distance and direction judgements, we must wait.

Lesser Wltitd.hroat

5 Where birds live

"Selborne parish alone can and has exhibited at times more than half the
were ever known in Great Britain."

2 September 1774

Most creatures, except the very unspecialised and adaptable ones such
as man, are governed to a remarkable extent by the nature of their environment. Birds are no exception. A species of bird out of its
geographical range or its habitat is usually an oddity.
This book is written with special reference to the islands of Great Britain and Ireland, and it might be as well, therefore, to describe this part
of the world from the bird's point of view. The British Isles are rich in
bird life. From the point of view of animal geography, they lie at the
edge of one of the most important of the great zoological regions-the
Palaearctic. This zone extends from Britain to Japan, and its animal
(and bird) inhabitants are in the mass different from those in the other
parts of the world. The great region of the Nearctic, which comprises
the north of the American continent, has the closest affinities with the
Palaearctic region, but in many respects the birds, particularly those of
the land, are different.
Of the countries in the Palaearctic region Britain has probably a
larger list of birds than any other oflike area and climate. This is largely
due to the facts that it lies athwart the west coast of Europe, directly in
the path of a major .migration route; that it is provided with many
diverse habitats-large areas of undeveloped marshland alone being
absent; that its northern oceanic cliff-bound coasts attract sea-birds and
others with arctic affinities; and-by no means least-that birdprotection and conservation (with one or two unfortunate exceptions)
are almost second nature to the modern British, and that only a small
group of species is slaughtered for food.
From the point of view of climate, Britain is more favourable to birds

Where Birds Live


than many other parts of the Palaearctic region (Fig. 17). Though
situated in a rather northerly latitude, it is kept warm in summer and
merely cool in winter, by the Gulf Stream; the atmosphere is not too
dry, not too moist; there are no violent extremes of drought or rainfall.
As a result, it has a large population of resident birds, a great number of
visitors which reach it in summer from tropical countries, and many
which visit in winter from the arctic (for even the arctic is cool in
summer, and our winter climate is little different from this) and also
from parts of central and eastern Europe, which although on similar
latitudes to Britain, have winters of continental severity (20C or more
colder than ours!). The great number which visit our country on
passage, in autumn and spring, do so because Britain offers a reliable
and obvious migration route.
Very little of the surface of Britain is as it was before civilisation
came. In the north conifers and birch have given way to moorland, in
the south oak scrub or forest to parkland, plantations, pasture, and
crops. And it is the surface that matters to the birds. In historical times
many species must have come and many have gone, and many have
changed their habits. The following table shows the main features of the
plant-environment in which British birds live.



(1) Coniferous:
(a) Pine (natural).
(b) Plantations.
(2) Deciduous:
(a) Birchwood.
(b) Oakwood-pure or mixed (sandy soil) and oak-birch
(c) Beechwood-on loam (often with oak or ash) or on sand.
(d) Ashwood, often with oak, sometimes birch.
(e) Alder, sometimes with birch and willow species.
(f) Scrub, often hazel, ash or hawthorn.
(3) Mixed:
(a) Plantations, various types.
(b) Beech on chalk with yew and ash.
(c) Birch with juniper.

Most of the above types can be planted or natural; with open or

closed canopies; with or without secondary growth.


Watching Birds







Fringing woods and coppices.


(8) Allotments, small holdings, nurseries, etc.

(9) Arable farmland.
(lO) Grassland.

(11) (a) Lowland (rough pasture, commons)

(b) Acid heaths with gorse.
(12) Upland (sometimes rough pasture).

(13) Mountain tops.
(14) Flowing.
(a) Streams.
(b) Rivers.
(15) Placid:
(a) Ponds and small lakes.
(b) Large lakes.
(16) Stagnant:
(a) Mosses and bogs.
(b) Marshes and fens.





Salt Marsh and estuary.



(21) Built-up areas.

It must be stressed.that this is a general classification of the habitats

of Britain arranged as far as possible from the bird's point Df view. Of
course there are many other kinds of habitat in the world with many
other subdivisions. In the tropical forests alone it is possible to describe
about eight layers, one on top of the other, with a special bird fauna to
each. But such extensions of habitats need not concern us here. Our

Where Birds Live


task is to describe the places birds inhabit in temperate Britain and the
kinds of birds which live in such places. The picture we get will at the
same time give us a good working idea of the situation in North
America, because there the places in nature are roughly the same, and
though the birds that fill them may be of different species, they do much
the same biological work.
To take our first category, we find for instance that the coniferous
forests of America, Europe, and Britain (the last relic of primeval pine
forest is in the Spey Valley) have birds breeding in them which are
strikingly the same, as far as their adaptations to habitat go. A list might

European forests

British forests

(l) Wood Grouse

Willow Grouse
Siskin (different
Crossbill, Parrot
(different species)
Jay (different


(2) Grosbeaks
(3) Siskins
(4) White-winged
(5) Spotted
(6) Nutcracker
(7) Jay
(8) Chickadee
(9) Kinglet

Continental Crested
Goldcrest and

Siskin (as
Scottish Crossbill
Jay (as European,
but sUbspecies).
Scottish Crested Tit
Goldcrest and

The bird population of conifers in Britain is rather interesting

because, except for those in the Spey Valley, practically all our coniferous woods belong to artificial plantations. After the last Ice Age,
perhaps 15,000 years ago, it is probable that pine and birch forest
extended well down to the south of Britain. The birds that lived in those
woods originally spread down with them. Lack and Venables suggest
that they were the Crossbill, Siskin, Lesser Redpoll, Treecreeper, Goldcrest, Coal Tit, Willow Tit, Crested Tit, Capercaillie, and Black Grouse.


Watching Birds

Later the pine and birch woodlands moved north again (at the dawn of
the Christian era it is probable that the only pine forests were within the
Scottish Highlands), to be replaced by the typical oak forest of the
south, and the typical conifer birds were left with two alternatives-to
retreat with conifers or to alter their habits and colonise the oak.
Crossbills and Crested Tits and Black Grouse, among others retreated,
and the first two are now relics only in Scotland (the Crossbills that now
breed in conifer plantations in south England belong to the Continental
race and have come over in irruption years). Treecreepers, Coal Tits,
and Goldcrests, however, have carved out a niche for themselves with
some success in the oak woods; they also are typical birds, of course, of
the southern conifer plantations which have been made by man in recent times. And into these planted pinewoods have also spread some
birds of the broad-leaved woods; these plantations are seldom allowed
to grow old, and in their early stages they are colonised by warblers,
Song Thrushes, Robins, Wrens, and Dunnocks and some exciting
species like Hen Harriers.
Just as there is very little coniferous woodland left native to Britain,
so there is very little deciduous. Practically all the woodland you see in
the country today is planted. Yet whether it is planted or not, we can
recognise many types, each having a fairly distinct bird fauna. An important element of deciduous woodland is what can be generally called
Northern Scrub. It is often composed of alder, often with birch and
many of the different species of willow, and in the untouched northern
regions it forms a fringe between the edge of the coniferous forests and
the real tundra. Iceland and Scandinavia have much of this scrub, but in
Britain it has nearly all been cut or grazed away. The typical birds of
this northern scrub-land are finches like Redpolls and thrushes like
Redwings. There are still plenty of Redpolls nesting in Britain, indeed
they are presently (1973) increasing rapidly (Fig. 26), but with the loss
and cutting away of most of their proper scrub-land, the Redwings have
gone (probably some hundreds of years ago). Today the discovery of a
Redwing nesting in Scotland is usually kept confidential although both
they, and Fieldfares, are spreading very satisfactorily. They are most
welcome re-colonists.
The main advantage which deciduous woodland has over coniferous
is, from the bird's point of view, the presence of numerous holes in
which to nest. The anatomy of a broad-leafed tree tends to permit the
development of holes, whereas that of a narrow-leafed tree almost

Where Birds Live




All habitats



1 0 0 - + - - - - +_ _ _ _ __





26 Redpoll-the rapid increase of this species nesting in recent years, using

1966 as the index (100), is shown by this graph prepared from CBC (Common
Bird Census) reports, published annually in the BTO's journal Bird Study.
prohibits this, especially in commercially managed plantations with an
emphasis on so-called forest "hygiene", where all dead wood is
removed. Often the number of species in conifers is less than in
deciduous woodland, especially if the trees are really densely planted.
Sometimes the total number of birds may be less, but by no means as
often as people think. Conifers do not produce the terrific (but shortlived) peak "crop" of caterpillars associated with oaks, which are used
with superb timing by the Blue Tit and Great Tit to feed their single,
large brood (often between IO and 15) of young, for example. Insect
productivity in conifers is spread over the whole summer and benefits
species with several broods of young.
Mixed woods, plantations of perhaps beech and pine, spruce and
oak, can be very attractive to bird life because of the very large surface
area such plantations usually have. A wood commends itself to birds,
not by having particular types of trees so much as by having a particular physical structure. The important factors are height of main
growth, height and density of secondary growth, whether the canopy is
open or closed, whether there are rides and other spaces throughout the
wood, and so on. An open canopy is one which, when the trees are in full
leaf in summer, admits light in large quantities through to the ground
and the secondary growth. A closed canopy is one in which the light is
shut off from the ground. Generally speaking, the more open a wood

84 Watching Birds
and the more exposed, and consequently better developed and more
diversified, the secondary growth, the greater the bird population. Many
sorts of warblers will sing from song posts on the high trees and dodge
down through the open canopy to visit their nests in the secondary
growth; and the greater the plant variety, the greater the available food,
both plant and insect.
Perhaps the highest bird populations of all are found in areas where
man has interfered with and controlled the distribution and numbers of
trees (see p. 79). The numbers of breeding birds are always high in an
area where there is great variety of cover and choice; and in a garden in
which there are tall trees, shrubs, bushes, undergrowth, nest boxes,
eaves, water, and so on, there are likely to be many nest sites, so that
birds may breed in the garden but forage outside. This island effect has
produced some very high populations in gardens and is now being used
to good effect in modern forestry, where "islands" of old deciduous
trees are left in the midst of the new plantations.
Fringing woods, parks, coppices, orchards, and gardens are artificial
and man-made things, and by no means constitute the environment to
which most of our British birds are naturally adapted. We find these
habitats have been occupied in Britain by such birds as are fairly plastic
in their selection of where to live. Blackbirds and Robins were probably
originally birds of the primeval deciduous woodland, and were not so
specialised, physically or psychologically, that they could not adapt
themselves to the new circumstances. Bullfinches, Hawfinches and
Greenfinches came to the park and garden land from scrub, Pied
Wagtails probably from water meadows.
Before we leave the subject of trees, it is important to note that they
form important breeding sites for birds which otherwise live in open
country. This is perhaps not quite so noticeable in Britain as in parts of
the great central Continental grasslands, where islands and clumps of
trees are full of birds which breed there, but which spread right out
through the plainland when they are foraging. You cannot have Rooks
feeding in your open pastures and arable land unless there are woods for
them to roost in in winter and spinneys and coppices for their summer
rookeries. The only resident Rook in Shetland today is a bird that was
blown there and was tamed by a crofter. There is plenty for this Rook to
eat, but nowhere for it to breed. The most northerly rookery in Britain is
in the most northerly wood, a clump of trees in a sheltered place in

Where Birds Live


Birds tend to feed on agricultural land rather than to breed. But in

Britain such land is bounded and divided by hedges which are so abundant (perhaps as much as a mile of hedge to every forty acres, although
this figure is being much reduced in eastern and southern England) as to
have a very marked effect on the bird population. Every spring the
breeding places provided by these hedges are exploited to the full by
buntings, finches, Dunnocks, Robins, Wrens, Blackbirds, and thrushes.
A few birds like Skylarks find nest sites on the ground in the fields, but it
is the hedges which keep the population as high as that of coniferous
woodland and almost three times as high as that of moorland, heath and
rough pasture.
There are few birds on heaths and moorland, though one or two of
them are specialised and well adapted to their place in nature. Only the
Skylark, Meadow Pipit, Red Grouse and, in parts of Scotland, the
Oystercatcher, can muster an average population of over three birds to
100 acres--compare this with farmland. We have to go down to a density of three birds to 1,000 acres to bring in such birds as the Twite,
Linnet, Reed Bunting, Tree Pipit, Wheatear, Hedge Sparrow, Ringed
Plover, Golden Plover, Lapwing, Curlew, and Partridge.
Some of the birds which breed on the moors, like Curlews, Dunlin,
Golden Plover, h~ve, as their winter places, the wild shores and
mudflats of the coast. Some of these are only just hanging on to their
breeding grounds; today Dotterels nest only on a few remote uplands,
and Whimbrel only in certain rather secret sites on northern isles. All
these moorland birds have to nest on the ground or in such low bushes
and whins as they may find. Even moorland birds of prey such as
Merlins have to nest on the ground.


Watching Birds

On the very high mountain tops, moorland and heath give way to an
Alpine vegetation with low creeping willows and saxifrages. Here the
comer or crevice in the rock becomes the nesting site, and its inhabitants the Ptarmigan, Ring Ouzel or Snow Bunting; sometimes the
Twite. These are probably birds which have had to retreat up the mountains since the world got warm after the last ice age. The Ptarmigan and
Snow Bunting have been almost driven out of Britain altogether, for
they only hang on on the tops of the higher Scottish peaks.
You will not find Dippers or Grey Wagtails away from streams. The
Dipper is adapted in a quite remarkable way for a life in swift water. The
tilt of its back against the running stream enables its feet to get a
purchase on the bottom and control the direction of its movements as it
moves underwater in its search for the larvae of water creatures. Both
the Dipper and the Grey Wagtail nest in crevices and holes, in banks or
under bridges, never far from their water.
One could prepare innumerable lists of birds and the habitats to
which they are restricted. One can assign Kingfishers and Grey
Wagtails to rivers and streams, Coots and Red-throated Divers to
ponds and small lakes, many species of duck to larger lakes, Herons
and Bitterns and Bearded Tits to marshes and fens. On the coast a salt
marsh, sand dune, beach, and cliff have each their own distinctive
fauna. The House Sparrow is as much a symbiote of man as the Jackal
is of the Tiger.
But before we leave the subject of the habitat, we must suggest that its
study in detail means much attention to the psychology and behaviour
of birds. The very interesting work of Lack and others on the reasons
why birds are disposed to select one habitat rather than another has
already made it clear that idiosyncrasies of mind as well as of structure
playa great part in determining where a bird is to live.
Perhaps the most interesting thing that becomes clear is that within

Where Birds Live


one gross habitat like woodland there is a sort of share-out between the
birds. Preferences for things like the height of song posts, open or closed
woodland, type of nest, site, and material and so on appear to be just as
(if not more) important in determining a bird's choice of world as its
food preferences or tolerance of climate. As our knowledge ofthese factors increases, we will surely find that these psychological barriers and
preferences, which birds have, help ensure that the gross habitats can be
divided up in such a way that more varied species can be supported than
would otherwise have been the case.


6 The numbers of birds

"Among the many singularities attending those amusing birds, the
swifts, I am now confirmed in the opinion that we have every year the
same number of pairs invariably; at least the result of my inquiry has
been exactly the same for a long time past. The swallows and martins are
so numerous, and so widely distributed over the village, that it is hardly
possible to recount them; while swifts, though they do not build in the
church, yet so frequr.ntly haunt it, and play and rendezvous round it,
that they are easily enumerated."
GILBERT WHITE, 13 May 1778

James Fisher estimated roughly that there were about a hundred thousand million birds in the world in the 1940s; that is, there are probably a
hundred thousand million rather than a million million or ten thousand
million. Two attempts have so far been made to estimate the total,
month of May, land-bird breeding population of Britain. The first was
that of E. M. Nicholson who, in 1932, put the figure for England and
Wales at about 80 millions. James Fisher's own preliminary figure for
Great Britain, excluding Ireland was about 100 millions (1939). The
table which follows shows a detailed revised assessment of the figures he
arrived at on the latest information available to him in 1946. This puts
the population at about 120 millions.
Since there are large areas of moorland in Scotland (omitted by
Nicholson) and the bird population is consequently low, it can be seen
that the two earlier estimates agree closely; certainly Nicholson must
have the credit for being the first to give an estimate for the number of
land birds in Britain. Both estimates are based, as can be seen from the
table, on sample counts of breeding birds taken in the more important
habitats. Much of the census work has been done by the British Trust
for Ornithology, since 1961 on a greatly expanded basis. In that year
the Nature Conservancy (of which Max Nicholson was the first Director General) commissioned a census of Britain's commoner birds, to be
set up on a reliable statistical foundation and to be repeated each year.
Its purpose is to provide a "population index" for the commoner species
to make sure that no untoward changes were occurring, unnoticed, due


The Numbers of Birds



No. of Birdsper Total No.

thousand JOacres ofbirds
acres 1939 (approx.) (approx.)

