In late summer and autumn, millions of birds fly above our heads, often at night, winging their way toward their wintering grounds.
Before the journey, many birds moult their bright feathers, replacing them with a more subdued palette. Watching this moult led scientists to wonder how feather colour changes relate to the migrations many birds undertake twice each year. Moult matters — not only because replacing worn feathers is necessary for flight, but because moult is the catalyst for plumage changes that affect whether birds find mates and reproduce. MORE
Header image: A golden-crowned Kinglet in Bluebonnet Swamp, Louisiana. Credit: John Hartgerink.