

Many questions remain, but decades of study have elucidated so many of the puzzles regarding birds’ eggs that Professor Birkhead has been able to write a whole book about them. It is a fascinating, entertaining and always enlightening journey through the world of eggs, from fertilisation and formation through laying, incubating and hatching, with all kinds of probing, questioning byways examining shape, size, colour and so on. The very idea that a minute blob of near-nothing can develop inside an egg and pop out as a fully formed animal is astonishing. Rather like the metamorphosis of flying insects, it is almost too remarkable for us to grasp.

Like many people, I often contemplate how fantastically complicated and brilliant life is: all the complex physics, chemistry and bio-engineering that goes into the successive stages of a Scottish midge or a gnat, only for us to swat it at the first opportunity; the structure and chemistry that allows a bit of grass to function, only to be cut short by the lawnmower. Likewise the wonder of an egg, honed by millions of years of improvements, only for us to crack the shell and discard it, and cook the insides for breakfast.

This book is full of wonder: the way a Goldcrest pumps its legs full of hot blood to allow such a tiny scrap of bird to incubate a big clutch of eggs; or how a brood of chicks communicate with each other and with their parents before they even emerge, before they have even seen the light of day, to achieve synchronous hatching and instant recognition; the way an egg journeys through the body of a bird and turns horizontally before it’s laid. How do Common Guillemots really apply all that complicated colour to an eggshell? Can you figure out a way to replicate it? Why are some eggs plain white? How does a bird ‘know’ that it must eat calcium the evening before it forms a new egg? How does it even ‘know’ what calcium is? Why do Pied Flycatchers eat woodlice to achieve this, while Great Tits don’t and suffer eggshell thinning through a lack of snails? So many questions. Luckily we have Tim Birkhead and his colleagues to try to answer them: and with his continuing output of books we have a fine communicator continuing to explain what the rest of us have been missing.
  • The Most Perfect Thing: Inside (and Outside) a Bird’s Egg by Tim Birkhead (Bloomsbury, London, 2016)
  • 304 pages, 8-page colour plate section
  • ISBN 9781408851258. Hbk, £16.99. Available from the Birdwatch Bookshop here