Feathers are unique to birds among living animals, and no other group has them.

The longer version

A feather grows out of a small pit in the skin as a branched shaft carrying hundreds of barbs, each barb carrying even smaller barbules that hook together like a zipper. That interlocking design gives a light, stiff, repairable surface. Nothing else alive builds a body covering this way, because reptile scales, mammal hair and insect wings come from other tissues and fold quite differently.

Feathered fossils turn up in the record of two-legged dinosaurs, so the structure long predates birds themselves. What birds added was the large, asymmetric flight feather with a locking vane. Feathers also wear out, which is why birds replace them on a schedule instead of growing one set for life.

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.