This is bird note.

How long can a bird fly without once touching the earth or alighting to perch?

Experts have speculated for years that some kinds of swifts spent long

continuous periods of their lives in the air. To figure out exactly what they get up to,

Swiss scientists began researching Alpine Swift's,

a large species with a wingspan of over two feet.

The research published in 2013 involved attaching sensors to some of the swifts

while they were nesting in Europe and recovering them on the birds return from spending

winter in Africa.

It was already known that the swifts eat on the wing,

but what about sleep?

The sensors showed long periods when the swifts were gliding and not

flapping their wings. But scientists aren't sure if that means the birds were

asleep. Could be that like some other animals, Alpine Swift's do all they're sleeping during the summer breeding season and don't sleep at all during migration.

As for why they stay aloft so long, while they're supreme flyers,

SWIFT's find landing complicated.

They can't perch because they have very short legs.

So, if they can manage it, avoiding touching down makes perfect sense.

For Bird Note, I'm Michael Stein.

Bird Note gives you the sounds of birds every day,

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