Birds that rapidly moult feathers are more likely to become flightless
From ostriches to kakapo parrots to flightless ducks, birds have discarded their ability to fly many times. But some groups of birds end up grounded more regularly than others, and now it seems that birds that moult the feathers off both their wings at once may be predisposed to evolving flightlessness.
Ryan Terrill at Occidental College in Los Angeles in the US 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 …