Tree-hole frogs exploit resonance effects

These anurans know a trick or two when it comes to the romantic powers of song.

Abstract

Animal mating calls that exert a comparatively high sound pressure propagate over greater distances and generally have greater attractive power^1,2. Here we show that calling male Bornean tree-hole frogs (Metaphrynella sundana) actively exploit the acoustic properties of cavities in tree trunks that are partially filled with water and which are primarily used as egg-deposition sites. By tuning their vocalizations to the resonant frequency of the hole, which varies with the amount of water that it contains, these frogs enhance their chances of attracting females.