WHAT IS A BLUEBIRD?
The Bluebird is a member of the thrush family related to the American
Robin. The Eastern Bluebird (Sialia sialis) is generally found in the
eastern half of North America to the Rocky Mountains. The Mountain
Bluebird (Sialia currucoides) is found from the eastern foothills of the
Rocky Mountains west to the Pacific coast of the North America. The
Western Bluebird (Sialia mexicana) is typically found west of the Rocky
Mountains. All three species are blue on the back. The Eastern has a red
breast and white belly. The Mountain is slightly larger than the Eastern
and does not have the red breast. The Western is similar to the Eastern
with the red of the breast spreading around to the back.
Bluebirds are NOT Bluejays, Indigo Buntings, or any
other bird species that is blue.
WHAT IS ACCEPTABLE BLUEBIRD HABITAT?
The natural habitat of Bluebirds are open fields, prairies, and
meadows with few trees or shrubs. The natural nest location is an old
woodpecker hole or rotted (hollow) limb on a tree. The artificial
habitat that man has created that is usable by the Bluebird includes
broome fields, horse and cattle pastures, cemeteries, golf courses etc.
This artificial habitat should be one that does not include the use of
pesticides, as they can be harmful to the insect eating birds. Man has
taken up the Bluebird cause and has created nest boxes for the Bluebirds
on both the natural and artificial habitat areas. Woodland habitat is
less favorable to bluebirds, but there are a number of other species
that would make use of a Bluebird nest box in such habitat. These would
include House Wrens, Chickadees, Great-Crested Flycatcher, Nuthatches,
Titmice. Placing a Bluebird box in woodland habitat is not necessarily
bad but, Bluebirds nesting there would probably be usurped by other
birds (most probably house wrens). Where house wrens or flying
squirrels are present in your area then these two species may take over
use of your bluebird nestboxes in mostly wooded areas. Other wrens are
not considered a problem.
WHAT IS A BLUEBIRD TRAIL?
A loose definition of a Bluebird trail is a single Bluebird nest box,
monitored for the removal of undesirable birds (House sparrows). Many
trails are much longer, some consisting of hundreds of boxes. A more
typical trail might consist of six to thirty boxes. Naturally the trail
should be in the best Bluebird habitat available in the area.
WHAT IS A BLUEBIRD NEST BOX?
There are many good Bluebird nest box designs. Such as Peterson's,
Gilbertson's, NABS, slot box, and the many variations of these boxes.
What constitutes a good box is primarily a box that the bluebird's will
use, you can monitor, and the predators can't get into.
The entrance hole for Eastern and Western Bluebirds should be one and
one-half inches in diameter (the Peterson Box hole size is an oval
(1&3/8" x 2&1/4") and Mountain Bluebirds should have a
one and nine-sixteenths inch hole or (Peterson, 1&1/2" x 2
1/4"). Not to confuse the issue but a well respected
bluebirder, Keith Kridler, makes the following comments on the use of
the oval Peterson entrance: "Well the Peterson Oval entrance
1&3/8" wide is a KNOWN AND PROVEN entrance that allows
starlings from all over north America to "easily enter and leave
nestboxes." The last is a quote from Kevin Berner's article! For
the last 70 years bluebird conservationists have fought to educate the
public to use an entrance hole to "positively exclude ALL
The box material should be untreated wood such as cedar or redwood.
It is acceptable to use pine but under no circumstances should the box
be painted on the inside. Do not use the cardboard boxes that some of
the schools have allowed students to paint as Bluebird boxes.
Ventilation is also another key ingredient in good box design. In
colder climates the ventilation holes can be plugged until warm weather
WHERE CAN I OBTAIN BLUEBIRD BOXES FROM?
There are many reputable dealers that build good nest boxes. The
designers of boxes themselves (such as Steve Gilbertson) sell boxes that
they build. State Bluebird organizations often sell nest boxes or
recommend nest box manufacturers. A list of nest box dealers is included
at the end of the FAQ. Garden centers, nurseries, and nature stores sell
boxes but be careful, often their boxes are of inferior design (they
can't be opened for cleaning, have a perch, entrance hole wrong size,
etc). Nature store boxes also tend to be expensive when compared to
boxes from other sources.
WHERE SHOULD NEST BOXES BE PLACED?
Ideally the nest box should be placed on a metal post, such as a
fence post or electrical conduit that is not part of a fence line. The
boxes should be 50 feet from nearby bushes and trees and 200 feet if
house wrens are a problem. The nest boxes should be placed about 200 to
300 feet apart. I generally place mine such that the view from one box
to the next is obscured by distance, an obstruction (such as a hill,
tree, etc), or other barrier. If Tree Swallows are using your boxes then
the boxes should be paired (distance between boxes (15 to 22')), then
spaced 300 feet to next pair.
The nest box should be placed no higher than what is convenient to
monitor. Bluebirds will actually tolerate boxes mounted much higher
(twenty feet) or as low as three feet. I recommend five feet as this is
a height that most people can monitor easily (The real experts will
suggest five feet as a minimum).
