for National Geographic News
Vampire bats are the only mammals whose diet consists exclusively of blood, and when they find a source they like, they come back for more, feeding on the same individual on consecutive nights.
Now researchers have figured out how they do it: The bats can hear you breathing.
Bats are known to have a well-developed sense of smell, as well as organs that can detect the infrared radiation emitted by warm-blooded animals. (Get fast facts about vampire bats.)
But Lutz Wiegrebe, a neurobiologist at Ludwig-Maximilians University in Munich, Germany, and a colleague have found that bats are also good listeners.
Vampire bats have brain cells that are stimulated exclusively by breathing sounds, the researchers found.
Wiegrebe and study co-author Udo Groger suggest that listening is an important element in bats' prey selection. Their report appears in the June 22 issue of the journal BMC Biology.
The researchers trained vampire bats to discriminate between three sequences of breathing sounds recorded from three different human subjects.
The scientists then randomly interspersed additional breathing sounds recorded from the same three individuals and let the bats listen.
The bats were able to figure out which individuals produced the new sounds.
Human subjects were unable to make the same distinctions among the recordings.
This led the researchers to believe that the bats are able to hear and remember the unique ultrasonic components of an individual's breathing sounds.
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