Roots, "cabbage", lucerne, etc.
Clover, etc., and planted grasses
Other crops
Bare fallow
Permanent grass
Rough grazing
Deer forest
Other ungrazed moorland
Parks, golf-links, etc.
Small fruit
Gardens, allotments, etc.
Fringing and coppice
Waste, scrubland and swamp
Inland water









to changes in pesticide usage or agricultural practice. Each breeding

season, hundreds of birdwatchers visit their census plots (of between 50
and 400 acres) from 8 to 15 or so times, and record on large-scale maps
the position of territory-holding birds. At the end of the season, these
sightings can be brought together on a tracing and the position and
numbers of the various territories outlined. The results are compared
with the previous years, and population changes over the whole country
can be determined with remarkable accuracy. As a by-product, new
density figures are available, and I have combined data from the Common Birds Census (CBC colloquially) reports published each year in


Watching Birds
Bagley Wood
June 7th 1963
1830-2030 hrs B.S.T.
Visit R

Bagley Wood
Species sheet

27 Bagley Wood-CBC maps showing how individual visit sheets (top map)
can be combined to produce species maps at the end of the season. The species
shown are Whitethroat and Robin, and the technique of marking the cluster of
records to indicate territories can be seen

The Numbers of Birds


Bagley Wood

Species sheet


Bird Study with land-usage and acreage details from Ministry of

Agriculture tables from "Farming in Britain Today" by J. G. S. and
Frances Donaldson and Derek Barber, to produce estimates of the
situation in 1972.

(Arable, mixed inc. fruit)
Rough Land:
(inc. moorland and hill grazing)
Scrub etc.
Forest and Woodland
Urban areas


Millions of Birds per Approx.

JOacres total birds
(approx.) (approx.) (millions)










Watching Birds

The Numbers of Birds

It will be seen that I have used rather broader habitat divisions than
the previous estimates because these fit in better with the nature of the
sample areas surveyed under the CBC. Nevertheless, the agreement
with Nicholson and Fisher is surprisingly close, and the small increase
that it shows is comforting in days when we feel (subjectively) that our
birds may not be faring too well. Here the CBC index figures come to
our aid again, because they show how many of our birds are faring with
the passing years, and with natural changes, such as climate, or with unnatural or man-made habitat change. While many of these may be
described aesthetically as desecration, they may not be as harmful to
many of the more adaptable of our species as we might suppose. The
more specialised birds (for example those of our rapidly dwindling
wetlands) do, regrettably, suffer more severely. But in numerical terms,
if they are excluded, more practically generalised species move in to the
modified habitat-perhaps in greater numbers, so that at this stage we
should be more concerned to maintain a rich diversity of species (which
means a similar diversity of habitat, and retaining, by protection,
workable-sized areas of specialist zones) than worrying about total
In general terms, the mild winters of the late sixties and early seventies have helped population of some of our smaller birds greatly. These
are the ones that suffer in severe frosts and snow-like the Wren, or
the Goldcrest in Figure 28, which gives some striking examples of the
ups and downs of the CBC population index.
Though there are 473 species in the British list, only about 100 of
them contribute significantly to this total and the great bulk of it (about
75 per cent) is made up by 40-odd species. James Fisher thought that
the commonest birds in England and Wales were the Chaffinch and
Blackbird, of which there were about 10 millions each. He reckoned
that there were about 7 million Starlings and the same number of
Robins. Based on CBC results, it is possible to derive some new "league
tables", but these, it must be remembered, can only be the roughest of
estimates. The latest figures (1972) provide a basis for the following estimates of the number of individuals of various species present at the
start of the breeding season:
15 million
8 million

The Number of Birds 93


























Sedge Warbler





Garden Warbler








- - - Farmland


---------- Woodland


28 Nesting populations of 6 species in Britain-graph compiled from CBC

reports over a ten-year period (1966 = 100)


Watching Birds

8 million
6 million
6 million
6 million
5 million
2 million
2 million

Willow Warbler*
Song Thrush
Blue Tit
summer migrants

From this top dozen there are two deliberate omissions: the Starling
and the House Sparrow. Both are numerous and widespread, the
Starling in many habitats, the House Sparrow especially in association
with man, in towns and on farms alike. Regrettably neither lends itself
to census techniques, but my personal feeling is that by now our House
Sparrow population may have ousted the Blackbird from "number
one" spot, perhaps approaching the 20 million mark. The Starling
would, I suspect, feature in the middle orders. A glance at Figure 29
shows that up to 1968, the Whitethroat would probably have been "top
migrant"-clearly it will be many years before it reaches that position
These are the birds with large populations-so large that they can be
arrived at with some degree of accuracy from taking counts of random
samples of the countryside. With birds of smaller populations the







i ..... ~ . . ~,

, Woodland






29 Whitethroat nesting population in Britain for a ten-year period showing

the 1969 "crash"-from CBC reports

The Numbers of Birds

The arrowS indicate severe winters




30 Heron-graph showing numbers of nests in Britain from 1928 and the

effect of severe winters

numbers are so few that, unless one takes a very large sample, the total
population cannot be accurately estimated. Some other method must be
invented for counting them. As far as land birds go, it has only been
possible to count a few populations.
In Britain at the time of the war there were about 150,000 Blackheaded Gulls, a figure which rose to about 200,000 in 1958 and must be
considerably higher by now. These can be included amongst land birds
as so many of the colonies are many miles away from the sea. There are
some 8,000 Herons--and oddly, this seems to be a ceiling figure
(Figure 30). Severe winters cause the numbers to drop dramatically, but
each subsequent rise seems to level out at between 8,000 and 9,000
birds. A 1931 census of Great Crested Grebes showed about 2,800
adults--a repeat, in 1965, showed about 4,500. Possibly this increase
arises in part from protective measures, but more likely it is based on the
tremendous post-war boom in gravel extraction (for rebuilding purposes) and consequent new stretches of suitable water.
It has been possible to count these birds because of the existence of
co-operative observers in all parts of the country (chiefly members of
the British Trust for Ornithology) and because of the particular habits


Watching Birds

of the birds themselves. Herons and Black -headed Gulls nest in very obvious and sometimes spectacular colonies, those of the latter in one case
reaching on occasion nearly 50,000 pairs (Ravenglass, in Cumberland,
which had about two-thirds of England and Wales' population). In
many areas where there are more than a certain number of observers,
these colonies can all be found and counted, and this has been done in
these particular cases, though the Black -headed Gull figures have had
to receive certain mathematical treatment before they could be finally
The only other land birds whose population can be arrived at with
any accuracy have up to now been those which are extremely rare.
Quite often a pair or two of birds are the only ones known to be breeding
in the country and one can arrive at such obvious figures as two for the
population of the Black-necked Grebe in England in 1939, about twenty
for its population in Scotland, and under 250 for its population in
Ireland. Kites are to-day breeding only in Wales, and where James
Fisher could report only four nests, continued perseverance and protection by the RSPB and the Nature Conservancy has resulted in about 20
nests each year at the moment. Despite this protection, even in 1972
eggs were lost to collectors--a sad reflection on our times. How much
more beautiful and useful the birds than their sterilised eggs-contents
blown out, fertile or not, kept as pieces of coloured chalk in secrecy in a
locked cabinet. What is the point?
Some stories are sad ones-in 1946 James Fisher would not have
considered the Red-backed Shrike rare-pairs could be found on any
chalk downland with hawthorn bushes to provide the spikes for the
"butcher birds" larder to be hung on. Now we have perhaps fifty pairs,
and the number falls still. The reasons are difficult to uncover, for
although persecuted by egg collectors, plenty of habitat remains, and
the theory that the appropriate insect food is in short supply is hard to
However, all is not gloomy by any means. In 1946 the two great
success stories had not begun-the return of the Avocet and the Osprey
as British breeding birds. These stories are a triumph for the purposes of
protection-in the one case requiring engineering works to protect the
habitat, in the other electronic devices to protect the nest from those
anxious to obtain eggs.
One rare species has a population which is pretty accurately known.
This is the St Kilda Wren. In 1931 the Oxford expedition recorded a

The Numbers of Birds


total of sixty-eight pairs of this interesting little bird, and the visit paid
by Dr Julian Huxley, E. M. Nicholson, and James Fisher in 1939
proved that no great change had taken place in its numbers.
In 1957, Ken Williamson estimated 120 pairs following a dawn census of singing males, and in 1969, a similar census by David Musson
and Jim Flegg showed about 140 pairs. It might be noted here that the
proper estimation of bird population needs a lot of practice; it is very
easy to over-estimate the numbers of birds, either directly or by
So much for the population of land birds. The numbers of sea birds
are extremely large on a worldwide basis, but not by any means as large
in Britain as those of inland birds. Nobody knows much about the
precise numbers of these birds (except for certain rare species and
others which have been the subject of specially intensive study). A rare
bird, Leach's Fork-tailed Petrel, breeds on only three or four islands off
our coast and probably cannot muster more than 4,000 individuals,
though the true population is difficult to assess, except at night, when
the number can be roughly estimated by the sounds made by the incubating birds in their burrows.
In 1969, our coastal seabird colonies were censused by the Seabird
Group in "Operation Seafarer" (which owed much in its genesis to
James Fisher). The results, published in The Seabirds of Britain and
Ireland by Stanley Cramp, W. R. P. Bourne and David Saunders, show


Watching Birds

the numbers of three species at the breeding season to be about the

million mark-Guillemot, Kittiwake and Puffin-and that the total
seabird population must be well in excess of six million individuals.
By means of a rather complicated mathematical dodge the population (in 1939) of breeding Fulmars in England and Wales was put at
about 480 and in the whole of Great Britain and Ireland at about
120,000. This figure is dwarfed by the continued spread recorded in
Operation Seafarer, when over 300,000 pairs were recorded. There is
only one bird whose world numbers are not small and which are
anything like accurately known. In 1939 a group of ornithologists, including H. G. Vevers and James Fisher, visited nineteen out of the
twenty-two gannet colonies in the world, and were able to make counts
of all but 2 per cent of the birds. They believed that there were about
165,600 gannets breeding in the world in 1939, of which 109,100 bred
in Great Britain and Ireland, and about 11,800 in England and Wales.
All but about eight of the latter bred on the colony of Grassholm in
Wales. The eight come from what appeared then to be a new colony
trying to establish itself on the Yorkshire coast. This now forms part of
the RSPB reserve at Bempton. Operation Seafarer has shown a new
colony in Scotland, and large increases in those already known, to the
extent that the 1939 world population was almost doubled by the 1969
British and Irish figures (138,000 pairs).
Besides the gannet there are relatively few birds with known populations world wide, and most of these are documented in the IUCN
Red Data Book of threatened species. Many must be on the verge of
extinction, like the Japanese Crested Ibis (12 in 1965), Mauritius
Kestrel (10 pairs) and Whooping Crane (33 in 1959, 50 in 1968).
Others, though, have been brought back from the verge. In 1946, Fisher
listed only 50 remaining Hawaiian Geese (Ne ne) but an intensive and
skilfully managed rearing programme using selected parents, at the
Wildfowl Trust at Slim bridge, and later in other collections, has raised
the numbers stlfficiently to allow some hundreds of captive-reared
young to be released again to the wild on a reserve specially purchased
for them on the island of Maui.
In order to establish with reasonable accuracy world population
levels, one or more of the following conditions must be met,
(a) That they are social sea birds with a limited number of colonies
and a definite breeding season, so that expeditions can count the
number of nests at each colony.,

The Numbers of Birds


(b) That they are social birds with a very restricted geographical distribution, and a limited number of colonies irrespective of whether they
are sea birds.
(c) That they are large, spectacular, and easily recognisable birds
(like the Trumpeter Swan and Californian Condor) which are nearly
extinct or which have a relatively small breeding area, in which the
territory or hunting ground of each individual pair can be discovered.
(d) That they are species of birds restricted to small islands.

Darwin once suggested that the Fulmar was the commonest bird in
the world, but judging from its world breeding distribution, James
Fisher was inclined to disagree with him. Modern research has shown
that this distribution is far more restricted than was previously supposed. Certainly the number of Fulmars must not be judged from the
outpost population in the British Isles. In Iceland and the Faeroes, Jan
Mayen, Bear Island, and Spitsbergen there are millions of Fulmars.
There may even be tens of millions, but I should very much doubt
whether there are hundreds of millions. Darwin may have got his idea
from the abundance of the Fulmar at sea in the North Atlantic. Certainly it is one of the commonest birds in that part of the ocean, but James
Fisher suggested that the Little Auk, another arctic breeding species,
runs the Fulmar fairly close if it does not actually beat it. Little Auks
breed in fewer places than Fulmars, but in enormous, closely packed
colonies on such arctic islands as they inhabit.
It is very difficult to assess large numbers. It needs a great mental
effort to think in the necessary terms, and comparative numbers
become as hard to imagine as actual ones. All the same, the most abundant bird in the world is certainly likely to be a sea bird, and probably,
Fisher thought, Wilson's Petrel. Curiously enough this creature has
only been observed in Britain about a couple of dozen times. Its
breeding haunts are the Antarctic and some of the surrounding islands,
and there its numbers, Dr B. B. Roberts says, are quite fantastic. In the
off season, Wilson's Petrel moves into the oceans, and huge flocks pass
up the Atlantic, Pacific and Indian Oceans, and even into the Red Sea.
As they get north they tend to congregate on the west side of the Atlantic, reaching their peak in numbers in our northern autumn in the
neighbourhood of Long Island. There are probably one or two other


Watching Birds

seabirds which may run Wilson's Petrel fairly close: these are the Cormorants of the Cape and of the Guano Islands of Peru.
It is possible to guess at the most abundant land bird. It may lie
between the Starling and the House Sparrow, but the enormous
numbers of some of the weavers (Quelea) in Africa should not be
overlooked. Their flocks are so huge (sometimes a million or more

House Sparrow

strong) and so mobile that accurate assessment is unlikely. Both House

Sparrow and Starling have origins in the European continent, where
they are very widespread, and have been transferred by human agency
to other continents. In North America both Starlings and House
Sparrows are pushing rapidly westwards, where they are in many
regions becoming dominant birds. The House Sparrow is getting to
other parts of the world as well. It has reached Uruguay and arrived at
the Falkland Islands in 1919. It was introduced into New Zealand in
1862, and into South Africa at the end of the nineteenth century.
Though the House Sparrow has now a wider distribution in the world,
the Starling has probably the higher population, since it is not so
restricted in its habitat.
The most widely spread land bird in the world is pretty certainly the
Barn Owl. Its races extend to every part of the world except the polar
regions and New Zealand and certain of the Pacific Islands although it
has penetrated as far as Fiji.

There are two main methods of counting birds, the area census and
the breeding count of an individual species. Both methods are valuable
for finding actual populations and for comparing the situation in

The Numbers of Birds 101

different years. Again we must emphasise that our general idea oflandbird breeding population has been arrived at from the first method,
which is perhaps the most important. The general technique is to take a
sample of one of the major habitats, to find the area of this sample, and
to find the total number of breeding pairs of all species in it. In the long
run the only absolutely accurate method is to find every nest, a method
which needs much skill and practice and which, in honesty, is never likely to be achieved over a suitably-sized area.
Most of the intensive work on the bird life of farmland, woodland,
moorland, and so on in Britain, is being done by members of the BTO,
using the CBC techniques described earlier, and we have a picture of the
relative abundance of the different kinds of birds which is a good deal
more accurate than our idea of their actual total numbers. Of course,
relative numbers are of great biological importance, so it is not surprising that much work and thought has been given to their discovery.
The simplest method of all is to walk through a selected part of the
habitat and make a tally-list of the species and the numbers of each seen
or heard.


