The Incredible Egg

Tim Birkhead’s The Most Perfect Thing: Inside (and Outside) a Bird’s Egg is a perfect thing in and of itself. This a short but intense look at what we know and don’t know about bird eggs. We know an awful lot because of hens and the billions of chicken eggs that are produced every year around the world. Yet there is still much that is not known about eggs. Especially those produced by the many other species of birds out there.

Here’s something that was cleared up for me. In temperate zones, the low ambient temperatures can keep eggs in suspended animation for two or more weeks. Birds generally only lay one egg a day, and some clutches have as many as ten eggs. Incubation doesn’t have to start until they’re all in the nest.

And blue eggs? American Robins are famous for them, but this color is not uncommon among open-nest builders. They certainly seem very visible to predators. But this threat may be balanced against the blue part of the light spectrum being absorbed by the embryo, which reduces the duration of incubation and hence vulnerability to predation.

Also, what you may know about extremely pyriform guillemot eggs safely rolling around in a circle on a narrow cliff is wrong. This standard story is based on empty egg shells, the blown eggs once so feverishly collected around the world. (A few collectors still persist in threatening endangered birds, especially in the UK.)

Birkhead does the egg in vinegar trick too.
Chicken eggs from a Westchester Co. backyard.

It’s books all week here. Please don’t use Amazon, whose “fulfillment center” sweatshops are permanently maiming workers.The ruthless company has twice the national average of severe injuries on the job. Yesterday also saw another report on the exploitative conditions right here in NYC, in the Amazon sweatshop on Staten Island.