A kiwi lays an egg that is very large compared with its own body.

The longer version

A kiwi egg can take up a large fraction of the female's own body volume, and producing it costs so much calcium and energy that she feeds heavily beforehand and is visibly distended. The shell is thin and smooth, and the egg is laid into a burrow rather than an open nest.

The chick that emerges is well developed, feathered and mobile, and it feeds itself within days instead of being fed at a nest. A large egg buys that independence. Birds raising helpless naked chicks lay eggs that are small for their size. The kiwi also runs a low body temperature and a long incubation, both unusual.

Where this entry sits

Here you will find feathered trivia about flight, migration, nests, eggs, and the songs birds sing. Expect short surprising facts on penguins, owls, hummingbirds, and other familiar birds from gardens, forests, wetlands, and distant coastlines. The full list sits on the Birds page, where every entry is listed in order.