The opening of the nest box should be directed away from prevailing
winds to prevent rain from being blown into the box opening. The birds
themselves don't mind which direction the opening faces, but if the
fledglings are exposed to moisture and cold this can cause hypothermia.
When specific orientation is an option orient the box opening away from
the hottest exposure to the sun away from the nest box opening. Although
any box orientation might be used reports indicate the most often
selected and most successful box has the hole facing either east or
slightly northeast. The boxes can placed around a field in a circle to
make a monitoring circle.
HOW DO I MONITOR MY BLUEBIRD TRAIL?
Boxes should be in place (if taken down in the winter) or cleaned and
unplugged (if plugged to prevent mice or house sparrows from roosting in
the box) early in the year (late February or early March).
Box monitoring can be started slowly in the early part of the season
(every other week is sufficient). When nest building begins the boxes
should be monitored on a weekly basis as a minimum, and no more often
than twice a week. Monitor weekly only until nestlings are 12-13 days,
then after they fledge remove old nesting material then resume weekly
monitoring. Weekly monitoring should continue until the season is over
(usually mid August). The box should be checked and closed as quickly as
possible. You should spend as little time at the box as necessary to
prevent scaring off any possible nesting Bluebirds. Western
Bluebirds fledge at an average of 21 days.
When checking the box all House Sparrow nests should be removed along
with eggs. The House Sparrow eggs should be destroyed or can be taken to
a local nature center for feeding to snakes. If box monitoring is done
on a weekly basis, house sparrows may be able to build a nest and lay
eggs but they will have insufficient time to hatch the eggs. Many
bluebirders trap House Sparrows but that presents a problem for some in
that the captured birds must be destroyed.
There will be other nests found in the nest boxes, typically these will
be from House Wrens, Nuthatches, Great-Crested Flycatchers, Chickadees,
Titmice and other cavity nesting birds. These other species with the
exception of the House Wren will not cause trouble on your Bluebird
trail. It is a violation of Federal law to disturb all of these species
while nesting However, many bluebirders will remove dummy House Wren
nests (Boxes filled to the top with sticks). Removing wren sticks placed
by the male is legal; the nest is the cup the female puts on top of the
sticks, and that of course is protected by federal and state laws. Also
house wrens are a very territorial bird and can cause considerable
problems on a Bluebird trail.
Old Bluebird nests should be removed after the babies have fledged. I
have found that failing to remove the nests will result in the nest
being invaded by ants after the birds have fledged. There is a new
school of thought that the old nest should be left. I feel that might be
acceptable for the last brood of the season but not until then. There
are studies that indicate Bluebirds are predisposed to use a box with an
old nest in it.
HOW DO I KNOW WHEN I HAVE A BLUEBIRD NEST IN MY NEST BOX?
It is actually very easy to determine a Bluebird nest. Bluebirds have
a very neat nest made from fine grasses (occasionally pine needles) in a
nice cup shape. Typically there will be no seed heads, cigarette butts,
strings, sticks, or other junk in a Bluebird nest. Occasionally there
will be some cattle or horse hair in the Bluebird nest. Bluebirds keep
the nest relatively neat by removing fecal sacs and other debris. Dick
Purvis who is a well know bluebirder informs me that "Western
bluebirds primarily make their nests out of dry grass. However, they
will use anything conveniently near that is equivalent. Many of mine
make their nest entirely of conifer needles. They may be influenced by
the fact that some of the conifers here have needles that are very long
up to 6 to 8 inches. Bluebirds whose nestboxes are in cottonwood trees
use the inner bark of the cottonwood for their nest. This is a soft thin
material similar to grass. At Easter time, many of my bluebirds in
public parks make their entire nest out of green Easter basket confetti!
In general, most nests have a couple of small feathers in them. They
usually have a piece or two of cellophane in the cup. They will also try
to use artificial items like twine or monofilament fish line. I have
found a few dead birds, both adults and young, tangled in nest material
House Wren nests are mainly sticks, about two to three inches longs.
They may line the very top of the nest with grass or hair. Often House
Wrens will bring spider egg sacs into the nest.
House Sparrows nests are made from grass, but are very loosely made
and will include a collection of a variety of trash, including:
cigarette butts, string, feathers, and just about anything else they can
pick up. One big clue is seed heads in the nest. The nest usually has no
bottom and has a domed top.
Chickadee nests are usually made from moss and lined with hair or
down, in general appear to be a quite comfortable place to be born.
Mice also use nest boxes and are more a threat to the monitor than to
the bluebirds. There is a virus that can be acquired through mice
droppings and therefore caution should be exercised when cleaning out a
mouse nest. The mouse nest will usually consist of milkweed pods. Always
stand up wind of the box when removing these nest and do so with a stick
or brush (not with your hand).
As stated before other cavity nesting birds will use Bluebird nest
boxes but none of these birds are a threat to bluebirds. In fact if
another bird is using the nest box consider yourself lucky to be able to
enjoy another species. Other species using your nest box might be an
indication that the area you selected for this nest box is inappropriate
for Bluebirds (NOTE: I'm not suggesting you remove this box, just that
this is not Bluebird habitat).