We have already suggested that most of the counts of individual

species of birds have been successful when the birds have been social
breeders. This particularly applies to sea birds. The main task of the
Gannet-counting teams during their world survey in 1939 was not so
much the actual counting as getting to the colonies. In this particular
case the colonies are on the remotest possible stacks and rocks (see


Watching Birds

Plate 2), like Eldey, 20 miles from the nearest fishing village out in the
Atlantic off the coast of Iceland. St Kilda is 45 miles west of the outer
Hebrides. Sula Sgeir is about the same distance northwest of Cape
Wrath. Sule Sack is about 35 miles from Cape Wrath and the same distance from Orkney. The Hermaness (Muckle Flugga) colony is the
northernmost tip of the British Isles. Once the colonies have been
reached, there are certain further technical difficulties, such as those of
landing and climbing, but the task of counting each occupied nest is
comparatively simple, though it imposes a certain strain on the eyes.
Most people who visit a place where birds are breeding carry away
some impression of population. Usually this is interpreted in their
notebooks as few, common, abundant, and so on. It needs little extra
effort to make these notes entries less vague, and one's rapid impression
can quite easily be translated into terms of under ten, under 100, under
1,000 (and so on) breeding pairs or breeding birds. Of course, notes on
actual numbers are far more useful than notes of the above kind, but
those general figures are far better than no figures at all, and can often
be interpreted to a good deal of advantage by somebody who is working
up the particular species later. Our knowledge of the Fulmar's increase
in population (as opposed to its simple geographical spread) is largely
due to interpretation of observations in terms of under ten, under 100,
and so on.
We have already noted that the numbers of birds fluctuate, often in
an orderly and remarkable way. In Chapter 4 we have discussed some
of these fluctuations, especially those of species like the Crossbill and
Pallas's Sand-grouse, and Figure 28 has shown us others. We should
not forget the nature and size of these fluctuations when making comparisons. Nevertheless, there are many trends in the numbers of British
birds which we cannot yet ascribe to periodic fluctuation. Some species
are tending to increase and spread, others to decrease and disappear
from their previous haunts.

Perhaps the most spectacular spread in recent years has been that of
the Fulmar. In the year 1697 this bird was known to breed on the
islands of St Kilda, and though there are one or two early records of
colonies elsewhere, none of these can be really substantiated. In 1878,
however, a colony established itself in Shetland on the island of Foula,

The Numbers of Birds


and since that date the number of known colonies has increased to such
an extent that in 1939, 208 different stations were known at which birds
were definitely breeding, and 61 others at which birds were present in
the breeding season but had not yet been proved to breed. The spread
took place, first, to the more oceanic headlands, followed by the
colonisation of the intermediate cliffs, and a gradual pushing up the
firths and locks. Down the coast of Britain Fulmars reached the limit of
high cliffs in Yorkshire in 1922; by 1940 they were prospecting the
lower cliffs of Norfolk, and in the breeding season of 1944 were seen at
cliffs in Kent. In 1944, too, they first bred in Cornwall and on Lundy
Island off the Devon coast. At about this time, they were seen, in
summer, at cliffs in Dorset and the Isle of Wight, and were present every
year in Pembrokeshire; they had pushed down the North Channel into
the Irish Sea, and bred on the Isle of Man and in County Dublin. They
were present in the breeding season at Holyhead, and bred in 1945 on
Great Orme's Head. In Cumberland they first bred in 1941, at St Bee's
Head. They have pushed up the Inner Hebrides from the south. The
series of maps in Figure 31 shows roughly the way their spread has
taken place.
Most of the colonies, except for some in the very north of Britain, are
still small; their numbers have increased much more rapidly than the
total population of Fulmars, which has trebled in its sixty years of imperialism. This trebling is, all the same, remarkable, since the Fulmar
usually lays but one egg a year and rarely replaces it if it is broken or
lost, and it may only breed once every three years. At certain times the
increase has been at over seven per cent compound interest, and
through most of the time at over three per cent per annum.
The causes of this remarkable change in numbers and distribution is
not properly known. It was recently suspected that the increase might
have been due to an overflow from St Kilda, since at roughly the time it
started the St Kildans began to receive supplies of food from the
mainland and were supposed to have discontinued their famous fowling
habits. But an exhau~tive survey of the literature about St Kilda, which
is very complete, shows that, until 1910 at least, the St Kildans went on
taking birds as much as ever. Moreover, it is becoming clear that the
Fulmar started spreading many years before the first new colony was
established in Britain. The spread dates, from about 1816, when the bird
began to increase greatly in Iceland, and some time between then and
1839 it arrived at the Faeroes, north-west of the Shetlands. In the


Watching Birds



.. .


The Numbers of Birds

Number of breeding pairs per vice-county







Present in

season, but

Under not yet proved

to breed

31 Fulmars-maps to show the spread of breeding in recent years-inset in~

dicates breeding range (not numbers) in 1972 (from John Parlow's Breeding
Birds of Britain and Ireland)


Watching Birds

Faeroes it spread so much that the inhabitants were taking and eating
100,000 young a year, which was very much more than the total
number of young produced in one year in Britain. In 1936 this taking of
young Fulmars was stopped, since an outbreak of psittacosis was
traced directly to the birds. Writing on the situation in 1966, James
Fisher expressed his conviction that the prime cause of this expansion
was the increasing provision of fish offal from modern fishing fleets,
with the majority of the catch gutted and frozen or salted at sea.
There have been many other recent and remarkable spreads of
species of birds in Britain. The Little Owl, which was introduced into
Britain (in Northamptonshire) in 1889 and in Kent in 1896, has now
spread to every corner of our country, as far north as Lancashire and
Yorkshire. It reached Norfolk in 1912, Land's End in 1923, Pem
broke shire by 1920 and the Pennines and North Wales by 1930. The
reasons for its spread are relatively clear. It was a Continental bird from
mid-Europe, separated from our country by wide natural barriers. Once
these had been overcome by importation the bird found that the place it
occupied in nature in its native haunts was not occupied strongly by any
bird in Britain. Without competition, its increase was assured.
There have been some signs of recent invasion from the Continent by
one or two species which seem to be generally extending their range in
the west. The Avocet and the Osprey have already been mentioned, but
the Black Redstart seems to be arriving in increasing numbers year by
year, and every season brings new records of its breeding in southern
counties. It has bred in the heart of London since 1940. The Stock Dove
has invaded Ireland presumably from England and Wales: since 1875,
when it was first noted, it has increased and spread, till to-day it is
breeding in nearly every Irish county. At the same time this bird pushed
into the north of Britain and invaded Scotland. To-day it breeds in the
west as far as Argyll and on the east right up to Sutherland.
Two wetland warblers are new arrivals, Savis Warblers arriving in
Kent in the 1960s, and breeding there and in other south-eastern counties (but in low numbers still), and more recently Cettis Warbler. This
latter is a non-migratory warbler, and thus its tenure in Britain will depend much on future winters' severity. In the last three years it has
cropped up, with its noisy song, in a number of south-eastern localities
and perhaps a couple of dozen pairs are now breeding.
The success story to cap all others concerns the Collared Dove: from
first sightings in Britain (greeted with great scepticism) in 1952, to first

The Numbers of Birds



32 Greater Spotted Woodpecker-spread of this species during the last hundred years


Watching Birds

breeding in 1955, the Collared Dove has since conquered all of Britain
and Ireland, breeding even on the west coast islands of Ireland, occurring regularly on remote St Kilda and now breeding in Iceland! All in
the space of 20 years. Quite what lies behind this westward surge, is uncertain. Presumably once in Britain, it found no competitor strong
enough to deny it its chosen niche, but what caused the original eruption
from the eastern end of the Mediterranean, colonising the whole of
Europe? Perhaps a sudden genetic change-but then how did this
spread so rapidly through the population?
The Greater Spotted Woodpecker is another bird which is pushing its
range forward. In recent years it has become very much more common
in the north of Scotland. In 1939 it was definitely recorded from a wood
in Sutherland not far from the Caithness border, and lately it has been
spreading through Argyll (see Fig. 32).
Many other examples of increase of range might be quoted, and
examples of species which are finding new habitats as well as new lands
to conquer. Thus Curlews have increased and spread onto relatively
low ground in England in the last twenty years. Black-headed Gulls are
tending to breed more widely inland, and are to-day land birds as much
as sea birds. Their numbers are increasing too as we have seen. In the
north of England and Scotland, Oystercatchers have spread up the river
valleys and are breeding many miles from the seashore. Reed Buntings
are becoming more and more birds of scrub; occasionally, woodland
and even gardens in winter (where they favour bread!), and the Siskin is
now a regular attender at many garden peanut holders.

In 1968, the BTO launched possibly the biggest birdwatcher participation exercise ever, when a five-year programme to visit all the
3,850 ten-kilometre squares of the National Grid and to record their
breeding birds was started. Amazingly, the target of complete coverage
was achieved by 1972, and so far as can be judged the standard of
observations was very high. Each "square" surveyed meant
preliminary consultation of large-scale maps to find the best-looking
sites and to ensure that all habitat types were covered, and the planning
of an effective survey-route. During the breeding seasons, visits were
made in different months and at different times of day. The techniques
evolved are now becoming standard practice for birdwatchers visiting

The Numbers of Birds


33 Provisional distribution maps from the BTO atlas of breeding birds: (a)
Redwing; (b) Tree Sparrow; (c) Kingfisher; (d) Collared Dove


Watching Birds

new areas, and many observers have been startled to find just how
prolific were parts of their own parishes that they had not bothered to
visit. Figure 33 shows some interim examples of the maps now being
produced. Not only were they the basis of some most enjoyable birding,
but the final product will be of great biological interest. For
example--what are the features which produce a northwesterly distribution for the Pied Flycatcher, a southeasterly one for the
Nightingale? Why is the Corn Bunting so erratically distributed, and
what causes the Yellow Wagtail to be a water-meadow bird in one county and a potato-field bird in another? Certainly in this sense, the maps
and all the possible correlations with geological features, vegetation,
climate and land use, will pose more questions than they answer. From
the conservation point of view, the breeding situation of Britain's birds
will be "frozen", and this frozen picture will serve as a yardstick against
which future changes can be assessed. Already the scanty remnants of
the once-widespread distributions of Wood lark, Nightjar and Cirl Bunting have been revealed, showing the areas in which these species are in
need of protective measures, and where such measures can sensibly be

Some of the causes of population spread are hard to define. So are

some of the causes of decrease. It is difficult to imagine why it is that
Wrynecks have become so increasingly rare in the last few
years-though it has been plausibly suggested that this is due to the cutting down of old gnarled orchards and the planting of standard apple
trees; that is, to the destruction of many of their favourite nesting sites.
It is difficult too to explain why Rock Doves are now no longer breeding
in England or Wales or on the east coast of Scotland south of the Firth
of Forth.
Many of the decreases of British birds are, however, attributable to
human agency. These causes, it should be stated, are in the long run
often deep-seated and probably out of the control of the conservationists. It was the draining of the fens and not the absence of bird
protection laws which lost us Cranes and Spoonbills as breeding
species. The cutting up and working of plains-land by man drove out the
Great Bustard as a breeding species by 1833; and is now making the
Stone Curlew a rarish bird, breeding on such barren downs as it can still

The Numbers of Birds


find. It is highly likely that one of the most spectacular recent decreases,
that of the Corncrake, is due largely to human agency; the results of a
British Trust for Ornithology investigation (in which about 2,000
observers took part) showed that the development of the modern
mowing-machine, together with the earlier date of grass-cutting in more
intensive forage cultivation (at least three weeks in advance compared
with 50 years ago), has been very closely linked with the Corncrake's
disappearance. An enormous number of Corncrakes and their young
must have been killed by the mowing, and the changing patterns of
agriculture must discourage many others.
The main task of those concerned with bird protection seems to be
threefold. First, their job is to ensure the continuance of certain areas in
their present natural state so as to preserve a sample of bird life as little
affected by man as possible. Secondly, their task should be to preserve
the different species of birds because of their population, interest, and
biological importance as much as because of their rarity. Thirdly, they
have to keep the collector away, particularly from such species as are
on the verge of extinction. There is no need to fear anyone in saying that
the extinction of a species should never be ascribed to collectors in the
long run, though they may often be the last straw. The fact that the
remaining pairs of Kites to-day are jealously guarded from collectors
by a private army of enthusiasts certainly does not mean that collectors
alone have brought matters to their present state. The trouble is that
when for various reasons a bird becomes rare, its importance and the
importance of its eggs from the collector's point of view become correspondingly greater, so that its end is hastened. If collectors were finally prevented or educated away from breaking the law, as we must hope
they will be, it is possible that a remnant of many species now nearly
extinct would be saved. But it is equally probable that this remnant
would seldom become anything more than a remnant, and that while it
would remain very interesting from a human viewpoint, it would never
playa serious biological part in our bird fauna.

It is possibly apt to make some remarks in this chapter about the

organised protection of birds. First we must realise that in this country
we have inherited a wonderful bird fauna. It is rich in species, rare and
common, of simple and curious habits, harmful and beneficial, dull and


Watching Birds

exciting. When we consider the preservation and conservation of this

heritage of birds, we must have several attitudes in mind, and we must
be careful that our special fancy for anyone of these attitudes does not
lead us to neglect the weight of the others. Our attitudes must be
biological, scientific, economic and aesthetic. We must only allow
ourselves to be sentimental in so much as it allows us to satisfy the other
more important attitudes. We must see ourselves first as animals living
in this country in an ecological relationship with the wild creatures
around us.
If a SOO years old tradition encourages men from the Isle of Lewis to
make a hazardous boat journey every year to take young Gannets on
Sula Sgeir, we must try to arrange that they are able to pursue this, to
them, important and economic custom. We must not say this killing
must stop; neither must we say that we can leave the future of these
Gannets to chance. Our solution is to apply what knowledge we have of
the vital statistics of the Gannet, and to ration the numbers taken for the
benefit of both man and bird. The men of the Faeroes, who take
Gannets every year from the Holm of Myggenaes, farm their birds as
carefully as if they were chickens.
Most of the common small birds of the countryside are probably
beneficial in the long term, and if the amounts of good and harm done to
human agriculture and enterprise by birds as a whole are totted up, they
come out about level, or better. The harmful birds comprise relatively
few species, though these do altogether as much harm as the many
beneficial species do good.
The biological value of the Rook is very imperfectly understood.
Quite serious controversies still rage about whether it is ultimately
beneficial or injurious. Certainly the most injurious bird in Britain is the
Woodpigeon, although the House Sparrow may by now be catching up,
with its haul of ripening cereals. The Woodpigeon probably does much
more harm than the most beneficial bird does good.
The aesthetic argument is the stimulus behind practically all the bird
protection that has been organised by law and active deed in this country. Among the many facets of this argument, a new one is becoming
important-that birds should be preserved, not only because of their
rarity, curiosity, wildness, or romance, but also because of their
biological interest and because of their involvement in the complex
inter-relationships of the web of life. This new argument contradicts
some of the old ones, for many of the predatory birds disliked by

A Puffin from a specially marked population on St Kilda. The numbered

B.T.O. ring is on its left leg, and a coloured plastic ring, with etched letters LULU,
is on the right-the lettering can be read through binoculars at a considerable
distance. With rings such as these the diminishing population can be more easily
studied in an attempt to understand the causes of its sad and rapid decline. (Jim

2 The Gannet colony on Grassholm, off the Pembroke coast. Note the precision-spacing of the incubating birds, each two-beak 's
distance from its neighbour. (Photo : Jim F legg)

3 A line of mist nets set in a woodland clearing. Note the net in the left foreground, which stretches away well beyond the ringers. (Photo : Jim Flegg)
4 A cb.ardonneret garden trap which has caught a Greenfinch coming to peanut
bait. The other cell remains set and the trapped bird may tempt another to enter.
(Photo : Jim Flegg)

5 The skilful and quite gentle process of extracting a Tree Sparrow from the mist
net. (Photo: Jim Flegg)
6 The ringer now has the bird comfortably held in such a way that it cannot
struggle. (Photo: Jim Flegg)

The Numbers of Birds


sportsmen and sentimentalists are of primary interest to biologists.

