Bird beaks, or bills, come in many shapes and sizes. And birds use them for just about everything: to collect food, preen, fight, court (as this pair of Laysan Albatrosses is doing), chop holes in trees, weave nests, and more. In order for a bird to fly, its beak must weigh as little as possible. Beaks are covered with a sheath of a tough material called keratin, which grows continuously because a beak wears down with use.

More info and transcript at BirdNote.org. 

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