• picture
  • picture
PRI's Environmental News Magazine

BirdNote® Navigating by the Earth’s Magnetic Field

Air Date: Week of March 2, 2012

stream/download this segment as an MP3 file

A Bobolink in flight. (Photo: © Paul Higgins)

Modern technology has made it easy for us humans to get around. All we need to do is plug in our coordinates to a GPS, and we’re good to go. But, as BirdNote®’s Michael Stein reports, migrating birds have some unusual ways of charting their flight path.

Transcript

GELLERMAN: It's Living on Earth, I'm Bruce Gellerman.

[BIRD NOTE® THEME]

GELLERMAN: Getting around these days is easy to do. Just tap in your destination on the old GPS, and you're good to go. Migratory birds, on the other hand, have other ways of finding their way, as BirdNote®’s Michael Stein reports.

[BOBOLINKS SINGING AND CALLING]

STEIN: How do birds navigate? They steer by landmarks and by the sun and stars. A keen sense of smell helps some birds chart their course. And, it turns out, migrating birds also find their way by responding to the magnetic field of the earth.

[BOBOLINKS SINGING AND CALLING]

STEIN: These bobolinks we’re hearing orient themselves to Earth’s magnetic north with the help of iron-rich magnetic crystals inside their upper beaks. Homing pigeons also carry these magnetoreceptors, as do robins and other birds.

[WHINNY OF AMERICAN ROBIN]

STEIN: But that’s not the only way birds use the earth’s magnetic field to help them on their way. Light hitting a specific protein in a bird’s eye may trigger a chemical reaction that varies depending on the direction of the earth’s magnetic field. And “birds may actually see Earth’s magnetic field in the form of changing dark areas across one eye.”


Bobolink © Tom Grey.jpg (Photo: © Tom Grey)

[BOBOLINKS CALLING]

STEIN: This sensitivity explains why night-flying birds need to recalibrate their magnetic sense every day by the light of the setting sun. In an experiment in central Illinois, 18 thrushes were fitted with radio transmitters and exposed to a misaligned magnetic field. When released after dark, the birds headed west. Birds not exposed to the false geomagnetic field headed north. On subsequent days, however, the misdirected birds reoriented themselves to follow their true course.

[BOBOLINKS CALLING]

STEIN: I’m Michael Stein.

GELELRMAN: To see some Bobolink photos, point your compass to our website LOE dot org.

 

Links

Bird sounds provided by The Macaulay Library of Natural Sounds at the Cornell Lab of Ornithology, Ithaca, New York. Bobolink song and calls recorded by D.S.Herr; whinny of American Robin recorded by G.A. Keller; and song of Bobolink recorded by A.A. Allen.

BirdNote® Navigating by the Earth’s Magnetic Field – New Discoveries was written by Todd Peterson.

“Masters of Magnetism” Preview. Ed Young. NewScientist. 27 November 2010.

“The Compass Within” Preview. Davide Castelvecchi, Scientific American. January 2012.

 

Living on Earth wants to hear from you!

P.O. Box 990007
Prudential Station
Boston, MA, USA 02199
Telephone: 1-617-287-4121
E-mail: comments@loe.org

Donate to Living on Earth!
Living on Earth is an independent media program and relies entirely on contributions from listeners and institutions supporting public service. Please donate now to preserve an independent environmental voice.

Newsletter
Living on Earth offers a weekly delivery of the show's rundown to your mailbox. Sign up for our newsletter today!

Major funding for Living on Earth is provided by the National Science Foundation.

Committed to healthy food, healthy people, a healthy planet, and healthy business.

Innovating to make the world a better, more sustainable place to live.

Kendeda Fund, furthering the values that contribute to a healthy planet.

The Grantham Foundation for the Protection of the Environment: Committed to protecting and improving the health of the global environment.

Contribute to Living on Earth and receive, as our gift to you, an archival print of one of Mark Seth Lender's extraordinary hummingbird photographs. Follow the link to see Mark's current collection of photographs.