It is worth quoting James Fisher's views (in 1946) in fuIl: "In my opinion those who have framed the policies of bird protection societies and
who have drafted the standing orders to watchers of sanctuaries, have
not fuIly asked themselves the whys and wherefores of their protection.
They have not always decided what birds they are going to protect and
what they are going to protect them from. The public mostly thinks of
protection as being bound up with sanctuaries, and indeed most of the
work of societies like the Royal Society for the Protection of Birds is
concerned, when it is not enforcing the existing laws, with the management of smallish areas of land for the benefit of birds. Some of these
sanctuaries are probably below the minimum size in which active
management would really pay by producing the goods (whether the
goods be more rare birds or better places for birds to live in). But many
of them succeed in keeping mischief-makers away from birds which are
particularly interesting, on the threshold of existence, or which are of
some special sentimental importance.
"It should be stressed that bird protection can never be reaIly efficient
until sanctuaries can become national parks, individual problems
become local problems, and local problems become national problems.
We cannot really know what is to become of our birds, and from this
knowledge manage them, until we treat them like any other national
commodity such as sewers or the unemployed or electricity."
Clearly, since then we have made giant strides. But have we as individuals (let alone as a nation) reaIly assessed the problems yet? Have
we come to terms with the situation and accorded priorities, and above
all are we ready to pay the going rate to operate a conservation policy? I
feel stiIl that in many people the emphasis is wrongly placed-the "rarity value" and "zoo appeal" of bird and reserve alike remains more important than the aesthetic needs, demanding wide, unchanged acreages
or the ecological demands that the so-prevalent trends towards
mono cultures (or at least oligocultures) should be slowed or halted. For
their part, the ecologists who are at present in some danger of being
over-run by public awareness and concern-the "environmental
revolution"-must continue to work to produce factual evidence in
support of their theories, however difficult and time consuming the
tasks. In the long run, an over-played hand can be as dangerous as
We now have legislation on the lines propounded by James Fisher in


Watching Birds

1946, but it is still confusing, and still difficult to apply. The RSPB are
to be heartily congratulated at beating both the offender and the treacle
tart of the law in each successful prosecution. But how much better it
would be if we felt concern for our birds (and of course all wild things,
plant or animal), regarded them with proper concern (for their ills may
foretell ours, as does the miners' canary) and considered this complex of
islands as one whole nature reserve, treated with consideration and
despoiled as little as possible. We complain of the lack of a national
strategy to guide and rationalise planning, to eliminate the running sores
of hotch-potch development: is this lack a reflection of our disinterest,
or inertia, or selfishness? We all use petrol, but none of us want an oil
refinery nearby!




!leatCrestcd crebe

7 Disappearance and defiance

"The note of the Whitethroat, which is continually repeated, and often
attended with odd gesticulations on the wing, is harsh and displeasing.
These birds seem of a pugnacious disposition; for they sing with an
erected crest and attitudes of rivalry and defiance; are shy and wild in
breeding-time, avoiding neighbourhoods, and haunting lonely lanes and
commons, nay, even the very tops of the Sussex Downs, where there are
bushes and covert."
GILBERT WHITE, 2 September 1774

The frontiers where the world of birds impinges on that of man are
largely those of emotion and symbolism. The ordinary child or man
with a normal interest in birds thinks first of them as singing, or building
nests, or chasing each other, or flying in excited flocks-as doing, in
fact, the things that are the most highly symbolic or stereotyped of all
their habits.
Many of man's habits are highly symbolic, and though born no doubt
for some useful function, have, in the course of time, lost much of their
immediate use. Yet they are retained, since they fulfil our emotional
needs. Such habits are singing, dancing, telling stories, making puns and
jokes, a lot of smoking, the curious, interesting, and rather pleasant
behaviour known as "manners", and much religious behaviour. Mostof
these habits are instinctive (a word which must be used with care) and
few are intelligent-though that need be no reason for deserting them.
Birds have no intelligence to speak of-in the way in which we popularly understand the word. Their emotional, instinctive, and symbolic
actions are correspondingly all the higher and more important. In many
ways their very emotionalism is robot-like. Their world is so narrow
that normal life presents them with a very limited number of
situations-and the number of possible responses they can make isjust
as limited. It is not surprising, therefore, that when presented with a
situation quite unknown in their normal life, birds should react by doing
something which does not fit (but which is itself normally a reaction to
something familiar to them). Thus a gunshot may startle birds in a wood



Watching Birds

into full song; a man, suddenly intruding, may find Adelie Penguins
offering him stones, nesting Stanley Cranes offering him sticks,
pheasants in captivity may court their food-troughs or their keepers. If a
man had a bird's mind he might quite well be given to reciting "The Boy
stood on the Burning Deck" (or some other more suitable epic) at a
smoking concert, but might also recite it in an air-raid or an earthquake.
Within the web of the bird's own ordinary life, its limited repertoire of
actions and reactions suits it very well; and as so many of its habits of
life are symbolic, like song or courtship, and for that reason curious and
interesting to us, we must make some effort to examine them.
The symbolic actions of birds-those actions designed to appeal or
signal to other animals in their immediate world (whether birds of their
own kind, other birds, mammals, including man, or any other sorts of
animals)-may involve sight, sound, or touch, but rarely smell (birds
have very little sense of smell). When these actions involve some sort of
posturing, in which colour, shape and adornment may be used, they are
often called displays.

One of the most interesting ways in which birds "signal" to other

animals is a purely negative one-in the sense that it is the opposite of
signalling. It is the habit of concealment. At different stages of their
lives, many different sorts of birds have concealing colouration, which
enables them to "disappear" into their immediate environment and thus
hide from their enemies, or even, in the case of (say) the Tawny Owl, to
blend with their surroundings so that potential prey, unawares, approaches their perch sufficiently close for the owl to "parachute" down
onto it. Many British birds show concealing colouration or shape.
Examples are:
Eggs-Those of the Ringed Plover, laid on stony ground, resemble
coloured pebbles, and are very difficult to see (Plate 12). The eggs of
the Lapwing (another ground nester) have a camouflage pattern which
breaks up their outline. Many other waders and gulls have eggs with
similar protective colouration.
Nests-Most land birds hide their nests, many by concealing them in
thick bushes, in leafy trees, in long grass, and so on. But some go
farther, and build their nests to resemble some of the special, rather than
the general, features of their environment. Thus a Wren may cover its

Disappearance and Defiance


34 Nest of the Ceylon Black-backed Pied Shrike built to resemble a mossy

branch stump, with young birds seemingly part of the branch outline

Young Birds-Many fledglings, particularly those which leave the

nest as soon as they are hatched, have protective colouration consisting
often of a disruptive pattern which breaks up their outline. Newly
hatched Oystercatchers, Ringed Plovers (Plate 12), and terns are almost
invisible. Young Ringed Plovers also have a "signal" patch of white on
the back of the head, which is clearly visible when the bird is upright
with neck stretched. If, when frightened, it crouches, the patch is
Adults-Partridges, hen Pheasants, Woodcock, Snipe, Bitterns,
Nightjars (by day), and several other birds have concealing colouration
by means of which they blend with the general surroundings. This
property is chiefly brought into use when the bird is on the nest. The
Poor-me-one on its nest usually looks as much like a branch-stump as
the young of the Shrike in theirs, and the Bittern, black-striped, neck
erect, beak pointing skywards, blends into the reeds if surprised whilst
Bluff-Many weak and inoffensive birds defend themselves against
possible enemies by means of bluffing. Often, people are suspicious of
hissing from hollow trees or nestboxes, feeling that a snake may be inside. In nestboxes, the "snake" may be a Wryneck, stretching out its
neck and hissing as hard as it can, and tits and owls (and even


Watching Birds

Goosanders) will hiss in an intimidating fashion when their nests are

Mimicry-Among the animal kingdom we find examples of the
mimicking of distasteful or pugnacious animals (models) by harmless
ones. As long as the mimics are fewer than the models, this works to
their advantage, since predators, when sampling the group, are more
likely to capture a model and be thus disinclined to repeat the performance. In Britain we have no good examples of birds with these
characteristics, though in Madagascar we find harmless thrush-like
birds mimicking pugnacious shrikes, and in the East Indies orioles
mimicking Friar Birds. It is possible (though not very likely) that the
Cuckoo's superficial resemblance to a hawk may intimidate the birds
whose nests it intends to parasitise.

Charles Darwin thought that bright and startling colours in male

birds were adaptations for attracting females. He thought that they had
evolved by sexual selection; that is, that the choice of mate rested with
the females, and that those males which were most attractive to them
would be most likely to get mates and perpetuate their characters
through their offspring. It is probable that a great element of sexual
selection is found in bird (as in most animal) evolution; but it is equally
probable that the bright colours and adornments of certain birds have
as their primary biological purpose intimidation and threat rather than
attraction. This applies to all birds which have bright plumage, whether
it be only in the male (like pheasants and some buntings), only in the
female (like phalaropes), in both sexes all the year round (like Robins
and Jays), or in both sexes in the breeding season (like Black-headed
Gulls). Examples of the use of colour and adornment for the purposes of
intimidation are:
Brightly coloured males-On the strict Darwinian view it would'
appear likely that the summer plumage of male Ruffs was a simple
product of sexual' selection. The ruff is one of the most curious waders;
in the winter it is of the same build as, and not unlike, a Redshank or a
Bartram's Sandpiper, but in the summer the males develop tremendous
ruffs of feathers on the head and nape, which fold over the neck, and
which, in full display (Fig. 35), are erected to form a circle of bright
colour surrounding the head. From March to May anybody can see

Disappearance and Defiance



Ruffs in aggressive display (drawing by James Fisher)

male ruffs in full plumage and display in the Waders' Aviary at the Zoo,
and prove for themselves the undoubted fact that no two ruffs are alike.
I know of no bird, and certainly no wader, in which such individual
variation of male aggressive plumage exists, for the function of the ruffs
is intimidation rather than attraction. In the breeding season Ruffs congregate at special meeting-places, usually called Ruff "hills" or "leks".
On these hills the males display and threaten with fully expanded ruffs
and ear tufts, not at the females but at each other.
Battle is much too symbolised to allow much loss of blood or
feathers, but occasionally real scraps will develop. The males crouch
and face each other, beak to beak and with ruffs spread, or chase each
other to and fro from the little areas of the hill that each seems to call his
own territory and defend as such. It appears that bluff has been largely
substituted for beak and claw fighting, a bluff accentuated and assisted
by the brightness and extent of the ruffs. The females (Reeves),
meanwhile, wait quietly in the wings. She certainly appears to select her
mate (for the males are completely promiscuous), and walks over to
him, crouching in a submissive posture and touching him with her beak
before mating takes place. The female after mating sees no more of the
male. She selects the nest site, builds, lays and raises the family. Females
disperse some distance away from the leks to build, which is an additional defence against predators.
Blackcock breed in certain parts of Britain (unlike Ruffs, which were
only known to have bred once between 1918 and the sixties, but now


Watching Birds

breed most years}. Like those astonishing waders, they have meetinggrounds (also called leks) on which they congregate. At these meetinggrounds male Blackcock have three kinds of display-first, crowing
and jumping, which appear to be a mutually-stimulating affair; secondly, the highly aggressive "rookooing" in which, to use Lack's description, "the male stands with head and neck thrust forward, the neck enormously swelled, and utters a musical, bubbling dove-like 'rookooing',
often in long continuous phrases, the whole body shaking with the
calls," and at the same time the lyre-shaped tail is spread, the wings are
dropped to show patches of white, and the red waffles fully distended-as they are in all forms of the Blackcock's display; thirdly, the
circling, crouching courtship which often ends in copulation with the
At Blackcock leks the males all hold small territories to themselves;
the object seems to be to prevent other birds from interfering with the
male when he is copulating with the female. The whole system of the
Blackcock's sexual behaviour centres round this territory; were it not
efficiently secured and defended, he would have little sexual success.
Hence the importance of his striking plumage, his use of it in display,
and his song (for this is what "rookooing" is). That his plumage is used
in a socially stimulative display, and that it is used in a courting display
directed towards the female, once she has walked into his territory,
seems to be a secondary matter. The Blackcock's intimidation display is
not necessarily all bluff; sometimes mortal combats take place. This is
wasteful, of course, in the biological sense, but seems to be quite rare
once the male has established his territory.
The Snow Bunting IS a bird which nests sparsely in the north of
Scotland, and widely in the Arctic. It is a monogamous bird (though occasional polygamy has been noted), and the male in breeding plumage,
with his attractive black and white colouration, contrasts strikingly with
the brown and white female. Though his contrasting colouration is
brought into use in special display ceremonies devoted only to his
female, its primary function appears to be one of threat (see Fig. 36).
When the male has arrived in his breeding territory in spring and notices
another Snow Bunting, whether male or female, approaching his
territory, he goes back at once into a threat attitude. He faces the intruder, lowers his head between his shoulders, and utters a sound which
Tinbergen writes as pEEE, and likens to the sawing note of the Coal Tit.
If the newcomer alights in his territory he flies towards it, singing in

Disappearance and Defiance


flight, and rising steeply with his body curved upwards and his wings
trem bling. Only when he is near the other bird does he distinguish, by its
reaction to his approach, between male and female. lethe intruder is a
male, a struggle may result; if a female (and he is unmated), a courtship
display. Here then is a case of a first general reaction being entirely one
of threat, continued as such if the other bird is recognised as a male, and
substituted by a courtship display only when, at close quarters, the newcomer is recognised as a female.
To observe Ruffs in any numbers in natural surroundings it is
necessary to go to Holland; Blackcock leks are few and far between;
Snow Buntings take a lot of finding on remote Scottish hilltops; we must
therefore find another example a little nearer home. Let us examine the
Reed Bunting as described in Eliot Howard's An Introduction to the
Study ofBird Behaviour. Eliot Howard (who will be mentioned a good
deal) has given us a picture of its behaviour whose accuracy of description is only equalled by its quality of prose. Though we cannot quite

36 Snow Bunting-display attitudes: 1, 2 threat; 3, 4, 5 song flight; 6
territorIal fight; 7 calling on arrival in territory; 8 display to newly arrived
female (drawings by James Fisher)


Watching Birds

compare his account step by step with Tinbergen's description of the

behaviour of the male Snow Bunting, we can find in it enough to tell us
that the male Reed Bunting, no less than its arctic counterpart, lives a
spring life in which intimidation, aggression and territory occupy its
mind to the exclusion of almost every other instinct. Intimidation
(Howard calls it excitement) is expressed by voice, flight, and movement
at rest. Song, the chief signal of the possession of the territory, doubles
in its intensity at the approach of another bird. Sexual flight seems to be
of two sorts-one like a butterfly-slow flaps with full wings-the
other like a moth-rapid vibrations of partly opened wings (compare
the threatening flight of the Snow Bunting). Perching on a branch or the
ground, the male flutters one or both wings, or expands his tail. These
displays accompany attack on a territorial rival, but when the female is
at close quarters they are transferred into what a dancer might call the
"routines" of a chase that may end in successful or unsuccessful
mating. We cannot go very far wrong if we interpret his general reaction
as being one of threat (like the Snow Bunting) and his special reaction
battIe or courtship, depending whether, at close quarters, he finds a
female or another male.
Brightly colouredfemales-Some birds, like phalaropes and Button
Quails, have brightly coloured females and relatively dull-coloured
males. The roles of male and female in the life-cycle seem to be almost
completely reversed; when the female has laid the eggs it is the male
which has to sit on them. It is not surprising therefore to find that,
among these peculiar birds, the female takes the initiative in marking
out the territory, intimidates other females, and uses her bright colouration in male-like postures.
Bright colours in both sexes-If it is true (as we shall see later) that
the sexes are often recognised by their posture and movements, even
among some birds in which the sexes have different colours and
adornments, how much more true it be in the many cases where male
and female have almost identical plumage. In the breeding season the
male Goldcrest has a somewhat more fiery golden crest than the
female--otherwise they are outwardly identical. In an encounter
between rival males the crests are erected and used as the special
signalling organs of threat attitudes. They are used in courtship also, but
in this case the erection of the crest by the male evokes a different
response from the female. Much the same situation can be seen when
watching the use of their contrasting colouration by Great Tits or Blue

