Research on bats gives clue for new navigation tools
Dec. 12, 2006
KALAMAZOO--An international group of scientists, including one from Western Michigan University, has solved the mystery of how bats navigate long distances in the dark, and the discovery could influence the development of future technology.
The team's findings were reported in the Dec. 7 issue of Nature.
WMU's Dr. Maarten Vonhof, assistant professor of biological sciences, and his four research colleagues say big brown bats, Eptesicus fuscus, depend on the Earth's magnetic field to stay on course in the night sky. Their discovery has implications not only for how habitat changes can affect the migration of bats, but also for the possibility that this navigation technique can be mimicked by technology.
The team's paper noted that the discovery adds to knowledge of "the impressive array of sensory abilities" bats use to steer in the dark. The study was immediately picked up in reports by the BBC, National Geographic and National Public Radio.
Over short distances, bats locate prey and avoid obstacles by bouncing sound waves from objects and registering echoes in a manner comparable to sonar aboard a submarine. However, this form of navigation, called echolocation, is less useful over distances longer than 30 meters, according to Vonhof.
To navigate longer distances, some creatures such as homing pigeons, migratory birds, newts and turtles are thought to use magnetic fields for orientation. To test bats' reliance on the magnetic field for navigation, the researchers chose the big brown bat--a species found throughout the United States and Canada.
Some bats were exposed to an artificial magnetic field pointing east or west relative to the Earth's magnetic north, while other bats were not exposed. The creatures were equipped with radio transmitters, transported 20 kilometers north, and their flight home tracked by the researchers using a small aircraft.
The team found the group exposed to the artificial fields flew in the wrong direction, although some of the deflected bats were able to reorient themselves, shift their direction and head home. The bats that were not exposed to artificial changes in the Earth's magnetic field returned in the direction of their roost.
"From a biological perspective, it's extremely important to find out what helps them survive," says Vonhof. "From a conservation perspective, we need to have a better understanding of how environmental changes might affect their migration."
Also, just as the development of the submarine was aided by discoveries in animal orientation, understanding how animals use the Earth's magnetic field to navigate might help with future technological developments.
"It teaches about another way to navigate. It's another contribution to the whole field of aerial navigation in general," says Vonhof.
Researchers who joined him in the study include Richard A. Holland of Princeton University and the University of Leeds, Martin Wikelski also of Princeton University, Kasper Thorup of the University of Copenhagen and William W. Cochran with the Illinois Natural History Survey.
For more information about the research, contact Dr. Maarten Vonhof at firstname.lastname@example.org or (269) 387-5626.
Media contact: Deanne Molinari, (269) 387-8400, email@example.com