This is Bird Note.

Bird beaks, or bills, come in many shapes and sizes, and birds use them for just about everything,

to collect food, to prine, fight, court, chop holes in trees, weave nests, and more.

But in order for a bird to fly, its beak must weigh as little as possible,

so be beaks have evolved to be ultra-light, like birds hollow bones and feathers. Just what is

this versatile appendage made of? At its core, both upper and lower halves of a beak contain

light bony projections that extend from the skull.

These bony parts are covered with a sheath of a tough material called keratin.

It's the same stuff that makes up tortoise shells, the scales and claws of reptiles, and our own hair and fingernails.

The keratin sheath makes the beak tough, durable, and shiny.

The sheath grows continuously because a beak wears down with use.

Picture a shorebird, like this black oyster catcher,

flipping rocks and hammering shells all day.

Ancient birds were weighed down with jaws and teeth,

making flight far more challenging.

But the beak of a modern bird,

whether it belongs to an eagle,

toucan, or hummingbird,

is a marvel fit for life on the wing.

For Bird Note, I'm Mary McCann.

Today's show, brought to you by the Bobbling Foundation.