Disappearance and Defiance 123

Tits in sexual rivalry or courtship.
Robins, as David Lack mildly put it in his superb and intimate study
The Life a/the Robin, are "renowned for their pugnacity". Without any
doubt they are the most highly aggressive of any British bird. Intimidation is their daily life. Bright colours, with an entirely aggressive purpose, are found equally in both sexes and, except in part of their
breeding behaviour, so are intimidation and aggression. In autumn and
early winter both sexes hold territories which all except a few of the
females defend by song and by aggressive posturing. The male continues his territorial and aggressive activities practically throughout the
year, being joined in the spring often by a female from a neighbouring
territory, who then ceases to be a rival and becomes a mate, ceasing also
her songs and aggressive display.
Robins posture by stretching throat and breast to display the
maximum amount of red, and accompany this by swaying from side to
side. Colour, posture, and song are important. Robins will attack the
red breasts of whole stuffed adults (Plate 10), or just the red breast alone
stuck up on a piece of wire (in one case, after many attacks, a mount
was taken away and the robin continued to attack the place in the air
where it had been), or even a stuffed bird with the red of the breast
covered with brown ink; Robins also pursue other Robins (or even
other species of birds) when they see them fiying away; they also reply
to song by song, or to a distant view of another Robin by song. Their
mates alone, whom they recognise individually, are immune from this
sort of treatment.
Bright colours in both sexes in the breeding season-Many kinds of
birds have a seasonal change which is of the same nature in both sexes.
In winter the Black-headed Gull has a white head (with small dark
markings) and in summer a rich chocolate-brown one in both sexes (this
hood is never black). It seems that this donning of summer plumage in
both sexes is found very widely in social birds, like some gulls,
Guillemots, and Puffins; less often in non-social kinds.
In a Black-headed Gull colony both birds of the pair take a roughly
equal part in all the business of breeding, and both defend, by means of
threat, a small area round their nest. Hostility will be shown by a nesting
gull of either sex only when the territory is invaded-gulls will tolerate
each other in the neutral ground away from the nests. By using stuffed
birds we can find what it is in the intruder that causes the hostility (Fig.
37). A stuffed Black-headed Gull in full breeding plumage, if put in a


Watching Birds

37 Black -headed Gull attacking stuffed birds in winter (left) and summer
plumage (right)

territory, is vigorously attacked by the owners not only with their beaks
(with which they attack live intruding gulls), but also with their feet.
Normally, the Black-headed Gulls only attack human intruders with
their feet ---it can be imagined that the stuffed mount is the only sort of
invader likely to wait until the defender can get its feet into action.
Most of these attacks are directed against the "black" head of the
mount; clearly this adornment is important. We can find, by experiment, the limits of its importance. If we set up another stuffed gull, this
time in winter plumage-with a white, not chocolate, head-we see
that it is attacked almost as vigorously as the mount in full breeding
plumage. If we set up a corpse of a gull it will be attacked as long as its
pose bears some relation to that of a living bird. If we destroy the
corpse's realism by cutting off its head, for instance, it will no longer be
attacked, though the gulls may be apparently puzzled and frightened by it.

Disappearance and Defiance


So we have established that the black head is not all-important in

provoking intimidation, but that pose is important too. But the black
head seems to focus the display; and, even by itself, it can "release" the
aggressive display of the territory owner, provided it is in the right position. Set up on a skewer at normal height, the head of a decapitated bird
is attacked with beak and feet. Ifit falls to the ground, on the other hand,
it seems to be no longer capable of releasing aggressive behaviour; its
position is now more than that of an egg of an intruder. In fact,
sometimes when this happens the living bird may roll the head into its
nest and incubate it!

The complicated system of postures, movements, and the use of

colouration and song represented by aggressive display has a definite
biological purpose. It is of use. In their sexual rivalry, birds seldom fight
to the death; rather do they playa game of chess in which their territory
is often the chess-board, and their postures, colours and adornments the
pieces. The competitor or intruder nearly always "knows when he is
beaten" before feathers or even tempers are lost. Clearly this system is a
highly economical one--the loser is unhurt and free to carve out a
territory elsewhere, or to try his powers of bluff on a different male. The
species as a whole is prevented from suffering from the waste of its
precious individuals. As we will discuss in the next chapter, the
territorial system is of such usefulness and importance that birds as a
whole can afford this complicated (if not individually fatal) system of
sorting themselves out in the breeding season.
In certain kinds of birds it seems to be necessary to have additional
devices to avoid actual battle or after a display of intimidation. This is
particularly true of social birds. Among birds which normally live in
flocks, and particularly among those in which flocking extends into or
even through the breeding season, the normal releasing of sexual rivalry
might lead to serious complications were not some such system in
existence. Thus we find that Jackdaws, when threatened by others of
their kind, may turn and expose the least protected part of their
bodies-the backs of their necks. In the Jackdaw this is even specially
marked by a grey patch. When this submissive action is performed, the
aggressor is assured of moral victory, which in a sense is all he wants.
Submissive attitudes have been recorded in several other social birds


Watching Birds

(the Night Heron, for example), and, now that their importance is
realised, they are being found to exist quite widely in many sorts of
The importance of submission is shown in an interesting way by the
behaviour, in close confinement, of such male birds as do not submit.
(In nature these move off somewhere else after an exchange, which they
cannot do in captivity.) When several birds are confined together, one
soon becomes the despot, and when he is removed, another dictator
takes his place. In fact, such birds can be arranged in descending order,
according to which pecks which. Four male Blackbirds, which
Tinbergen kept in a small cage, "developed a severe despotism, as captive birds are apt to do in the spring, one of the males actually killing all
the others." This certainly would not have happened had Blackbirds
been naturally social birds, for then it is probable that some submissive
device would have been developed to prevent such mortal combats. It is
interesting to note that the domestic fowl, which in nature is not a social
bird, has, in the course of some thousands of generations of captivity,
developed a system by which it can hold a painless social hierarchy, and
that submissiveness plays a large part in preserving peace in the farmyard. That this does not always apply can, however be deduced from
the continued existence of fighting cocks.

8 How birds recognise one another

"I have now, past dispute, made out three distinct species of the willowwrens (Motacilla trochili) which constantly and invariably use distinct
notes. But at the same time I am obliged to confess that I know nothing
of your willow-lark. In my letter of 18 April, I had told you peremptorily
that I knew your willow-lark, but had not seen it then; but when I came
to procure it, it proved in all respects a very Motacilla trochilus, only
that it is a size larger than the other two, and the yellow-green of the
whole upper part of the body is more vivid, and the belly of a clearer
white. I have specimens of the three sorts now lying before me, and can
discern that there are three graduations of sizes and that the least has
black legs., and the other two flesh-coloured ones. The yellowist bird is
considerably the largest, and has its quill feathers and secondary
feathers tipped with white, which the others have not. This last haunts
only the tops of trees in high beechen woods, and makes a sibilous
grasshopper-like noise, now and then, at short intervals, shivering a little
with its wings when it sings, and is, I make no doubt now, the Regulus
non cristatus of Ray, which he says, 'cantat voce stridula locustae.' Yet
this great ornithologist never suspected that there were three species."
GILBERT WHITE, 17 August 1768
We must avoid placing ourselves in the birds' position when we deal
with the methods by which they recognise one another, whether others
of their own or the opposite sex, their parents or offspring, or their
species. We have no philosophical justification for imagining that,
because we recognise differences between a male and a female bird or
between two different sorts, the birds themselves recognise these
differences by the same characteristics. Only by a long process of objective observation, by taking nothing for granted, and often with the help
of actual experiments in the field, can we find out the real basis of
recognition in birds. It is becoming clear, as has already been hinted,
that in many cases postures and movements are just as important as, or
even more important than, special colouration in sex recpgnition.
The male Flicker (a kind of American woodpecker) is distinguishable
to man from the female, since the male possesses a handsome
"moustache" of black feathers on each side of his chin. Apparently a


128 Watching Birds

male Flicker can also distinguish a male from a female by this
characteristic, as has been proved by some recent field experiments. A
pair of birds had settled down to normal breeding behaviour, and were
clearly recognising each other by sight or habit or by posture and movement, or by a combination of these. The female was then provided with
a false moustache. When she was released the male approached her
from behind and began to mount her (the pair had reached this stage in
their breeding cycle). She turned round and he saw her moustache.
Immediately he went into his full "anti-male" aggressive display, pursuing the unfortunate female for two and a half hours and spreading his
tail to show the bright under-surface.
This experiment shows, first, that Flickers can recognise the sex of
other Flickers by posture, secondly, that the moustache, an adornment
perhaps, to human eyes, is also a recognition mark, thirdly, that the
contradiction artificially produced between male (moustache) and
female (posture) characters produces great excitability and a generally
anti-male reaction; and finally that the exhibition of the bright undersurface of the tail during the chase may be (in its colour and the way it is
shown) a further male-recognitional character.
In the Snow Bunting, Dr Tinbergen found that it was mainly the attitude and movements of the bird against which threat display was
directed that determined whether the threat should be continued as such
or transformed into courtship display. This explains some of the occasional cases of apparent homosexualism in birds. If, by some upset of
its sex-glands, or another cause, a male bird goes into a female attitude,
it will often be accepted as a female even though it may bear male
plumage-the displaying male may even try to mate with it. Among the
Ruffs and Reeves in the Waders' Aviary at the Zoo there are many
more males than females, and some of these often take up female attitudes. The consequent attempts at mating have often led onlookers to
suppose that Reeves also bear Ruffs.
Observers of the sexual behaviour of birds in the field have often (as
described in the case of the Black -headed Gull) used stuffed birds to test
reactions and recognition. In some cases this has been the means of discovering how the nature of a bird's sex is recognised by a rival or by a
possible mate. If a male Ruffed Grouse (an American bird) is presented
with the skin of a male of its own species stuffed in an ordinary attitude,
it will try to copulate with it-showing that in this particular case it is
the attitude, rather than the characters or adornments, that is important

7 Applying the ring, with special pliers, to a Common Sandpiper. For wading
birds, strong alloys are necessary to prevent the ring wearing out. (Photo: Jim
8 A special wedge-shaped nestbox for Treecreepers. (Photo: Jim Flegg)

9 The birdwatcher has great opportunities to experiment in tempting unusual

species into his nest boxes. Here, open-fronted boxes have been set at a sewage
disposal works to attract Pied Wagtails. (Photo: Jim Flegg)
10 A male Robin attacks the red breast of a stuffed bird hanging from a perch.
The Robin is one of the most aggressively territorial of British birds. (Photo:
Richard T. Mills)

11 By gently blowing aside the feathers, a ringer exposes the fleshy 'brood patch',
well supplied with blood vessels, with which the female Hawfinch (and other
species) warms her eggs during incubation. (Photo : Jim Flegg)
12 Ringed Plover about to settle on her pebble-shaped, pebble-coloured egg.
Note how the belly feathers are fluffed out so that the 'brood patch' will be in
contact with the eggs. (Photo : Richard T. Mills)

13 Bird rings of various sizes from several countries. Note how worn the tern
and petrel rings have become. (Photo : Jim Flegg)
14 Common Tern chicks, showing the camouflage pattern of their backs which
conceals them as they crouch, and the white 'bib' so conspicuous when they raise
their heads. (Photo: Jim Flegg)

How Birds Recognise one Another


in recognition-since the attitude in which a bird is normally stuffed is

essentially female, having, as Dr Tinbergen points out, the lack of movement and rather hunched position of a female willing to copulate.
The Blackcock does not show the same reactions to stuffed mounts
as does the Ruffed Grouse. This bird (in which the sexes are more widely different) always recognises the sex of the dummies; males attempt to
copulate with stuffed females, strike at stuffed males in the normal position, and, if a male is stuffed in the "rookooing" attitude, may strike
repeatedly at the adornments of the head. One bird eventually removed
the head and continued to strike at it where it lay three feet from the
We have now discussed two mechanisms, important in the recognition of the sexes--colour (and adornment) and posture. Male birds may
distinguish males from females by one or both of these characteristics.
There remains another important mechanism used for the purpose of
recognition-voice and song. Vocal sounds play their part in enabling
birds to recognise one another individually. Recognition, by birds, of individuals oftheir own species is a fact, though not a universal one. A lot
of work is being done on this subject; among recent discoveries are:
Black-headed Gulls and Song Sparrows recognise their neighbours, but
not strangers; paired Willets (an American wader) can recognise each
other without a display; gulls and penguins recognise and greet their
mates from afar; immature Night Herons (paired) recognise each other
after 20 days' separation, but not after 6 days if extra feathers are glued
to the head of one; young Night Herons do not recognise their parents,
but young Herring Gulls do, and their brothers and sisters as well; most
social birds recognise their own young. Gentoo Penguins recognise
their mates by crowing, though they sometimes make mistakes.
Song is a very important factor in enabling certain species which are
very similar in plumage, and which overlap in their breeding range, to
distinguish each other. In Britain we have two examples of pairs of
species which are almost indistinguishable in size, colour, and plumage:
the Chiffchaff and Willow Warbler, and the Marsh and Willow Tits.
Each pair of birds is very closely related, from the evidence of their
anatomical structure, and it can be imagined that it was not very long
since, in evolutionary perspective, that each pair shared a common
Without going into the arguments about how these species of birds
have come to have the same geographical distribution, we can examine


Watching Birds

the devices by which they are able to distinguish each other, and so keep
their identity as entirely different species. In both cases, warblers and
tits, the important mechanism seems to be song, or at least voice. The
difference between the "song" of the Chiffchaff (harsh and disyllabic)
and the trill of the Willow Warbler (sweet, plaintive note-Gilbert
White) is clear, so much so that it it is the chief character which enables
the human being, investigating the bird life of woodland, garden or
scrubland, to tell them apart. Though their habitats are not quite the
same-Chiffchaffs like older woodland with high song-posts, while
Willow Warblers seem to prefer open scrubland and can tolerate low
song-posts-there can be no doubt that the difference in song aids the
birds in avoiding a serious mistake in identification. The Wood Warbler,
it might also be said, is outwardly similar to those two, and also has a
very distinctive song (sibilous, shivering noise-Gilbert White).
Like these warblers, the Marsh and Willow Tits overlap in broad
geographical distribution, and a good deal in habitat. Although they are
superficially so much alike that ornithologists did not separate the
British species until 1900 (the chief anatomical difference between them
lies in the minute structure of the feathers of the head), yet they are able
to distinguish their own species, and thus avoid wasteful attempts to interbreed, by their call notes and songs. These are absolutely distinct.
The call notes of the Marsh Tit are four, which can be written,pitchuu
(the commonest), tsee-tsee-tsee, chick-a-bee-bee-bee, and a harsh note
chay. The last is the only one which is at all like the chay-chay-chay of
the Willow Tit, which in any case is much more harsh and twanging.
The Willow Tit never uses pitchuu, though it may make a sound chich in
its place, and its thin eez-eez-eez or high zi-zit are not found in the
Marsh Tit at all. The songs again are entirely different in the two
species-the piu-piu-piu of the Willow Tit is quite unlike the schuppi,
schip, or pitchaweco syllables of the Marsh Tit.
Practically all the finest songs of British birds are those in which the
sexes are alike (the Blackbird and the Blackcap are exceptions).
Though the main function of song in most perching birds must be
regarded as signalling the possession of a territory, we are prompted to
believe that the quality, extent, and varied nature of these songs also
form a mechanism by which the sexes recognise each other. With birds
such as Nightingales and warblers, it is reasonable to suppose that a
very distinctive song, in the absence of distinctive and recognisable
colour, is a great help to a female in finding a mate, and distinguishing

How Birds Recognise one Another


Hooded Crow
Area of overlap

Carrion Crow

38 Breeding ranges of Hooded Crow and Carrion Crow. showing area of



Watching Birds

him when he is founo.

