NOCTURNAL BIRD MIGRATION: Monitoring

When birds fly south for the winter, they often travel by night, which makes it difficult for scientists to track the numbers of different species. But it may be possible to monitor the bird migration using sound. I’m Jim Metzner and this is the Pulse of the Planet, presented by the American Museum of Natural History.

“These insectlike calls are coming from up in the sky and these are birds giving these calls to work out their flight spacing so that they don’t crash into one another and maybe to keep in contact with other buddies that they’re traveling along with.”

Bill Evans is a research associate at the Cornell Laboratory of Ornithology. He tells us that these nighttime airborne chirps are quite different from the songs these same birds sing during the day when we usually hear them. Mr. Evans has spent the past twelve years learning to identify each species’ unique nocturnal call as a means to monitor migrating bird populations.

“Previously we’ve really only been able to see these mass migrations, well the best way is with radar. And on certain nights you look at a radar screen and you see all these slow moving little dots going by. What the frustrating thing has been, what we haven’t known, the species composition.”

But we could learn the species composition by listening for them at night with sensitive recording equipment.

“In one of my big dreams is to set up a line of recording stations from, say, Cape May, New Jersey to central Colorado. To sort of form an acoustic net, so that the songbird migrations that are coming down out of Canada and Northern US, we can tabulate these calls and sort of form another way to get an estimate of species populations and migration routes.”

More on nocturnal bird migration in future programs. Pulse of the Planet is presented by the American Museum of Natural History. I’m Jim Metzner.

NOCTURNAL BIRD MIGRATION: Monitoring

By learning the unique nocturnal calls of migrating birds, scientists are able to monitor populations.
Air Date:10/09/1997
Scientist:
Transcript:

When birds fly south for the winter, they often travel by night, which makes it difficult for scientists to track the numbers of different species. But it may be possible to monitor the bird migration using sound. I'm Jim Metzner and this is the Pulse of the Planet, presented by the American Museum of Natural History.

"These insectlike calls are coming from up in the sky and these are birds giving these calls to work out their flight spacing so that they don't crash into one another and maybe to keep in contact with other buddies that they're traveling along with."

Bill Evans is a research associate at the Cornell Laboratory of Ornithology. He tells us that these nighttime airborne chirps are quite different from the songs these same birds sing during the day when we usually hear them. Mr. Evans has spent the past twelve years learning to identify each species' unique nocturnal call as a means to monitor migrating bird populations.

"Previously we've really only been able to see these mass migrations, well the best way is with radar. And on certain nights you look at a radar screen and you see all these slow moving little dots going by. What the frustrating thing has been, what we haven't known, the species composition."

But we could learn the species composition by listening for them at night with sensitive recording equipment.

"In one of my big dreams is to set up a line of recording stations from, say, Cape May, New Jersey to central Colorado. To sort of form an acoustic net, so that the songbird migrations that are coming down out of Canada and Northern US, we can tabulate these calls and sort of form another way to get an estimate of species populations and migration routes."

More on nocturnal bird migration in future programs. Pulse of the Planet is presented by the American Museum of Natural History. I'm Jim Metzner.