Bats Use Magnetic "Compasses" to Navigate

"Some bats find their way home using an internal "compass" that senses Earth's magnetic field—similar to those believed to be used by migrating birds—researchers say.
Princeton University biologist Richard Holland in New Jersey and colleagues found that exposure to artificial magnetic fields confused such bats, causing them to fly in the wrong direction.
The finding, reported in tomorrow's issue of the journal Nature, is the first of its kind in bats and helps fill in a gap in scientists' understanding of how the animals navigate.
Night-flying bats are famous for their use of echolocation—bouncing sound waves off objects at fairly close range. Echolocation helps bats locate insect prey and steer around objects such as trees and buildings.
The new study suggests that a magnetic sense may help bats navigate over longer distances, such as when returning to nightly roost sites.
Holland theorizes that the bats, like some birds, also use sunset as a directional marker. This may let the animals fine-tune their internal compasses and adjust for the difference between magnetic and true north." (...)

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