Occasionally, in the course of evolution, a situation is produced in
which such distinguishing characters as have been developed are not
quite enough to keep the species entirely apart. Such a position exists
with regard to the Carrion and Hooded Crows. Derived originally from
a common ancestor, these birds have probably achieved, in the past,
complete geographical separation, and during the period in which they
lived apart they diverged from one another, one becoming (or staying)
black and the other developing its typical pied plumage. Later in time,
the Hooded Crow extended its bounds until once more it has come into
contact with its cousin, the Carrion Crow. In Britain the line of breeding
overlaps (Fig. 38), and extends from Ireland across the lowlands and
part of the highlands of Scotland. Here the two birds breed in the same
area, and, although for the most part they keep themselves to
themselves, a remarkable number of cases of interbreeding (with fertile
offspring, as far as can be seen) have been recorded. In the case of the
Crows, then, it is clear that an apparent, distinguishing characteristic is
not completely effective in preventing crossing. Recent experimental
work with Herring and Lesser Black-backed Gulls, where eggs have
been transferred from one species to the other, indicates that the chick
behaves as if it were the same species as its foster parents, and when
mature, will pair with that species despite obvious (to human eyes)
plumage differences between silver and slate-grey mantles.

9 Territory, courtship and

the breeding cycle
"During the amorous season, such a jealousy prevails between the male
birds that they can hardly bear to be together in the same hedge or field."
GILBERT WHITE, 8 February 1772

There are two modern definitions of bird territory which it will be well
to keep in mind. A general one {Tin bergen) is "whenever sexual fighting
is confined to a restricted area, that area is.a territory." A more special
one (Lack) describes a territory as an "isolated area defended by one individual of a species or by a breeding pair against intruders of the same
species and in which the owner of the territory makes itself
conspicuous. "
We must also bear in mind that the machinery of keeping a territory
is based on the aggressive colouration, adornment, song and action
which we have discussed in the last chapter. With this definition and
condition we can attempt to describe a bird's territorial life. The bird we
will select is imaginary, though there are many living birds like it; imaginary because no one species of bird shows all the typical attributes of
a territory-holder, and because it will be to our advantage to discuss the
rules before the exceptions, the type before the examples.
Our standard bird, then, is a land bird--a passerine (or perching
bird); it inhabits hedgerows, gardens, scrubland, or woodland; has a
brightly coloured male and a dull female; has a male which sings; is
partly migratory and partly resident; has catholic tastes in food; is, on
the whole, monogamous. In winter mixed flocks of males and females
work the hedgerows, fields, gardens, wood-edges, rickyards, or beaches
above high-water mark of some country or countries in the Holarctic
Region-temperate Europe, Asia, or North America.
At the end of the winter-perhaps in early March-these flocks
cease to be the entirely amicable affairs they have been since autumn.
They still retain their function-that of co-operative food finding, so
that the discovery of one is shared by the others-but quarrels, not over


Watching Birds

food so far as can be seen, nor over anything tangible, begin to break
out between males. They may flirt their wings or posture at one another,
and have little fruitless chases-nothing serious, but enough to show
that some internal change is taking place in the males' make-up that
prevents them, temporarily, from behaving like ordinary members of
the flock.
As time goes on these quarrels tend to become slightly more serious
and more prolonged, and are accompanied by little expositions of the
breeding song, but before they become really acute the males begin to
go away for short periods instead. They pay visits to suitable small
areas of their summer breeding habitat. At first these visits are very
short, and involve the prospecting of a fairly wide area of the summer
habitat; as time goes on the period spent away from the flock grows
longer and longer, and the area visited smaller and smaller, until a day
comes (or a night rather) when the male has left the flock altogether and
sleeps in what is now the "rough copy" of his breeding territory.
By now he is well acquainted with his home. The boundaries of it interest him little as yet; most of his business concerns several points of
vantage, to which he continually hops or flies, and from which he sings
first a few quiet bars, or a little shadowy copy of what, in a day or two,
he will be pouring forth with all his might as his full spring song. The
paths to his songposts become as clear to him as the route from garden
gate to back door is to us. The post or gate or branch from which he
sings is approached perhaps by a flight to a bush, another to a branch, a
hop to the left, a quick flight to the right, and a hop straight upwards: he
seldom departs from this routine.
As time goes on he visits his headquarters more often, and may sing
for as much as an hour on end; he seems to favour one or two strategic
songposts more and more, so he cuts the number down, though, when
passing the immediate neighbourhood of one that he has discarded, he
may still go through his stereotyped routine of path-movement. With
the increase of his song and preoccupation with headquarters he goes
less far afield for foraging, until he is feeding entirely in the loosely
defined area he owns.
This area does not stay loosely defined for long. Other males of the
same species, who have also left the flocks, approach, fly past, sing, and
come foraging in his area. He is not tolerant of these birds. He chases
them, postures aggressively, and sings at them. Soon he finds that certain of these birds are his neighbours, staking claims on the other side of

Territory, Courtship and the Breeding cycle


the garden, on a branch of the next big tree, or fifty yards down the
hedge. His aggressive reactions towards them are more patterned; he
plays them at song-tennis over the neutral ground between-ground
which rapidly becomes less and less neutral. When one of his
neighbours, that are now his rivals, alights in his area, he makes a
display flight at it, often singing on the wing; the neighbour retreats into
his own area, and ifhe is followed, the roles are reversed. In such a way
the boundaries of the territories are marked out. Eventually it becomes
possible for the human observer to plot the borders ofthe territories on
a map, almost down to the last blade of grass. Over these borders are
fought the most bitter battles-here there is least to distinguish the
rivals in pugnacity. For our birds recognise the aggressor, and the
further a fight ranges into the home bird's territory, the more aggressive
does he become, and the less aggressive his rival; only on the borders
are they equally matched-in fact, the border is where they are equally
When our male first became resident in his territory, he owned about
two acres. His battles with his neighbours have cut the area down to
one; he may now be in relation to four or more other males on different
sides, each with about an acre, too. It will be perhaps about three weeks
since he left the flock.
It is now the females' turn to leave the flock. They seem to forage individually farther and farther afield; one passes through a male's
territory and is threatened as ifshe was a male; hertimeis not quite ripe,
for she takes no notice of his song and goes on her way. The next one
that arrives has been attracted by the male's song-she lands in the
territory and approaches. The male greets her in exactly the same way
as he would a rival male entering his territory-by threat. Not until she
is at close quarters does he recognise her and change his attitude. Then
comes a sexual chase. Round and round the territory the two birds fly,
the male trying to grasp thc female's back, bring her to the ground, and
mate with her. Eventually he gives up, and both land, the male often
finishing with a little courtship display, and often a call that seems to
represent frustration. For, though the male is ready to copulate, the
female is not, and may not be for some days or even weeks-although
she was ready to be attracted into the territory in the first place.
Sexual chases now become established as a sort of daily routine, and
though they indicate that successful copulation has not yet taken place,
they show all the same (as Dr Tinbergen points out) that the birds are


Watching Birds

paired. Though the female will not allow the male to copulate with her,
she docs not leave him. Apart from their frequent sexual flights, the
birds learn to recognise each other individually, thus dispensing more
and more with the usual recognitional displays. The female helps the
male to protect the territory (and his aggressive attitude to his
neighbours increases still more), not by attacking his rival males, but by
attacking other females.
At this stage the male's aggressive behaviour is still increasing, and is
strongest towards the centre or headquarters of the territory, and less
strong towards the borders. Even now, when neighbouring males are
mated, and consequently more pugnacious, a new male, late from the
flock, may (no doubt encouraged by the absence of song) try to stake
out a territory between those already occupied. Sometimes he may
succeed, depending on the distance between his chosen headquarters
and that of the birds already in possession, for up to a certain minimum
limit territories are compressible. If he does not transgress this limit, he
may succeed; if he does, he gives up the struggle and moves on.
One day the female shows great interest in one or two bushes, or a
stretch of hedge. She picks up a scrap of nest material. The male approaches her, and this time the normal sexual chase does notfollow. She
is ripe for copulation, the state of her breeding organs has crossed a certain threshold; with flattened back and lifted tail she invites the male,
and he mounts and copulates with her. But even now this does not
always happen-she may invite, but the male may not be receptive, and
then she will relinquish her attitude; the male may invite, and another
sexual chase take place; copulation may be unsuccessful, and may
result in courtship posturing. Rapidly, however, the birds become used
to one another, and the female starts building the nest in earnest. The
male too shows signs of building activity; he may pass building material
to the female, may add it to the nest himself, or may make feeble and unfinished "cock-nests" of his own. From a week to a fortnight after the
first copulation the nest is complete.
The female now becomes restless, and makes frequent visits to the
nest. One morning, early, she visits it for over half an hour; she does this
again the next day and the next and the next. Four eggs are there when
we look, though during those four days oflaying the nest was still being
lined with feathers. The female no longer allows the male to copulate;
for his part he resumes his song, which is almost as strong as if he was
unmated, though he has been relatively quiet since she arrived in his

Territory, Courtship and the Breeding cycle


territory. A day or two after she has laid the fourth egg she begins to sit.
The male takes no part in the incubation, but continues his territorial
song and aggressiveness in the intervals of foraging for himself and
taking food to the female on the nest.
After a fortnight the eggs hatch. The young are like those of most
passerine birds, at first almost naked and blind. The business of feeding
them occupies the parents almost the whole of their time. For a day or
two the young are fed from the crop; after this large quantities of insects
are needed and are brought to the nest three or four times an hour. As
the nestlings grow larger and hungrier, every hour of daylight means
five or six, then eight or nine, then twelve, and, towards the end, sixteen
visits. To collect these insects the parents have to forage wherever insects are, and parties of parents will hunt together in neutral ground or
even over part of the territory of one of the pairs, and even in the latter
case little aggressive behaviour will be aroused. Every day the young
grow noisier and more active. A fortnight after hatching their excrement
is no longer voided in a little gelatinous bag which can be removed by
their parents, but is deposited instead on the rim of the nest (a sign, by
the way, of a successful nest if you come across it later in the season).
There is no longer need to avoid fouling the nest; though they cannot fly
properly they have left it. They hide now, a special call signalling their
presence to their parents. Sometimes the parents each take charge of
half the fledglings. After a week or ten days the young begin to feed
themselves, after another week they are no longer fed by their parents at
all, in another day or two their parent-calls have been replaced by the
ordinary adult flocking-call, and they are off on their own.
Long before they finally go altogether the young have been
wandering more or less where they would. Even when fed by their
parents they have trespassed into neighbouring territories where they,
and often their parents too, have been tolerated. But when they are finally independent their parents are found to be defending their own
territory again; the male, who was too busy to sing while he was feeding
the young is in full song, the female refusing copulation until she is ripe
for the recurrence of her cycle that means a second brood. And after the
whole process has been gone through again with the second brood, the
parents (unless indeed they have a third or fourth) will lose their urge to
copulate (an urge which, we have seen, is oflonger and steadier duration
in the male than in the female). Moult will have started-the old (and by
now very worn) feathers falling out in strict sequence over perhaps two


Watching Birds
months, and being replaced by fresh new ones with good insulating
power to stave off winter's chill night winds. The birds will lose their
territorial sense; flock communication sounds will replace male song;
and, like their young, they will wander off foraging and the autumn flock
will be established again.
The composite bird which we have described in such detail owes
much to the buntings and to those who have so carefully studied them.
Now we have a picture of the life of a territorial bird, and we can compare the lives of real birds with this picture. We have traced the breeding
history of our standard bird stage by stage from the moment when the
winter flocks break up until the moment when the autumn birds show
signs of flocking again. On our way we have passed several milestones;
let us take the journey again now, resting for a time at each milestone,
and see what the different sorts of birds are really doing.

Territories can be taken up by males (the most usual case, as with our
example), by both sexes together (particularly among seabirds and
some arctic waders that pair up on migration, before they have arrived
at their breeding place), or by females (for instance, phalaropes and Button Quails, where the female has the bright colours and the aggressive
display). To take up the territories, if they are a migratory species, the
males (we shall exclude the other cases) leave first for the north ahead of
the females; or stay more or less where they are, if they are resident or
hold winter territories. Birds which do the latter deserve rather a special
mention. If we look back to page 133 we see thatTinbergen's definition
of a territory hints at a sexual purpose, while that of Lack (who extensively studied the Robin, which holds a winter territory) carefully avoids
doing this. If we look-from an evolutionary point of view-at the
business of winter territory, in which males and females which were
mates in the summer may be rivals in the autumn, we can see that these
two definitions may not be contradictory, provided, as seems likely, one
habit has evolved out of the other. It is possible to imagine that the
keeping of winter territory by such species as practise it may, in the
course of evolution, have been an extension or resumption of the normal
breeding-cycle territory, and that though originally a purely sexual
affair, it now serves in winter for other purposes. For instance, it keeps
the species evenly spread in regions of scanty food, but of course the

Territory. Courtship and the Breeding cycle


effectiveness of this depends on the kind of food requirement. Many

invertebrate-eating birds derive advantage in winter flocking, since a
group or swarm of hibernating creatures turned up by one bird becomes
the prey of all.
Winter territory persists, to a small extent, in quite a number of birds.
Those in whose lives it plays an important part range from California
shrikes and Mocking Birds to San Francisco Spotted Towhees; in Britain the male Blackbird holds a winter territory to a certain extent; and
some females hold them also. The finest example in Britain, though, is
the Robin.

Mid-October 193e

Mid-April 1937

Mid-October 1937

Mid-April 1938

39 A two-year history of Robin territories (after David Lack}-Ietters,

roman or greek, represent individual birds; circles indicate occupied territories
whose boundaries are the dotted lines. An individual's territory and the history
of its mating can be traced on the sequence of maps


Watching Birds

A Robin may inhabit only a few acres during the whole of its life,
though certain females wander, and a few are even migratory. In winter
(contrary to the impression given by some Christmas cards) both male
and female hold individual territories, which together are almost exactly
the size of their summer ones. These they defend, like most aggressive
birds, by song and dance. In late winter or spring the females cease their
territorial activity, and may often mate with a neighbouring male rival,
sometimes the same mate in successive years (Fig. 39). Only in early
autumn, after the waning of breeding activity, is there a time-gap in
which territorial activity is low.
There is only one bird known to be more highly resident than the
Robin-the Wrentit, an American species belonging to a family of
birds not occurring in the British Isles. A male Wrentit takes up a
territory in the first March after he has fledged, and keeps it all the year
round for the rest of his life. He stakes it out and keeps it by song and
fight, and when a female joins him she helps in the fighting. If the female
dies, the male waits for a new one; ifthe male dies, the female deserts the
territory for, or fuses it with, that of an unmated male. Such territories
as fall vacant are taken by males (mainly young) that have none.
It appears that both our definitions of territory (p. 133) work in the
case of the Wrentit. To judge from their behaviour, sexual activity in the
pair never falls below a stage equivalent to the period of sexual chases in
our standard bird-that is, the male and female are bound by a sexual
bond throughout the year, though they only reach the stage where the
female will accept copulation at breeding time. This behaviour might
seem ordinary to a student of monkeys or man, but is quite remarkable
among birds.

