Bats in Costa Rica using leaves for hearing

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There are many examples in nature of animals using objects to boost their calls, but situations where animals use objects to amplify sound are not nearly as frequent. Livescience reports on research showing how a social species of Costa Rican bats uses funneling leaves as a type of ear horn to hear other members of their group. The studies were carried out by researchers from Boston University and North Dakota State University (USA).

Spix’s disk-winged bats (Thyroptera tricolor) live in caves but roost in the unfurling leaves of certain plants during the day. They form groups of five or six individuals and tend to stay together for many years, a phenomenon that is quite rare in bats. They have a complex communication system involving a single-sound inquiry call that they emit when in flight to locate other bats in their roosting group. Members of their group then make response calls consisting of as many as 20 to 25 sounds. The difficulty the bats have is hearing the inquiry calls from large distances.

This is where the furled leaves come into play. The researchers used recorded calls and microphone recordings in the leaves to show that although amplification of outward-bound sound was minimal, incoming calls were amplified by up to 10 dB. This suggests that the bats deliberately nest in rounded leaves to increase their chances of hearing inquiry calls, so that they can send out a recognizable message to their fellow bats at the right time. According to the researchers, this acoustic effect may increase the distance at which flying bats are heard by an estimated 65 to 98 feet.

Source: Livescience.com

C.S.