Lmimicry is a marvel of nature. In different branches of the tree of life, species imitate others, with astonishing fidelity. What purpose ? The great Charles Darwin stumbled upon this mystery. Two of his students, Henry Bates and Fritz Müller, solved it and revealed that through this meticulous work of copying, evolution allows one of the two species, sometimes both, to better ward off predators. The world of butterflies is full of such phenomena. But he is not alone: the harmless scarlet king snake protects itself by imitating the red and black stripes of the fearsome harlequin snake.
When it comes to wonders, the group of bats, and its approximately 1,400 species, never ceases to dazzle us. The only mammal with an active flight, expert in echolocation, the animal has an exceptional longevity compared to its size (up to 38 years) and a unique immune system that allows it to coexist with many viruses – the Covid-19 pandemic has reminded us of this.
The relationship between these two enchantments? No. Except that in the review Current Biology May 9, an Italian team announces that greater bats, a common species in Europe, could escape owls by imitating the buzzing of a hornet. A singular example of mimicry. Firstly because the known cases of this form of evolutionary adaptation are overwhelmingly visual, almost never sound. In mammals, it would even be the first time. As for a mammal copying an insect to escape a bird, such a threesome seemed downright unlikely.
The idea, however, had been floating around in Danilo Russo’s head for more than twenty years. The ecologist from the Federico-II University of Naples was then undertaking a field study in southern Italy and was surprised to hear a buzzing “wasp or hornet” when catching bats. A cry of fear? An alert for congeners? The researcher left the question fallow, before taking it up again two decades later.
The team started by comparing the amazing buzz to that of different insects. The software responsible for the analysis observed a strong proximity to the sound of honey bees and European hornets. Above all, by modifying the parameters in order to simulate the sound perceived not by humans but by birds, the similarity became almost perfect.
The scientists then conducted playback experiments on sixteen owls, eight from captivity, eight taken from the wild. Each group was made up half of owls, half of owls. To all the birds, they proposed three sounds: the “bzzz” of a chiroptera, that of a hornet and an ordinary bat sound. All the owls approached the speaker passing the third, but moved away from the first two. The movement was particularly marked in wild birds, the most likely to have encountered hornets.
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