Airdate: Sep 20, 1999
Scientist: Scott Weidensaul
BIRD MIGRATION- Navigation
Traveling without the guidance of their elders, how do young birds navigate their migratory routes?
It's migration season for billions of birds in the Western Hemisphere. Most birds migrate with others of their same age group- meaning that younger birds will travel long distances without the guidance of older birds who have made the trip before. So how do they find their way? I'm Jim Metzner, and this is the Pulse of the Planet, presented by the American Museum of Natural History.
"We have a fairly good idea of how birds find their way, how they orient themselves in the landscape."
Scott Weidensaul is the author of Living on the Wind, a book about bird migration.
"Most of the small birds migrate after dark. And these birds rely to a very heavy degree on celestial navigation. Now they're not looking at the star patterns; they're just aware of that rotation that tells them where north is. They also can tap into the earth's very faint magnetic field. So they have all of these orientation clues that tell them where north is. But knowing where north is doesn't do you any good unless you have a map to go with it, and science has had a much harder time figuring out what kind of map sense birds have that allow them to navigate across the land. And it appears that, in part, it's a learned process. Young birds are much more likely to show up in the wrong place than adults are. It also appears that birds use what's called a time distance program. Birds will have an urge to fly in a certain direction for a certain number of days, and then they may change their orientation and fly in a different direction for a certain number of days. It's all hormonal, it's completely an unconscious decision, and yet, you know, you can have a bird that will fly down the east coast, hang a right, go along the Gulf coast, hang a left, go down through Mexico and Central America and follow this extremely complicated course, even though it has no idea where it's going."
Pulse of the Planet is presented by the American Museum of Natural History. Additional funding for this series has been provided by the National Science Foundation. I'm Jim Metzner.