Bird eggs come in many colours, from plain white to speckled pale blue.

The longer version

Eggshell colour comes from two pigments laid down in the shell gland just before laying. One produces blue and green tones and is deposited through most of the shell thickness. The other makes browns and reds and sits mostly in speckles and blotches near the surface. A plain white egg has almost none of either.

Colour is not decoration. Speckles break up the outline and help hide a clutch on open ground, while a blue shell may signal something about the mother's condition to her mate. Cavity nesters, whose eggs sit in the dark, tend toward white. Ground nesters with exposed eggs tend toward heavy marking matched to local soil.

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.