The male mountain bluebird is brilliant blue all over, while the female is gray overall with pale-blue wing and tail feathers ...

STANFORD – On a stretch of Dry Wolf Road, a pair of bluebirds are working their tail feathers off flitting in and out of a nest box. Inside, five chicks are wedged together in a nest awaiting ...

The precise design of this bluebird wing is a blueprint for flight. The feathers are light but strong and flexible. The outside feathers are the contour ones.

Then from there is the feather of a black-headed parrot, the typical eyespots of a great argus pheasant, the plumage of a blue bird-of-paradise (pictured above) and the tail feathers of a grey ...

Shimmery. Spiky. Shaggy. Soft. Feathers are what make birds so alluring—but these photographs remind us that they also tell a story about the science of evolution.