Call Of Male Bats That Warn Other Bats From Snagging Their Dinner Identified
Bats are not blind, in fact they can see as well as you and me. But they use echolocation to navigate and forage in the dark. By emitting a series of high frequency sounds they can identify obstacles and insect prey. But now a team of scientists have discovered that bats use another type of call that tells their potential competition to stay away from the prey they have caught, according to a press release.
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Genevieve Spanjer Wright, a biology research associate from the University of Maryland, and her associates found that male big brown bats can produce a special sound, called a "frequency-modulated bout" (FMB). This sound is emitted by the bat as a warning to other bats to keep away from the bug it has caught. This is the first time that FMB has been identified in hunting male big, brown bats and this report will be published on March 31 issue of the Cell Press journal Current Biology. This discovery is important in understanding how vocal social communication facilitates interaction among nocturnal foraging animals.
For the research, the biologists recorded calls of two bats flying and foraging together. When they examined these audio recordings along with videos of the male and female bats flight paths and calls as they flew alone and in groups foraging for tethered mealworms, they discovered the unique call they later named FMB.
FMB is an ultrasonic social call and is different from echolocation calls in that it is used exclusively for social interactions. The FMB is unique to each bat and is a sequence of three to four sounds, longer in duration and lower in frequency than the typical echolocation pulses that big brown bats use to navigate. It is often followed by short buzz like calls.
The researchers found that once the bat has emitted the FMB, other bats stayed clear of its path and moved away from the prey, thus giving the caller a higher chance of catching the prey."When two males flew together in a trial, it was not uncommon for each bat to emit FMBs," says Wright. "We found that the bat emitting the greatest number of FMBs was more likely to capture the mealworm."
Generally animals hunting in groups give out sounds to invite others to share their prey but bats emit FMB to repel other bats."Despite decades of study, many things about common bat behaviors such as foraging remain mysterious," says Wright. "We were able to study a social call that is likely occurring thousands of times a night all over North America during the summer months, yet had not been described or studied before now."
An interesting discovery made by the researchers is that FMB is emitted only by big brown male bats, possibly to show their territorial dominance and ward of competition. Male bats have a tendency to forage alone or in small groups with other males and do not necessarily forage with familiar bats. FMB is not emitted by females since they form close associations with their roost mates and may forage near familiar individuals.
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