Creating a buzz: These bats pretend to be bees to seem more dangerous

It’s the first known case of a mammal mimicking an insect, scientists say

Sometimes you have to fake it until you make it.

Well, at least for some animals, you have to pretend to be scary and dangerous until you’re no longer on the verge of being eaten.

Pretending to be an animal much more dangerous than yourself is what biologists call “Batesian mimicry” – which scientists have now documented in a species of European bat that buzzes like a hornet.

Their report, published on Monday 9 May in Current Biology, notes that this is the first evidence of a mammal mimicking the sound of a more dangerous animal.

When researchers studying greater mouse-eared bats handled the animals, they noticed something strange — the bats seemed to buzz like hornets or bees. They theorised that the bats could be mimicking insects in an attempt to ward off potential predators.

To test this idea, they compared the soundwaves of the bat buzz to the sound of a rather unpleasant insect: the stinging, buzzing European hornet.

They also played buzzes from bats, hornets and honeybees over a speaker to some barn owls and tawny owls — two potential bat predators — to see how the birds would respond, in addition to a non-buzzing bat sound as a control.

When many of the birds heard the non-buzzing bat sound, they moved closer to the speaker — which could mean that the birds were interested in the potential for food, the researchers speculate via a statement.

But when the researchers played the buzzing — of bees, hornets and the bats alike — many of the owls moved away from the speaker.

The different responses to the buzzing sounds and the non-buzzing bat sound seemed to be more pronounced in wild-caught owls, who could have encountered bats and hornets, than in captive-bred owls who wouldn’t have had that experience, the paper notes.

When the team looked at the shape of the soundwaves, the bat buzzes and hornet buzzes were similar within the range of sounds audible to the owls.

It’s not exactly clear why the owls might avoid the buzzing, the researchers note in their statement — maybe the owls are afraid of getting stung, or maybe the birds try to avoid dangerous insects in general, for example.

But the paper notes that these results offer “strong support” for the “first documented example of mimicry between mammals and insects”. It’s also, they note, one of the few examples of an animal mimicking another animal’s sounds.

Other types of Batesian mimicry are well-documented. For example, some non-toxic frogs and butterflies have evolved to copy the shape and colours of more toxic species — and some moths have even evolved to match the colouration of more threatening hornets.