Imitation is a widespread phenomenon in the animal kingdom.
Some caterpillars can be dangerous snakes. Young sooty sad tyrant, who lives in the Amazon, turns into poisonous larvae. In their evolution, hovercraft have adapted to resemble stinging and obnoxious wasps.
They are all examples of batesian mimicry, an evolutionary trick in which a relatively harmless animal takes on a more dangerous appearance in order to change the minds of predators.
However, to our knowledge this particular form of mimicry is almost always visible in nature and is generally only observed in insects, birds, and reptiles.
For the first time, a vocal form of mimicry is now observed in mammals. A study recently published in the journal current biology The long-eared bat, a common species in Europe, appears to mimic the sizzling of wasps to avoid being eaten by owls.
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“We found that a species of mammal mimics the sound of an insect to scare away birds of prey,” said Danilo Russo, lead author of the study and professor of ecology at the Federico II University of Naples in Naples. “This is an amazing evolutionary interaction between three species, which are evolutionarily distant from each other.”
rolling around …
pale bat (myotis myotis) is a common European bat species that preferably eats insects, especially beetles. It lives in colonies in woodland areas and on forest edges, roosting in caves most of the year, or in buildings during the summer. These bats often prey on birds of prey, including barn owls (Tito Albaand the brown owlAluminum Strix), especially if the mammal has left or returned to its place.
In 1999, Rousseau was working to create a library of tweeting sounds from European bat species, which animals use to “see” their environment using echolocation. He also collected data on the way certain types of bats communicate with each other. When he removed a small pale bat from his ‘mist net’ – a network so fine that it was indistinguishable from a bank of mist by birds (and bats) – and held it in his hand, Rousseau suddenly began shivering and emitting a loud bang.
“My first thought was that it sounded like humming hornets or hornets!” He says.
At first, the researchers suspected the noise was just a daily cry for help. But the sound was so distinctly that of an insect that, according to Rousseau, a hypothesis arose almost immediately. Years later, researchers decided to test this hypothesis: Could it be that bats consciously mimic the sound of wasps or bees?
Rousseau himself had once collected barn owl droppings at the entrance to a cave where these bats roosted. “The droppings have a lot of bat skulls in them,” he says, so it wasn’t impossible, he says, that the species “goed to a very, very hard evolutionary effort to deter owls.”
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On a high note
In their new study, Russo and colleagues first compared the sizzling sound of bats to four different types of hymenoptera, including honeybees (Apis melliferaEuropean hornetsvespa crabro† They analyzed the wavelength, frequency, duration and other properties of sounds and found that there were significant similarities in their structure.
Owls can pick up a wider range of sounds than humans. So the researchers slightly modified the sound characteristics of the humming sounds to get an impression of what an owl could hear, including by removing the highest notes. They realized that to owls’ sensitive ears, the hum of bats sounded more like the hum of insects than human hearing. “The agreement was especially evident when we omitted variables that owls don’t pick up,” Russo says.
The researchers then played two types of buzzing sounds over a set of loudspeakers: one from a bat buzzing and the other a bat call directed at owls of two different species (barn owls and brown owls), some in captivity and some in the wild. Starch.
When the owls heard the sounds of bats, they actually moved closer to the source of the sound, but in general the sound seemed to mainly irritate the birds and they tried to get away from the speakers, escape or at least go outside to find outside what was going on.
During the experiment, wild owls—who may have memories of times they were exposed to the flying insect—acted more fearfully and tried to escape than owls raised in captivity. Russo and his colleagues suspect that this can be explained by the fact that owls in captivity rarely, if ever, encounter a stinging insect. But so far, little scientific research has been done on whether owls are stings by bees, wasps and hornets, and how often they encounter these insects.
“The owls are sure it’s a serious confrontation,” Russo says. For this reason it is believed that this form of Batesian mimicry is probably a technique used by bats that were caught by owls and then tried to buy some time to escape while ringing.
As always in the case of these types of results, many questions remain.
According to Bruce Anderson, professor of entomology at Stellenbosch University in South Africa, future research – in the wild rather than in the lab, and with many owls – will need to confirm the findings to determine if it is truly the Batesian mimic. Another open question is whether the owls reacted anxiously to the volume of the bat’s ringing, as they likely did to any unfamiliar and loud noises. “We have to ask ourselves whether this is a case of imitation or an example of sensory preference,” Anderson says.
It is also unclear whether and to what extent owls fear hummingbirds, although various data indicate that birds generally do not nest in burrows where the insects have also settled. The researchers also want to answer the question of whether these buzzing sounds are unique to stinging insects or if they are also produced by other non-stinging insects. In addition, David Pfennig, a professor of biology at the University of North Carolina at Chapel Hill, who was not involved in the new research, can investigate whether owls that have been bitten are more fearful than owls that have not been squashed.
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While imitation is common and instances of Batesian imitation are well known, many aspects of it remain mysterious and awe-inspiring, according to Fennig. According to him, this is why results like those from the new experiment are important. “Cases of Batesian mimicry are the best examples of how remarkable adaptations emerge through natural selection, from interactions between groups of organisms that are not closely related at all,” Pfennig says. There are some other examples of vocal mimicry between different species, for example the way burrowing owls make a hissing sound like rattlesnakes. But mammals that mimic an insect seem to be an absolute novelty.
In the future, researchers wish to refine and expand their research.
“While it is always useful to confirm observations in the field, the results of our research were very straightforward,” Russo says. “It would be interesting to note similar strategies in other species.” More than 1,400 species of bats and a handful of other vertebrates make buzzing sounds when they feel threatened, so Rousseau thinks other animals are using the same trick.
Anastasia Helen Dalziel, an ornithologist and researcher at the University of Wollongong in Australia who was not involved in the new study, said the strategy of avoiding predators by making frightening noises may be prevalent among animals living in burrows or caves.
“What we know about imitation is largely due to studies of its visual transcription, but in principle mimicry can work with other sensory experiences as well,” Dalziel says. “It’s really cool that we now have a new example of vocal mimicry (…), because it pushes us to explore the phenomenon on a larger scale.”
This article was originally published in English at nationalgeographic.com