Birds that rapidly moult feathers are more likely to become flightless

By Jake Buehler

Visions from Earth/Alamy

From ostriches to kakapo parrots to flightless ducks, birds have lost the ability to fly many times. But some groups of birds end up grounded more often than others, and now it seems that those that moult feathers from both wings at once may be predisposed to evolving flightlessness.

Ryan Terrill at Occidental College in Los Angeles, California, was fascinated by moulting, the process by which birds shed and replace old feathers. As a graduate student at Louisiana State University in Baton Rouge, he was thinking about flightless …