The language of bats

A research team lead by Silke Voigt-Heucke from the Leibniz Institute for Zoo and Wildlife Research in Berlin recently showed that bats can identify members of their own species and even members of their own social group from echolocation calls. The researchers tested how lesser bulldog bats (Noctilio albiventris) respond to the playback of echolocation calls of familiar and unfamiliar bats of their own and other species. Bats responded to the echolocation calls with a complex repertoire of social behaviour, for example by stretching out their wings and exposing their smelly subaxillary glands in their armpits, which allows potent pheromones to be released.

Bats reacted much more frequently to calls from unknown bats than to known bats from their same species and responded least of all to the calls of other bat species. Even more surprising is that when bats heard echolocation calls of their own species, they called back with a special vocalization that carried an individual acoustical signature. The researchers think that these calls represent some form of greeting such as "Hello, it's me."

The researchers conclude that bat echolocation conveys social information and thus is not only used for orientation but also communication in bats. Bats seem to use a language of their own, in frequency ranges not audible to humans.

The research was conducted in cooperation with the Max-Planck Institute for Ornithology, the University of Vienna and the University of Bern and was recently published in Animal Behaviour.