This is Bird Note.

Some birds are much more efficient flyers than others.

They get more power out of each flap of the wing.

Birds that capture their food with their beaks while in flight are the best flyers of all.

But there's a trade-off. Feet have many uses,

but for a flying bird, they're a drag, literally. So birds that pursue prey on the wing have

evolved weaker feet than other birds, just like with airplanes and rockets. Reducing the weight

of anything not needed for propulsion increases

flight efficiency. Both swallows, which snatch flying insects out of the air, and hummingbirds,

which catch their prey and gather nectar in flight, have weak feet. They can perch, but they can't

walk.

And swifts, the birds most highly adapted for flight, have such weak feet that they can't even perch.

They can only hang by their long claws or shuffle a few inches.

But in return, swifts can fly rapidly and efficiently, and they have great maneuverability.

They and their close relatives, those hummingbirds, are the only birds that can fly straight up.

That enables the swifts to exit chimneys and cavities and trees where they nest. Now that's an efficient flyer.

For Bird Note, I'm Mary McCann.