Bats may recognize voices of friends they hang out with.
Hanna Kastein from the University of Veterinary Medicine in Hannover, Germany, and her colleagues chose bats for their study as they are social mammals whose aerial lifestyle favours the use of acoustic cues for both orientation and communication.
Body contacts among the social groups in the False Vampire bat, Megaderma lyra, suggests individualized relationships.
The researchers suggested that the ability to recognize individuals by sound could govern the reunion of groups at night roosts.
When isolated bats are observed, they emit calls that result in the bat being joined by members of its usual night roosting group, giving weight to the belief that others must recognize his call.
The authors used two groups of bats for their study.
The groups were kept in separate flight rooms and observed over a minimum of two months. The researchers observed the established body-contact partners and separated bats from their respective groups to evoke emission of contact calls, which they recorded.
These calls were then played back to bats that were either body-contact partners, no body-contact partners or unknown bats from another group.
The behaviour of the experimental bat was measured using the turning reaction of it's body towards the loudspeaker emitting the call.
The researchers found that the bats reacted to all single contact calls by turning towards the loudspeaker whether it was from a body-contact, no body-contact or unknown bat, which showed that they did not have a clear preference for calls from body-contact partners under these circumstances.
The strong response to all the calls could be caused by the high attractiveness of any contact call to temporarily isolated bats.
However, in the set of experiments where bats were repeatedly presented with a call from a known bat until they gave no reaction to the sound and then presented with a different call, they showed a stronger turning response to other partners from their social group compared to a different call from the previously presented bat.
This would suggest that the bats make an individual evaluation of the voice.
The study has been published in the Springer journal Animal Cognition. ( ANI )
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