Feathers are amazing structures. But after about a year, constant use and exposure to the elements mean they have to be replaced. So how do you replace the roughly 20 feathers in each wing that are essential to flight? Many species — such as this Common Raven — molt just a few feathers at a time so they can still fly. But waterbirds like ducks and loons molt all of their flight feathers at once. As a result, they’re earthbound and vulnerable to predators for a month or more — until their full suite of feathers has been completely restored.

More info and transcript at BirdNote.org. 

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