I HAVE HEARD OF RECORD KEEPING, WHAT IS IT AND WHY IS IT DONE?
A record of what was observed at the nest box should be maintained
for each box on the trail. This information should include dates, number
of eggs laid, eggs hatched, birds fledged. This information is important
to many Bluebird organizations including your state's Bluebird
organization and the North American Bluebird Society. The organizations
have forms to be filled out and sent in at the end of the Bluebird
season. These organizations use this information to obtain trends on the
breeding success of Bluebirds in their areas. Also it can help to
determine which boxes work the best in certain areas. These records
provide you with information as to what boxes are producing and which
boxes are proving to be a problem with predators. At the end of the
season it is comforting to know how many Bluebirds fledged from your
WHAT BLUEBIRD PREDATORS CAN I EXPECT TO FIND?
If you are using proper Bluebird nest boxes that will eliminate
starlings from usurping Bluebirds from your nest boxes. That only
eliminates one of the many predators. The two biggest predators are
House Sparrows and House Wrens. These birds will usurp nest boxes, they
have been known to break eggs, kill babies and adults, build nest over
Bluebird nest, etc. In recent years much concern has been expressed
about the effects of House Wrens on other nesting birds. House Wrens,
unlike most other song birds, are territorial toward ALL other species,
not just their own. Other predators include Bull snakes, Blowflies,
ants, cats, raccoons, squirrels, etc. There are predator guards
available to prevent some predation, other times such as with Blowflies
and ants a specialized insecticide is needed like a natural pyrethrum
insecticide IF and only IF blowflies are there in huge numbers and even
then better to either lift up the nest, gently shake and brush out larva
or make a new nest of fresh dry grass and replace the old one. I have
known bluebirders to carry an old bluebird nest to be used in the
replacement of a infested or extremely wet nest. CAUTION: tampering with
the nest or possession of an old nest is technically illegal (yes, even
by a bluebird trail monitor). Extreme caution is urged when using
insecticides please use sparingly as they can prove harmful to the
fledglings, adults, and bluebird monitors.
WILL BLUEBIRDS COME TO MY FEEDERS?
Bluebirds will come to your feeder if you provide the right kind of
food. The Bluebird food of choice is insects. You can provide this food
by giving them mealworms. Mealworms can be acquired from pet supply
stores, nature stores, and by mail order. Occasionally Bluebirds will
come to feeders for seed, but this is usually done when insects are in
short supply. Much like the other members of the Thrush family
they will also eat small berries such as cranberries.
IS IT UNUSUAL FOR BLUEBIRDS TO OVER WINTER IN MY AREA?
In the winter the Southern states play host to a great number of
Bluebirds that have migrated from the Northern states and Canada.
It seems to be more common for Bluebirds to over winter in the
North. The reasons are most likely very numerous.
Speculation includes improved numbers have caused more birds to
over winter in their native nesting territories giving them an advantage
when spring arrives to be first in the area. This gives the males
a better chance of getting a nest box in the best habitat. This
over wintering most likely is influenced by a greater number of humans
providing the necessary ingredients to make survival possible.
That would include roost boxes and food. It is probable that
some of these over wintering birds will not survive the winter but just
as likely many migrating birds do not survive the migration process.
It is likely that both migration and over wintering should help
produce a more durable species in the long run. Humans played a
part in the decline of natural habitat for the birds and it is only
logical that they provide an artificial habitat as a replacement.
WHERE CAN I GO FOR MORE HELP?
- There are a number of places to go for assistance for Bluebird
problems and questions. The first thing I recommend is to get a good
Bluebird book. The one I recommend is "Bluebird Trails-A Guide
To Success" by Dorene Scriven. This was written by a bluebirder
for bluebirders. It has nest descriptions, box types and plans,
monitoring forms. In other words all the help you could ask for.
Other good Bluebird books are "The Bluebird-How You Can Help It
Fight for Survival" by Lawrence Zeleny of NABS and
"Enjoying Bluebirds More" by Julie Zickefoose (published
by Bird Watcher's Digest). Next find the name and address of your
state Bluebird organization (see list at end of this FAQ). The state
organization usually has people in your area that can help with box
type selection for your area, specific predator suggestions,
workshops, a newsletter, and often a state conference to discuss the
many bluebirder related concerns. These groups are usually supported
through donations or through your state non-game wildlife program.
Another worthwhile Bluebird organization is The North American
Bluebird Society (NABS). This organization exists on the dues and
donations of it's members. It is devoted "...to increase the
populations of the three species of Bluebirds on this
continent." NABS publishes a quarterly journal (Bluebird),
offers grants for Bluebird research projects, publishes results of
Bluebird research, has a nationwide Bluebird Conference, etc.
- Ask questions, all the bluebirders I've ever met are always very
happy to share their knowledge and Bluebird stories with anyone
willing to listen. For bluebirders, Bluebirds become part of their
life, almost a part of their family - let them show you their kids.
- The internet is gaining the attention of bluebirders. Here
is a list of Bluebird and other cavity nester web sites set up by
Personal Bluebird Pages
The following individuals, books, and materials were useful to
me in creating this FAQ: