These bats deter predators by buzzing like hornets

Date:
May 9, 2022
Source:
Cell Press
Summary:
In Batesian mimicry, a harmless species imitates a more dangerous
one in an evolutionary 'ruse' that affords the mimic protection
from would-be predators. Now, researchers have discovered the first
case of acoustic Batesian mimicry in mammals and one of very few
documented in any species: greater mouse-eared bats imitate the
buzzing sound of a stinging insect to discourage predatory owls
from eating them.



FULL STORY ==========================================================================
In Batesian mimicry, a harmless species imitates a more dangerous one in
an evolutionary "ruse" that affords the mimic protection from would-be predators.

Now, researchers reporting in Current Biology on May 9, 2022, have
discovered the first case of acoustic Batesian mimicry in mammals and
one of very few documented in any species: greater mouse-eared bats
imitate the buzzing sound of a stinging insect to discourage predatory
owls from eating them.


==========================================================================
"In Batesian mimicry, a non-armed species imitates an armed one to
deter predators," said Danilo Russo of Universita` degli Studi di Napoli Federico II in Portici, Italy. "Imagine a bat that has been seized but
not killed by the predator. Buzzing might deceive the predator for a
fraction of a second - - enough to fly away." Russo made the discovery
while conducting field research in which he frequently caught the bats
in mist-netting operations. "When we handled the bats to take them out of
the net or process them, they invariably buzzed like wasps," Russo says.

They recognized the buzzing as some sort of unusual distress call. They
thought there might be different reasons the bats made the sound. Perhaps
it could send a warning to others of its species or deter predators. Russo
and team put the idea aside and continued along with other research
questions. Years later, they decided it was time to design a careful
experiment to test their ideas about that buzzing.

In their studies, they first looked at the acoustic similarity between
buzzing sounds of the bats and stinging social hymenopteran insects. Next,
they played those sounds back to captive owls to see how they would react.

Different owls reacted in variable ways, likely depending on their
prior experiences. Nevertheless, they consistently reacted to insect
and bat buzzes by moving farther away from the speaker. In contrast,
the sound of potential prey got them to move closer. The researchers say
the findings provide the first example of interspecific mimicry between
mammals and insects as well as one of few examples of acoustic mimicry.

Interestingly, their analysis of the sounds revealed that the similarity between buzzes broadcast by hornets and bats was most evident only
once acoustic parameters that the owls can't hear were excluded from
the analysis.

In other words, Russo explains, the buzzing sounds are even more similar
when heard the way owls hear them.

Do owls avoid that buzzing sound because they've been stung before? Russo
says that stinging insects likely do sting owls, but they don't have
the data to prove it. There is other evidence that birds avoid such
potentially noxious insects, however. For example, when hornets move
into nest boxes or tree cavities, birds in general won't even explore
them and they certainly don't nest there.

Because the three study species in question all share many of the same
spaces, such as buildings, rock crevices, or caves, there is likely
to be plenty of opportunity for them to interact, according to the
researchers. Even so, they find this intricate relationship among
distantly related species intriguing.

"It is somewhat surprising that owls represent the evolutionary
pressure shaping acoustic behavior in bats in response to unpleasant experiences owls have with stinging insects," says Russo. "It is just
one of the endless examples of the beauty of evolutionary processes!"
Russo notes that there are many other vertebrate species that also
buzz when disturbed and hundreds of bat species, some of which may use
similar strategies. They hope to look for these interesting dynamics
within other interacting groups in future studies.


========================================================================== Story Source: Materials provided by Cell_Press. Note: Content may be
edited for style and length.


========================================================================== Journal Reference:
1. Leonardo Ancillotto, Donatella Pafundi, Federico Cappa, Gloriana
Chaverri, Marco Gamba, Rita Cervo, Danilo Russo. Bats mimic
hymenopteran insect sounds to deter predators. Current Biology,
2022; 32 (9): R408 DOI: 10.1016/j.cub.2022.03.052 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/05/220509112030.htm

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