After ruling out diet, scientists discover the secret behind blue feathers lies inside how the feathers are made. Gavriel Jecan / Corbis For decades, scientists have known how birds with yellow or ...

Males have bright yellow feathers covering most of their bodies, with a reddish-brown “cap” atop their heads during the breeding season. They are territorial birds that defend their turf from ...

White or yellow throat. Black streaks on upper breast and side. White wing bars. White spots in outer tail feathers. Spring female: similar to male, but brownish above with smaller tail spots.