Practically all territorial birds use song, chasing, and fighting in the
defence of their plot of ground. In the buntings (which include the
American "sparrows"), behaviour (see Fig. 36) in defence of the area
(see Fig. 40) is almost identical with that of our standard bird. The key
to claim-staking is exhibitionism; birds make it obvious to others that
they are in possession. Hence species with weak songs, Stonechats, for
example, have a headquarters where they stand in full view and show
their contrasting plumage; at the opposite extreme, Nightingales, which
make no appeal to sight, have a correspondingly loud song.

Territory, Courtship and the Breeding cycle


40 Reed Bunting territories on the River Isis between The Trout and King's
Weir. Nine male bird territories have been plotted from observation of song
posts. Note the even spread of territories, conditioned, even so, by the supply of
sprigs and bushes to serve as song post along the three-quarter of a mile stretch
of river


Watching Birds

Actual fighting is replaced by bluff and other "substitute ceremonies"

in many species, particularly social ones, where fighting would be an
expensive and useless luxury. Thus Herring Gulls do not fight, but symbolically pluck grass, and Black-headed Gulls seldom fight with an immediate neighbour in their colony, but only seriously with strange birds
not known to them.
Provided they can recognise them as such, territorial birds do not as a
rule attack birds of species other than their own. Although Snow Buntings have the same threat reaction to males and females of their own
species when some way away, and thus may not distinguish between
them at a distance (although their plumage seems very different to us),
yet they can distinguish their own kind from Lapland Buntings or
Wheatears, which often share the same breeding-ground. They have
never been seen to threaten these other species. Though these other
birds are to a certain extent competing for the same food, they are not
sexual competitors, and to a breeding Snow Bunting it is sex that
In the same way breeding Willow Warblers and Nightjars threaten
their own species (i.e. sexual competitors), but not others which eat the
same food. Nuthatches, however, display to and attack birds of such
other species as are competing for nest-sites, like tits and Starlings; but
these battles are against birds which might interfere with their breedingcycle, not their food supply.
Swans will chase any large animal form their territory; although
Ringed Plovers will chase Skylarks and Linnets, Little Ringed Plovers
(a smaller species) will even try to chase sheep. We can perhaps explain
this by pointing out that these birds are guarding the nest; Ringed
Plovers, with their nest on the ground, have it exposed to the danger of
being trodden on by mistake as well as deliberately -raided-not that
this explains their attitude to Larks and Linnets.
We can thus reach the general conclusion that birds normally attack
other species in their territory only when those animals tend to interfere
with the breedingcycle.

The normal, average size of bird territories is greatly variable. For

non-colonial and easily studied species (David Lack's Robins or David
Snow's Blackbirds) this often appears to be between a half and one-and-

Territory. Court.ship and the Breeding cycle


41 Partridge territories on Suffolk farmland in 1964 and 1965 from CBC

reports, showing decline in territories due to changes in agricultural practice
and use of pesticides, with consequent reduction in insect food for the birds


Watching Birds

a-half acres. However, Kenneth Williamson, looking at Wrens on

farmland, found that whilst the size (and shape) of territories depended
on the nature of the habitat (i.e. territories were more or less circular in
woods, but very elongated in hedgerows), the temporary reduction in
Wren numbers and subsequent rapid increase following the severe 1963
winter made little difference to the size of territory occupied. What
happened was that when all the available "first-choice" habitat
(woodland for the Wren) had been filled, then territories began to be
taken up in "secondary" habitat like hedgerows, and in this poorer
ground they were larger and held in less stable tenure (Figs. 41-43).

42 Wren territories in Suffolk, 1964 and 1967, from eBe reports, showing
recovery of the species after its heavy losses in the severe winter of 1962/63

Territory, Courtship and the Breeding cycle

43 Whitethroat territories in Suffolk 1968 and 1969, from

showing results of population "crash" between the seasons




Clearly, for colonial birds (the gulls, or Gannets, for example) only
the immediate vicinity of the nest is protected, and this is true for some
of the ducks, which may also have a second, separate, "territory" on
their main feeding water.

Our standard bird had a few very definite songposts in his territory,
from which he sang and displayed. As time went on he reduced the
number of these, showing a clear preference for one or two. This is not
always so. Some of the American warblers never have definite
songposts, but sing from anywhere within the territory. The Rosy Finch
seems to use not a bush, a branch, or a bank, but his own female. The
Broad-tailed Humming-bird may have as many as eleven flight-posts in
his small territory. Naturally, birds like the Skylark (which may
sometimes sing from the ground or from a fence post) spend most of
their song time in mid-air, over their territory but at various altitudes
and positions.
The nest lay within the territory of our standard bird. Even with buntings, which approach the standard very closely, it may not do so. One
of the female Snow Buntings watched by Dr Tinbergen built her nest


Watching Birds

some distance outside the male's territory. By dint of a two-day

"battle" with the neighbour, he conquered the ground near the nest.
Other buntings (like Bachman's Sparrow in America), and even
warblers such as Chiffchaffs, may sometimes build nests outside the
territory, as much as 100 to 150 yards from the territorial headquarters.
African Bishop-birds, which are polygamous, have three or four wives,
and the nests of one or more may occasionally be outside the territory,
Much discussion and controversy has taken place as to the biological
value of territory. In particular, the relation between territory and food
supply has occupied many pages of print in the learned journals.
Howard was the first to suggest that the system of territory holding
might confer advantages on birds by assuring a regular food supply.
Some critics have maintained that because birds did not always seek
food in their territories, this was not so. It will be remembered that our
standard bird sought food for its young outside its territory; as far as I
know there is no single case yet published of any species of bird which is
never known to seek food outside its territory, during such time as it
holds one. Warblers, buntings, and Dabchicks seek food mostly in their
territories. American Robins and Purple Sandpipers feed in them, but
also at a common feeding-ground where they do not attack neighbours.
Common feeding-grounds are used by Lapwings, Great Crested
Grebes, and many other social birds, and in very few farmland or
woodland areas (where most birds are strongly territorial) does each
territory have a regular and reliable pool for drinking and bathing.
These facilities, although sometimes lying within a territory, seem to be
approached and used without an aggressive response--it would be
extremely interesting to know how this is achieved.
It is clear, then, that the possession of a half-acre territory by a nonsocial bird confers a general advantage rather than a special one concerning the food available in the territory itself. If the latter were the case,
we might expect that food-competitors of other species would not be
tolerated; the evidence goes to show that they are. The general advantage lies in the fact that territory ensures an even distribution of birds
over an area, thus not stretching unduly the limits of food supply in any
one place while neglecting sources of food in another.

True courtship, as distinct from aggressive display, is found among

Territory. Courtship and the Breeding cycle


all sorts of birds, territorial and otherwise. The reader is particularly

referred to the pictures of courtship and aggressive display in Fig. 36.
The object of courtship seems to be to strengthen the bonds between
male and female, ensuring that they go through the successive phases of
their cycle in away, and at a time, suitable to one another, and, more especially, to act as a preliminary to copulation. Courtship may take the
forms of vocal demonstration (grebes and divers), sexual flights and
chases (buntings, see Fig. 36), and various ceremonies derived and
extended from the ordinary details of daily life, such as the feeding of the
female by the male (Robins, gulls, and parrots), "false drinking"
(Gannets and Smews), false preening, wing-lifting (Common and Purple Sandpipers), short leap-frog flights (Green Sandpipers), or the
presentation or exchange of nest material. Whilst the water dances of
the grebes, and the courtship feeding of Robins and Blue Tits, are
evidently essential to the pairing process and satisfying to human
observers, we must not let our emotional viewpoint blind us to the
possibly rather prosaic explanations. It seems very likely that courtshipfeeding, for example, is valuable if the female is to achieve the right condition for egg production, and to begin the breeding season as promptly
as possible. A glance at Fig. 44 shows just how much weight the female
Blue Tit must put on (in terms of gonad development and the stored
food to provide the nutriment within the egg) and how quickly. This
becomes much easier if both birds participate in finding her food!

E 12

:: 10















44 Weights of male and female Blue Tits throughout the year, showing spectacular weight increase in female before egg laying (from the book
Birdwatchers' Year)

After the period of sexual flights and preliminary courtship is over,

the stage of su~cessful copulation is reached. The act may take place on


Watching Birds
























45 Weights of two resident species (Robin and Dunnock) and two migrant
species (Blackcap and Whitethroat) plotted to show weight increases (fat
reserves) of resident birds before the onset of winter, and before migration

land, on water (swans, ducks), or in the air (Swifts), and may follow no
apparent ceremony (divers and some terns), or a special courtship display (most birds). In some birds the male may invite the female (gulls,
woodpeckers, penguins), in others the female may invite the male (many
ducks), either may invite either (Common Terns), or it may be difficult
to decide which takes the initiative (buntings). Copulation may continue
until the first egg is laid (some buntings), until incubation begins (other
buntings, Herring Gulls, Skimmers), or during incubation and even
after the eggs hatch (Black-headed Gulls, Common Terns).
Detailed descriptions of the courtships of all sorts of birds are now
common in bird literature, so much so that the editors of the standard
work on British birds (Witherby's The Handbook o/British Birds) have
managed to include a description, in many cases very detailed, of the
courtship of every important bird on the British list. This book does not
attempt to be a handbook so much as a guide, so there is no reason why
the reader should be plagued with what has been more adequately
described elsewhere. But though we must leave the appreciation of the
individual details of the male-female courtship (as opposed to male-

Territory. Courtship and the Breeding cycle


male intimidation) of our British birds to students of the Handbook-and the more students it has the better-we cannot leave the
subject altogether without giving some examples of how courtship has
inspired moving description in bird literature. Here are three such
David Lack. scientist. on the Robin: "The first copulation and the
first 'courtship-feeding' occur within a day of each other, but the two are
quite separate from each other. The female invites the male to feed her
with the same attitude with vigorously quivered wings and loud call as
that in which the fledgling begs for food; the male comes with food in his
beak and passes it to her, the female swallows it. When the performance
starts in late March, the male may just hop up to the female and put
food in her mouth whilst she barely quivers the wings or calls, but, after
a day or two, both birds are much more excited, the female begging and
being fed persistently."

Julian Huxley. scientist. with artistic approach. on the Redshank: "I

spent some time watching them, and soon saw the redshanks courting.
It was one of the most entrancing of spectacles. Redshanks, cock as well
as hen, are sober-coloured enough as you see their trim brown bodies
slipping through the herbage. But during the courtship all is changed.
The cock-bird advances towards the hen with his graceful pointed wings
raised above his back, showing their pure-white under-surface. He lifts
his scarlet legs alternately in a deliberate way-a sort of graceful goosestep--and utters all the while a clear, far-carrying trill, full of wildness,
charged with desire, piercing, and exciting. Sometimes, as he nears the
hen, he begins to fan his wings a littie, just lifting himself off the ground,
so that he is walking on air. The hen will often suffer his approach till he
is quite close, then shy away like a startled horse, and begin running,
upon which he folds his wings and runs after. She generally runs in
circles, as if the pursuit were not wholly disagreeable to her, and so they
turn and loop over the gleaming mud. Then she pauses again, and the
tremulous approach is again enacted."

Edmund Selous, artist. with scientific approach, on the Stock Dove:

"However it may be, the bow itself-which I will now notice more
fully-is certainly of a nuptial character, and is seen in its greatest
perfection only when the male Stock Dove courts the female. This he
does by either flying or walking up to her and bowing solemnly till his


Watching Birds

breast touches the ground, his tail going up at the same time to an even
more than corresponding height, though with an action less solemn. The
tail in its ascent is beautifully fanned, but it is not spread out like a fan,
but arched, which adds to the beauty of its appearance. As it is brought
down it closes again, but, should the bow be followed up, it is instantly
again fanned out and sweeps the ground, as its owner, now risen from
his prostrate attitude, with head erect and throat swelled, makes a little
rush towards the object of his desires. The preliminary bow, however, is
more usually followed by another, or by two or three others, each one
being a distinct and separate affair, the bird remaining with his head
sunk and tail raised and fanned for some seconds before rising to repeat.
Thus it is not like two or three little bobs-which is the manner of
wooing pursued by the Turtle Dove--but there is one set bow, to which
but one elevation and depression of the tail belongs, and the offerer of it
must not only regain his normal upright attitude, but remain in it for a
perceptible period before making another. This bow, therefore, is of the
most impressive and even solemn nature, and expresses, as much as
anything in dumb show can express, 'Madam, I am your most
devoted.' "

10 What you can do

"I partly engaged that I would sometime do myself the honour to write
to you on the subject of natural history; and 1am the more ready to fulfil
my promise, because 1 see you are a gentleman of great candour, and
one that will make allowances; especially where the writer professes to
be an out-door naturalist, one that takes his observations from the subject itself, and not from the writings of others."

30 June 1769

This book is about birds, birdwatching and birdwatchers. It is designed

to give the reader some insight into the lives of birds and to indicate
some of the fascinating realms that will open if he pursues his hobby
further. Just as in learning how to distinguish one bird species from
another, or how to separate the two sexes, experience is the greatest
teacher, and one of birds' most welcome attractions is that they are
always close to you. Wherever you are, there will almost certainly be
birds and consequently, for the birdwatcher, an inexhaustible source of
interest, wonderment and satisfaction. In Africa, for example, it will be
the number of species that is bewildering; in central London, by contrast, the aerobatic problems facing the huge wheeling flocks of
Starlings as they come in to roost in the fading light on a winter evening.
Birds can usefully be watched, counted and compared in the different
types of countryside passed through on a long train journey (which is
really a form of transect); or every day on a short commuting trip
(which is a form of census). You are more likely to see Kestrels on a car
journey by motorway than elsewhere (because the long grass of the
verges is ideal for hunting voles), though sadly you cannot take the opportunity to study them closely while they hover!
Implicit in this is the idea that bird watching should never be a case of
"Oh, there was only a Blue Tit". Naturally, individual birdwatchers will
differ in their approach, some using binoculars the better to appreciate
the Kingfisher-nature of the Blue Tit's crown, others to see just where it
is feeding, or how it tackles a peanut. Never, never make the quite common mistake that assumes that, once you take an interest in bird
biology or numbers, you are mysteriously prohibited from appreciating



Watching Birds

and enjoying the beauty and charm of these creatures. On the contrary,
the more you find out, the more you enquire, the greater the fascination.
Birdwatching can be, if you wish, a completely solo pursuit. Many
books are available to guide you if you prefer to teach yourself. Equally,
perhaps even better, it can be a co-operative enterprise. Whilst one or
two is the ideal number if the watcher wants really good views, properly
organised group outings can be immensely helpful to the beginner, not
only by providing expert help with field identification, but also in
showing you the best local birding spots. So, if you are starting out to investigate birdwatching, first find your local society. These are now very
numerous-far too numerous to list. Almost all counties have a County
Society, while most large towns either have their own club or an RSPB
"members' group", and this is true of a good many villages. Often your
local library will be able to give you useful addresses, but in cases of
difficulty The Council for Nature (c/o Zoological Gardens, Regent's
Park, London, NWl) which serves as the co-ordinating body for
Natural History Societies, should be able to help.
Clubs and societies like these often run a series of field meetings
during the year to places of interest, sometimes a day's coach trip away,
and during the winter have a series of indoor meetings with a wide variety of films and speakers-there should be enough to cater for most
tastes. If your birdwatching leanings are a little more academic, many
Workers' Educational Associations (in the Telephone Directory)
organise various courses, some for beginners, some for more advanced
students, at many centres, one of which is likely to be quite near your
home. As with all hobbies, practice helps immensely. It is really surprising how many birdwatchers fail to get the best out of their
binoculars for this reason, and are slow at picking up and focusing on a
flying bird, or one jumping about in a bush, merely because this doesn't
come as second nature-but, given practice, it will.
All the bird books in the world cannot teach you to identify birds
quickly if you have no field experience. With birds, there are many little
things, difficult to put down in words (and often different for each of us)
that make a bird obviously what it is-"jizz" again. It may be a springy,
buoyant way of flying, or an oddly upright perching position-but
once, through field experience, you are familiar with it, it "clicks" instantly in your mind. If you want a real demonstration, try now to
decide how you know that a female House Sparrow is just that, or jot
down in detail the plumage characteristics of a Meadow Pipit.

