Hamburg  - Bats use "voice recognition" to find each other in caves and in the dark of night, according to German scientists, who say this has implications for the development of language among non-human species.

It has long been known that bats emit high-frequency calls to find their way in the dark and to find insect prey. This is called echo-location.

But according to the study by researchers from the University of Tuebingen and the University of Applied Sciences in Konstanz, the German researchers discovered that bats use echo-location for more than just spatial knowledge.

The flying mammals actually recognize each others' "voices" and respond to each other. The discovery may provide an explanation for the complex socialization systems of bat colonies.

"The finding that bats can recognize other bats within their own species based on their echo-location calls may therefore have some significant implications," the German researchers wrote in a report published in the Public Library of Science (PLoS) Computational Science.

The German scientists, Yossi Yovel, Mariana Laura Melcon, Matthias O. Franz, Annette Denzinger and Hans-Ulrich Schnitzler, said their findings show that the greater mouse-eared bat uses its echo-location skills not just to navigate, but to communicate.

"We used a direct paradigm to show that greater mouse-eared bats (Myotis myotis) can easily discriminate between individuals based on their echo-location calls and that they can generalize their knowledge to discriminate new individuals that they were not trained to recognize," the scientists wrote.

"We conclude that, despite their high variability, broadband bat echo-location calls contain individual-specific information that is sufficient for recognition. An analysis of the call spectra showed that formant-related features are suitable cues for individual recognition," they added.

The researchers first tested the ability of four bats to distinguish between the echo-location calls of other bats.

When they realised the bats could distinguish the "voices" of other bats, the German researchers then created a computer model that reproduces the recognition behaviour of the bats.

Study of the computer results and analysis of the model confirmed that the bats were indeed calling to each other.(dpa)