Scientists have discovered a clever mimicry trick used by some bats: they buzz like hornets when they think they are threatened by predators, giving the sonic impression that they are more dangerous than they are are actually.
This is the first time behavior like this has been recorded in mammals, but it has happened elsewhere in the animal kingdom – such as when moths’ wings are shaped to make the insect look like it’s actually a different, much more dangerous species. The technical term for this is Batesian mimicry.
The team behind the new bat study say their findings provide important insight into both evolutionary processes and how animals will try to defend themselves when cornered.
“In Batesian mimicry, an unarmed species mimics an armed species to deter predators,” says ecologist Danilo Russo, from the Università degli Studi di Napoli Federico II in Italy.
“Imagine a bat that was grabbed but not killed by the predator. The buzzing could fool the predator for a split second – enough to fly away.”
It was during fieldwork that Russo and his colleagues noticed larger mouse-eared bats (myotis myotis) making buzzing sounds whenever researchers handled animals caught in nets. It sounded like some sort of distress call, but it wasn’t until years later that work for this study began.
To confirm their intuition that the buzz is a type of Batesian mimicry, the researchers compared the strong similarities between the buzzes emitted by bats and social stinging hymenopteran insects (like wasps and bees).
They then played these sounds to certain bat-eating predators: wild owls and captive-bred owls. While the reactions varied – perhaps due to the birds’ previous experiences – there was also some general consistency with respect to the buzzing of insects and bats, and the standard non-buzzing sounds of bats. mouse.
“Owls consistently reacted to the buzzing of Hymenoptera and bats in the same way, increasing the distance from the speaker,” the researchers write in their published paper.
“As they approached the latter in response to the control stimulus, as expected from non-mimetic vocalization produced by potential prey.”
Owls that had not been bred in captivity showed the strongest adverse reaction to bat and insect buzzing, as they are likely more knowledgeable about potential damage than captive-bred owls.
Another notable finding: When the acoustics were analyzed to show only sounds that owls can hear, the similarities to insects were more pronounced.
It’s possible that this mimicry evolved due to the fact that bats and insects share many of the same spaces (including caves and crevices in rocks), but this type of acoustic mimicry is rare – and it is interesting to see bats borrowing from another species to recover from their predators.
“It’s somewhat surprising that owls represent the evolutionary pressure that shapes the acoustic behavior of bats in response to the unpleasant experiences owls have with biting insects,” Russo says.
“This is just one example of the beauty of evolutionary processes!”
The research has been published in Current biology.
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