Finding your way in the dark

Des chauves-souris
  • Des chauves-souris
  • Glossophage de Pallas (Glossophaga soricina)
  • Des chauves-souris
Finding your way in the dark

Three species of bat live in the Biodôme caves: the Jamaican fruit-eating bat, the Seba’s short-tailed bat and the Pallas’s long-tonged bat. Natives of Central America, the Gulf of Mexico, the Caribbean and upper South America, our three guests are fruit feeders, but don’t hesitate to eat pollen, nectar, and of course insects to supplement their diet.

Seeing with the nose

It’s been known for a long time that these small mammals use ultrasound to locate their prey and to avoid obstacles. That faculty even has a name, echolocation, and a parallel invented by man, sonar. Have you noticed the strange noses on the Biodôme bats? Have a look the next time you visit: it’s thanks to them if they see you! Those noses send out the ultrasound that bats create by vibrating their vocal cords.

Still, it was only very recently that researchers proved that bats can recognize and memorize places courtesy of that same system.

The question was worth asking. Because whereas our eyes can quickly distinguish a cavern from a cliff or a forest from a prairie, the same can’t be said for ears. Sound analysis produces highly unusual information compared to the data of the visual world that we’re used to.

Landscapes in ultrasound

A team of researchers therefore wanted to see if echolocation could produce a signature of places, as our eyes do. They created an artificial bat: an apparatus equipped with sonar, which they flew at the same height as our winged friends in different typical habitats for chiroptera, to use their little scientific name. And they came to realize that a computer was fully capable of recognizing each type of place – using nothing but ultrasound!

They also discovered that great accuracy was not needed in order to recognize the environment. After all, a forest without the details of each leaf is no less a forest. Thus, the researchers concluded, bats would not need to re-create a faithful tridimensional image of their surroundings to know where they happen to be. Finally, bats may be as short-sighted as flying moles, but they know exactly where they’re going!

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