Much of my scientific career has been spent trying to understand how sperm fertilise eggs. For a long time birds were thought to be mainly monogamous, but in the 1980s it was recognised that even though most birds do indeed breed in pairs, and can therefore be thought of as ‘socially monogamous’, they are anything but sexually monogamous. Extra-pair copulations are frequent, and result in extra-pair paternity, as confirmed routinely now through the use of DNA-fingerprinting. Female promiscuity results in ‘sperm competition’, and for the last thirty-odd years I have tried to understand how the sperm from different males compete to fertilise a female’s eggs.  Specifically, I wanted know if a female copulates with more than one male, are there any rules that determine which of those males will fertilise her eggs? There are, and that particular story is in the book.

After years of focusing on sperm however, I thought it was about time I looked at eggs. Several things brought about this switch to eggs. One was that a number of my students having completed their PhD research had gone off to start their own reproduction and I was intrigued by the ‘new life’ they were creating. Another was a long-standing fascination with guillemots and their extraordinary suite of adaptations for breeding on open cliff ledges. If you think about it, breeding on a narrow cliff ledge with no nest, and shoulder-to-shoulder with a lot of other guillemots is pretty extreme. Little wonder that guillemots have so many unusual features. The best known of these is their egg, whose pointed shape was said to be an adaptation that allowed the egg to spin ‘like a top’ and not roll off the cliff ledge. In fact, that idea was shown to be wrong over a century ago. The egg does not spin on the spot, rather, it rolls in an arc and experiments I conducted on Skomer Island, Wales in the 1970s showed that the arc described by a rolling guillemot egg is much wider than many of the ledges guillemots breed on. Hardly convincing evidence that the shape was an adaptation to minimize rolling! Then in 2012 I was surprised to see the spinning on the spot story resurrected and even ‘demonstrated’ on television. I was both disappointed, but it made me realise — the story is told in the book — that guillemot egg-shape might merit another look.

I started, and one thing led to another, and before I knew it, I was reading everything I could find about eggs. This book is the result.

The title comes from the nineteenth century ornithologist Thomas Higginson, who regarded a bird’s egg as ‘the most perfect thing’.

Birds’ eggs are perfect and their aesthetic appeal led many boys and men (it was never girls or women as far as I can see) to collect them. In the Victorian era and early part of the twentieth-century egg collecting was a (fairly) respectable and popular pastime. Charles Darwin wrote in his biography, that as a boy: I was very fond of collecting eggs, but I never took more than a single egg out of a bird’s nest, except on one single occasion, when I took all, not for their value, but from a sort of bravado.

Darwin wasn’t alone, and many of today’s ornithologists – including Mark Cocker, David Attenborough and others — collected eggs as boys. What’s more they recognised how important that intimacy with nature was in developing their subsequent feeling for the natural world. They all grew out of collecting. But some didn’t, and in 1954 when collecting became illegal, those men who couldn’t resist the oological temptation, went underground. I focus on one such collector, and what a curious man he was, for he collected only guillemot eggs. His collection of some 2000 guillemot eggs are now in a museum, and they’ve been important for my research.

A micro-CT scan of a bird’s eggshell