The most perfect thing - inside (and outside) a bird's egg

| 7th June 2016
'The most perfect thing - inside (and outside ) a bird's egg' - from front cover.
'The most perfect thing - inside (and outside ) a bird's egg' - from front cover.
Birds eggs are wonderful, as Tim Birkhead makes clear in his new book. But they are also enigmatic, mysterious, their secrets not lightly surrendered. Every kind of egg is perfect in its own way, writes Martin Spray, but the logic that underlies their characteristic designs, colours and shapes eludes the most assiduous of oologists.
He draws many species into his story: blue tits and blackbirds, woodpeckers and wrens, Spix's macaws and zebra finches included. And he provides a raft of references from the long history of ornithology.

In my experience, this is an unusual book. My experience, that is, of bird books ... It is probably the only one I've read from start to finish.

Ornithology is not my thing; and oology - the study of eggs - something I'd not thought about.

Tim Birkhead's book has bridged a gap in my biological understanding, and I suspect it will do the same for other people who happen on it.

Birds' eggs have long fascinated some people, most of them doubtless not scientists. The focus of their interest is on the aesthetics of the individual eggs and of neatly arranged collections of them - that, and the near-craving to have the biggest, most numerous collection of something.

The fanatical amassing of empty eggshells by some collectors is several times discussed, most horrendously in the Epilogue. Rich and clearly eccentric Vivian Hewitt gathered hoards of them (and many other things). At his death he had accumulated about half a million eggs.

Four large removal lorries took them to their new home, where their new owners, the British Trust for Ornithology, must have felt sorely daunted. The image is obscene - and all the more so because the documentation of the 'collection' is minimal and chaotic.

Nonetheless, Birkhead shows that some science can be winnowed from such death-piles - and, indeed, he emphasises the shift of endeavour from collecting to investigation, or to wanting to protect, that enthusiasts for birds' eggs - or butterflies, or flowers - frequently undergo. He gives as examples Mark Cocker, Bill Oddie, and David Attenborough.

From collection to understanding

But this is not the meat of the book. That is the search for an understanding of what a bird is about when it is a developing knot of cells atop a depot of food (yolk) within a water reserve and antimicrobial barrier (albumen), which its mother has just enveloped in intricate coats of calcium carbonate, and then perhaps coloured and marked (the 'shell').

The book's central chapters deal with 'Making shells', 'The shape of eggs', 'Colouring eggs', albumen and 'the Microbe war', 'Yolk, ovaries and fertilisation', and the chore of 'Laying, incubation and hatching'.

The author's main interest is guillemots, but his knowledge is far wider and deeper than just these. He draws many species into his story: blue tits and blackbirds, woodpeckers and wrens, Spix's macaws and zebra finches included. And he provides a raft of references from the long history of ornithology.

The reader learns not only about bird biology. The rigorous caution and skepticism that Birkhead shows throughout his text is a good example of the way some biological science advances. Many times he has revisited an earlier, accepted, understanding, reinvestigated, and drawn fresh, different, conclusions.

It is good to see a scientist conclude that he is wrong; even better to see him admit a simple - but for so many of us a painful and shameful - 'I don't know!' ... And it seems we don't know, for instance, why some birds lay eggs that are nearly spherical, others that are distinctly pointed; why some have plain eggs, some others have colourful or elaborately marked ones, and some lay different-looking eggs at different times.

The egg came long, long before the chicken - and others birds

This is not a textbook or treatise. It is lucid, written in an enthusiastic, non-scientific, sometimes colloquial, prose, although perhaps let down by some of its few line drawings being rather uninformative, and by a somewhat limited range of colour photos.

However, for me an important aspect is largely lacking. What we call 'eggs' are fundamental to animal life. Reptiles, including dinosaurs, have a few mentions, as do amphibians, but there is almost nothing to remind the reader of eggs of other creatures.

There is little to demonstrate how the eggs of birds are like or unlike those of other animals, how the egg-phase of animals has evolved, and indeed how one might define the avian egg to show how it is unique. Fish, slugs, moths, and earthworms have eggs, and it may be (to us) that except aesthetically they too are the most perfect things.

This latest book joins such titles as The magpies, The wisdom of birds, and Sperm competition in birds. I may be tempted to read some of them.



The book: 'The Most Perfect Thing - Inside (and Outside) a Bird's Egg' is by Tim Birkhead and published by Bloomsbury (288 pp, hardback, £16.99).

Martin Spray is an editor and writer for Ecos - A review of conservation.

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