This is bird note.

Swirling overhead, dozens of birds swoop and glide in pursuit of insects.

Are they swallows or swift? swoop and glide in pursuit of insects.

Are they swallows or swifts?

How in the world do you tell them apart?

At a glance, swallows and swifts look much alike.

They're graceful flyers on long slender wings and all about the same size.

But a closer look reveals key differences.

Swifts have longer, even slimmer wings and relatively shorter bodies.

Swifts also glide for longer periods.

Their glides are punctuated by rapid, stiff bursts of wing beats.

Movements so brisk their wings seem to flicker.

Swallows, on the other hand, flex and flap their wings.

Why do Swift have such a peculiar stiff wing stroke?

Picture a typical bird wing, with two halves jointed in the middle.

A swift wing reveals an inner half that's extremely short and an outer portion that's very long.

This causes the stiffness. Try waving your arms with your

elbows held against your body and you'll get the idea. Another group of birds

shares this distinctive wing structure, hummingbirds, and swifts are considered to be closely related to hummingbirds.

Swallows, on the other hand, are songbirds, closer kin of birds like Robbins and Rand.

For Bird Note, I'm Michael Stein.