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This is BirdNote.

In a beautiful, dramatic, and at times deadly aerial ballet, a Peregrine Falcon dives on a flock of Dunlins. Seeking escape, the shorebirds flash white and dark, rippling through the sky.  

Recent years have seen dramatic changes in this dance. Since the banning of the pesticide DDT in 1973, Peregrine numbers have increased dramatically on both the Atlantic and Pacific coasts. In response, Dunlins have adapted.

For one thing, they've gotten lighter and faster, according to Dr. Ron Ydenberg (EYE-den-berg) and his colleagues at Simon Fraser University in British Columbia. To avoid vulnerable roosting, Dunlins are spending an average of three hours more a day in the air.

Their response to heightened danger has substantially reduced their reserves of fat. And when feeding, birds in the West are gathering more frequently on wide-open mud flats like British Columbia’s Boundary Bay and avoiding enclosed tidal inlets. As Ydenberg puts it, the Dunlin are defending their survival in a variety of ways that trade off food, rest, and safety. And in reviewing 30 years of research he has seen no persistent sharp decline in Dunlin numbers. 

As to whether succeeding generations of Dunlins will continue to adapt to be lighter, faster, and more often in flight, only time will tell.

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Credits: 

Written by Todd Peterson

Narrator : Mary McCann

Producer: John Kessler

Executive Producer: Dominic Black

Bird sounds provided by The Macaulay Library of Natural Sounds at the Cornell Lab of Ornithology, Ithaca, New York. Dunlins [59435 and 135492] recorded by W W H Gunn; [138217] recorded by Gerrit Vyn.

BirdNote’s theme music was composed and played by Nancy Rumbel and John Kessler.

© 2015 Tune In to Nature.org  June 2017/2019 

ID# DUNL-01-2015-06-15 DUNL-01