What You Can Do


Clearly you should never be without notebook and pencil, and if you
can sketch roughly what you see, so much the better. In the early days,
take your binoculars, your field identification guide, and your notebook
to as many different habitats as possible. Get to know the regular birds
that you can expect at different times of year, and better still, get to
know their habits. Which species are confiding, like Treecreepers, and
allow a close approach? Which are just the opposite, like Redshanks or
Blackbirds, and go shrieking off, alarming everything else before you
have had a proper look around? All these facets, put together, help you
to achieve a closer contact, and thus more enjoyment, with birds.
You will soon find that low tide on the coast, or in an estuary, is no
time for good views of ducks or waders-where, then, are they forced to
concentrate when the tide comes in? Follow the flightlines and see for
yourself. In wetland areas, particularly, when is the sun going to be
shining in your eyes? This is a time best avoided, of course, unless you
fancy identifying silhouettes!
Remember courtesy while you do all this. There may be other
birdwatchers around (even if you haven't noticed them), so, having seen
as much as you want, don't just stand up and walk off-leave as inconspicuously and as quietly as you came. Even more important,
always put the birds first. Never harass tired migrants or unusual birds
for just that bit of a better view, and never take risks with nests, even if
they are of very common species. If you are a photographer, the same
rules apply-perhaps even more strictly at the nest. If you cannot take
a photograph without disturbing the vegetation, don't take it!
Remember, and observe, the Protection of Birds Acts.
This, really, is part and parcel of ensuring that there will be birds
around for your grandchildren to enjoy. Conservation is this, and more.
Even within your garden, by putting out food and especially water, by
planting trees and shrubs (nothing has a lower bird density than plain,
mown, grass) and by putting up nestboxes, you can do your bit.
As taxpayers, we also do a bit towards conservation-but a very
small bit it is. Our Government, through the Nature Conservancy Council, does purchase and maintain some reserves, but the money
budgetted for this task is pitifully small and can only be described as
woefully inadequate. It is strange that our elected representatives
should feel this way about our environment, for the voluntary, or
charitable, bodies that own and maintain nature reserves have wide
public support. Which is just as well, because they must shoulder the


Watching Birds

bulk of the burden. A thousand-acre nature reserve costs very much less
than a single jet fighter plane!
Three major voluntary bodies share this duty. The National Trust
(42 Queen Anne's Gate, London, SWl) has, as well as its better-known
stately homes,large areas of our countryside and coast under its protection, some as nature reserves. The Wildfowl Trust (Slimbridge,
Gloucestershire) has a number of wildfowl refuges in various parts of
Britain and, incidentally, keeps collections of wildfowl from all over the
world (these, and the wild birds, are well worth seeing for their own sake
and in order to become familiar with this group). The Royal Society for
the Protection of Birds (The Lodge, Sandy, Bedfordshire) also maintains and wardens reserves in all types of habitat in Britain and
Northern Ireland. Besides acting as the birdwatchers' "watchdog" in
protecting rare breeding birds, such as Ospreys and Avocets, and in
helping to ensure that the Bird Protection Acts are enforced (particularly where the taking of eggs or wild birds for caging is concerned), the
RSPB is our most powerful lobby, being by far the biggest of the
birdwatchers' societies. Members have privileges in visiting reserves,
and the Society has a range of film, educational and other services
available, as well as a strong and well-organised junior wing, the Young
Ornithologists' Club.
On a more local level, most counties now have a County Naturalists'
Trust, which owns and maintains a variety of reserves, some for plants
especially, some for birds, and so on. Your library should be able to tell
you the address of the County Secretary, but if not, the County Trusts'
parent body, The Societyfor the Promotion ofNature Reserves (Alford
Manor House, Alford, Lincolnshire) certainly will.
With pressures increasing at the present rate, not only on our birds,
but on our whole environment, it is now possible to argue that
membership of bodies like the RSPB and your County Trust has
become a duty that none of us should shirk-after all, we share that environment with the wildlife.
There remains one other way in which you can help-to join in and
share the enjoyments of co-operative studies, and in one sense this is
what all the editions of this book have encouraged birdwatchers to do.
The accumulation of biological facts about birds can be completely
fascinating and absorbing-and we have seen that it should add to your
enjoyment of birdwatching. Just as nature reserves are so necessary
today-areas where "progress" can be realistically and sensibly

What You Can Do


managed-so too are facts and figures concerning our birds. Without
them, how can we arrive at sensible environmental management plans,
how can we argue for nationwide (or worldwide) conservation
measures, like the control of pollution, restraint in pesticide usage,
rational usage of natural resources like land? While this edition is being
written, the Western World is in the throes of an energy crisis the like of
which we have not seen before. As I write, it seems most probable that a
temporary solution will be sought in extracting more fossil fuels from
technically difficult and environmentally dangerous areas (out of sight
does not imply safety), like the North Sea or even the western Atlantic,
and this as fast as possible. Re-cycling of energy or raw materials barely
receives a mention. Housing and industrial development show much the
same gloomy picture-everywhere, even in remotest Scotland,
piecemeal development occurs more or less unchecked. No thought is
given to an overall, national strategy which is so desperately needed. Of
course man must continue to live in comfort and to be fed, but
ecologists are concerned at the ultimate cost if we neglect plans for the
future in our anxiety to provide instant remedies for the immediate
This may seem very sombre, and a situation far removed from any
assistance that a birdwatcher can give-but this need not be so. We are
discussing the quality of our life, our environment, and as birdwatchers
the natural aspects of that environment are even more important. Who
better than ourselves to defend this quality, or improve it? Certainly it
cannot improve if we shrug our shoulders and turn away-and why
should we, anyway, if we enjoy our birdwatching. We can co-operate
with others without in any way spoiling our enjoyment-on the
As an individual, you may make lists of the birds you see, carry out
regular counts of a certain area, feed the birds in your garden, put up
nestboxes and see how many young are reared and how they fare. The
British Trust/or Ornithology (Beech Grove, Tring, Hertfordshire) was
founded by birdwatchers who foresaw the value, practicability and
enjoyment-potential of co-operation in field studies, and any active
birdwatcher should encourage his local club to participate, and, of
course, should involve himself. At anyone time, the BTO has a number
of projects running: some are organised from headquarters, others by
individuals or groups of members. Standards vary, both in level and in
the time that needs to be devoted to them. For example, the Garden


Watching Birds

Birds Feeding Survey seeks information from anyone who feeds

birds-housewife, housebound or harassed husband. At the moment,
these birdwatchers are witnessing the establishment of the Siskin and
Reed Bunting as garden birds. Elsewhere we have talked in some detail
of the Common Birds Census and Ringing Scheme-both longstanding permanent BTO enquiries. The Birds of Estuaries Survey
seeks facts and figures about the vast international hordes of waders
and wildfowl that winter on our estuaries or use them as vital staging
posts on migration-and these estuaries are just about our most
seriously pressed habitat at the present time, especially threatened by
land reclamation and water storage barrages. The Atlas of Breeding
Birds project, completed in 1972 and soon to be published, has been
succeeded by the Habitat Register, which entails listing and documenting (Domesday Book style) our bird habitats, site by site, so that
planners may be better informed before they start to make their plans.
The Atlas is bound to reveal individual species that need investigation-recently the BTO has been concerned with the Twite,
Water Pipit and Cirl Bunting, and there are plan-s to census Britain's
rookeries. Lastly, the Nest Records Scheme encourages members
(stressing the care that is needed) to visit nests and to record the
sequence of events there, the eggs, the young, and how many successful
fledglings there are. From these figures, we can see how our birds are
doing at this critical recruiting stage of their life cycle.
Not only is it pleasant to participate in this way (and often exciting,
too, when you hold your breath, in close proximity to a flock of geese,
for example, or to avoid disturbing a cock Bullfinch as it approaches
along a hedge, or even just before the garden Robin hops onto your
hand to take a worm), it is rewarding and immensely satisfying. I can do
no better than quote, and agree with, James Fisher's last paragraph:
"Some people like to make paper plans and push them through
regardless of distraction. Others like to wander into a subject and let it
take them where it will. I hope I have been able to give the paper-plan
people some preliminary headings and I hope that for the others I have
given the stream of ornithological thought enough momentum for it to
dislodge them from their rest. Birdwatchers are in some ways like
golfers, who want to convert all their friends to golf. I don't excuse
myself for belonging to this class. If this book succeeds in making new
birdwatchers, I hope they will have a very happy time, though I don't
see how they can help it."

The birds included in the index are those which are dealt with at some length in the book
or are the subject of maps, graphs, etc-briefor passing references to species in the text
have not been indexed.
Adaptations of birds, 16-18, 19
age, of birds, 76-7
anatomy, of birds, 18-34, 45
Beaks, types of, 16, 18, 42
behaviour, of birds, 86-7,115-26
aggression, 119-25, 128--9, 140-2, 146
courtship and mating, 135-6, 137,
140, 146-50
submission, 125-6
territorial, 133-8, 140, 142
adaptations of, 16-18
anatomy of, 18-34, 45
beaks of, 16, 18, 43
breathing of, 27, 28
digestion of, 25
evolution of, 14, 15
feathers of, 21, 22, 33, 45
feet of, 15, 16
flight of, 17-24
legs of, 24
reproduction of, 26, 29, 30-3, 135-6
skeleton of, 18-24
temperature of, 27, 28
wings of, 20-23, 43
Birds of Estuaries Survey, 156
birdwatcher, the, 13-14,39,44
birdwatching, clubs and societies, 152
enjoyment of, IS 1-6
binoculars, 46-50
Blackcock, 120
Black-headed Gull, 123-5
Blue Tit, weights of male and female, 147
books, mentioned in text, 44, 45, 48, 53,
54--{i (list), 98, 105, 121, 123, 148,
149, 152; quotations at chapter
openings are from Gilbert White's
The Natural History of Selborne,
first published 1788
breathing, in birds, 27, 28

British Ornithologists' Union (B.O.U.),

British Trust for Ornithology (B.T.O.),
67,88,101, 155-6
Atlas (provisional maps), 108-9
Field Guides, 48, 53
brooding, 27, 137
Census work (see also Common Bird
Census), 46, 88, 100-1
climate, influence of, 60, 62-4,78-9, 87,
"cline", 37
clothing, for birdwatching, 51
Collared Dove, 61, 106, 108, 109
colouring of birds, 116-32
of adults, 41, 117, 118-25, 127-32,
133, 138
of eggs, 17
of nests, 116
of young, 117
colour-phase, 41, 42
Common Bird Census (C.B.C.), 83,
89-95, 156
graphs, 83, 93-5, 101
maps, 90-1,143-5
commonest birds,
in Britain, 92-5
in World, 99-100
Council for Nature, 152
counting birds, methods of (see also census work) 100-1
County Naturalists' Trust, 154
Crow, Hooded and Carrion, breeding
ranges, 131-2
Digestion of birds, 25
dispersals, 59-60, 61, 74
display, 116, 118-26, 128-9, 134-50
distribution maps, 40, 41, 104-5, 107,

Dunnock, 148




Egg-collecting, threats from, 96, III

colouring, 17, 116
development, 30-3
hatching, 33, 13 7
laying, 136, 147
of Guillemot, 17
shape, 17
egg tooth, 33
equipment, for birdwatching, 46-57
evolution, of birds, 14, 15
Feathers, 21, 22, 23,45
feet, of birds, 15-16
Flicker, 127-8
flight, anatomy of, 17-24, 65
Fulmar, 41, 42, 99, 102-6
Garden Birds Feeding Survey, 155-6
Garganey, 69
generic names, 33
genera, 42-3
Greater Spotted Wood~cker, 107-8
Guillemot, 40-1
classification of, 79-80
heaths and moorland, 85-6
influence of, 78---89, 110-11
mountain, 86
population by, 89, 91, 101
selection of, 86
hatching, 33, 137
heart rate, of birds, 28
hedgegrows, importance of, 85
Heligoland trap, 68, 72
Heron, 95
hibernation, in birds, 27, 65
Holarctic region, 133

Mapping surveys, 90-1, 108-10

melanistic birds, 40-1
migration, 58-77
observed by radar, 73
mist nets, 68-9
moult, 34, 137
National Trust, 154
Nature Conservancy, 88, 153
Nearctic region, 78
navigation, in birds, 64, 65, 77
nests, 116-17, 136
"cock-nests", 136
nest boxes, 48-9
nesting populations (C.B.C. graphs), 93,

nestlings, 137
nidicolous birds, 33
nidifugous birds, 33
nomenclature, of birds, 35,42, 53
note-taking, 45, 52-3, 152-3
numbers of birds, see population
Observatories, bird, 69, 73, 75
Operation Seafarer, 97-8
Palaearctic region, 78
Partridge, 143
photography, 50, 153
"pigeon's milk", 25
pigmentation (see also colouring), 40-1
population, bird, 60, 76, 78-9, 82-7,

Identification, of birds, 43-5, 52, 54,152

irruptions, of birds, 58, 60-1

decrease, 110
estimating, 97, 101-2
in Britain, 88-114
largest, 99-100
of sea birds, 97-100
nesting (C.B.C. graphs), 93, 94, 95
spread of, 102-8
protection of birds, 111-14, 153, 154

"Jizz", in indentification, 44, 52, 152

Radar, in migration study, 73

range, of birds, 37-9,40-1,61-9,78,81,

Lapwing, 63
legs, of birds, 24
life-span of birds, 76-7
Linnaean system, 35
longevity-see life-span
lungs, of birds, 28

rare species, 77, 96, 97, 98, 110

recordings, of bird-song, 56-7
recoveries (ringing), 65, 66, 67-71
Redpoll, 83
Redshank, 149
Reed Bunting, 141

102-8, 131-2

Index 159
Reed Warbler, 68
reproduction, in birds, 26, 29, 30-3,
ringing, bird (see also recoveries), 46,
65-9,70-1,74-7, 156
permits, 67
Robin, 123, 139-40, 148, 149
Royal Society for the Protection of Birds
(R.S.P.B.),77, 113-14, 152, 154
Ruff, 119, 121
St Kilda Wren, 37-9, 96-7
Sedge Warbler, 68
skeleton, of birds, 18-24
Snow Bunting, 120-22
Society for the Promotion of Nature
Reserves, 154
song and calls, of birds, 56-7, 117-18,
123, 129-130, 133, 134, 136-7;
140, 141, 145
recordings of, 56-7
songposts, 141, 145
species, of birds, 35-45, 53
and subspecies, 37-9
definition of, 36-7, 39
specific name, 33, 39
stalking, 51-2
Stock Dove, 149-50

study techniques, migration, 65-77

sub-species, of birds, 37-9, 42
Swallow, 74
Tape recorderS, 46, 52, 57
temperature, body, of birds, 27, 28
defined, 133, 138
in winter, 138-140
securing and holding of, 133-8
size and shape of, 142-5
Vertebrae, of birds, 18, 24
Weather, influence of-see climate
weight, of birds, 65, 147-8
Whitefront, 66
Whitethroat, 94, 145
Wildfowl Trust, 154
Wilson's Petrel, 99-100
wings, of birds, 20-3,43
woodland habitats,
coniferous, 79, 81-2
deciduous, 79, 82-3
mixed, 79, 83-4
Workers' Educational Association
Wren (see also St Kilda Wren), 144

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THE BRITISH TRUST FOR ORNITHOLOGY: a network of thousands of

amateur birdwatchers collaborating with a small professional staff to

find the facts on which the welfare of our birds depends. The BTO
organises field work. runs the Ringing Scheme. maps bird distribution.
New investigations include a national habitat register. Whenever birds
are threatened the BTO comes forward with proposals and countermeasures based on sound scientific knowledge. All bird lovers are
welcome. Active ones for the field work. others for their important moral
and financial support. Members receive a quarterly journal Bird Study
and BTO News. an informal bulletin for birdwatchers. seven times a year
as well as other privileges.
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