How do bats deceive predators like birds?
In the first documented case of its kind in a mammal, a bat sounds like an insect to scare off bat-eating birds.
Resembling something you’re not can be a good way for a potential prey species to deceive a predator. Some harmless, palatable insects mimic distasteful ones to deter hungry birds, for example, often through conspicuous warning colouration that gives a false impression of nastiness.
Known as ‘Batesian mimicry’ after the Victorian naturalist who discovered it in Amazonian butterflies, the effect has fascinated evolutionary scientists, from Charles Darwin onwards, for 160 years.
Most examples involve visible overlap between creatures that are very different in terms of food potential.
Deceptive mimicry using sound is noticed much less often. Now a team of researchers, led by Danilo Russo from Università degli Studi di Napoli Federico II in Italy, has found what is claimed to be ‘acoustic mimicry’ in a mammal.
The study was developed after Russo noticed that greater mouse-eared bats (Myotis myotis) made loud buzzing noises when handled, akin to those made by hornets and wasps.
This was confirmed by computer-based analysis of greater mouse-eared bat distress calls and those from several stinging insects.
Russo’s team then played recordings of both hornets and bats to captive owls, and filmed their reactions. When the birds heard calls recorded from relaxed bats, they often approached the speakers, an effect strongest in owls that had spent some time in the wild.
But the owls moved away from recordings of both distressed bats and hornets, suggesting that by mimicking a stinging insect, greater mouse-ears could deter predators.
The researchers reckon that there’s now fresh scope to explore the evolutionary meaning of sonic mimicry of insects.
Sounds like it would be music to Darwin’s ears.
Main image: The greater mouse-eared bat feeds on larger flying and ground insects © Theo Douma/Agami/Alamy
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