Bats are climbing inside curled leaves and using them to amplify sound, marking the first time an animal has been observed using a tool to increase its vocalization range. A recent study has shown that Spix's disk-winged bat uses the shape of the leaves to boost the sound of both incoming and outgoing calls.
The tiny bats — so named for cute little suction disks on their wings — roost inside curled-up leaves. To identify the correct roosting spot, they call out: when that call is met by a chirped response, they know they've found home. The study, published by the Proceedings of the Royal Society, found that both call and response sounds were amplified by the shape of the leaves. Outgoing replies from roosting bats were faintly boosted by the leaves' trumpetlike effect; incoming calls from flying bats were significantly increased in power as sound waves were funneled down the leaves' lengths.
The study also found that both of these calls were so significantly distorted by their leaf modulation that roosting bats wouldn't be able to understand who was making the sound. Christine Dell'Amore explains that roosting bats instead "respond indiscriminately" to calls of their species. Response calls, Dell'Amore says, are "more acoustically complex," meaning that despite leaf distortion, enough information gets through for a calling bat to successfully find his friends.