Bats use echolocation not only to navigate, but also to spot and capture male frogs that are in the act of courting.

Many male frogs inflate their vocal sacs while sending out calls to attract potential mates. Wouter Halfwerk at the Smithsonian Tropical Research Institute in Balboa, Panama, and his team exposed wild-caught fringe-lipped bats (Trachops cirrhosus) to robotic models of the male túngara frog (Physalaemus pustulosus) that either puffed out a vocal sac (pictured) in time with a call or just emitted the call.

Credit: Ryan Taylor

They found that all the bats preferentially attacked the model that inflated its sac in sync with the call. The bats used echolocation to detect the 'frogs' from 3–5 metres away, whereas female frogs use vision to assess the male's vocal sac. The results suggest that sexual and natural selection can act on the same trait through different senses.

J. Exp. Biol. 217, 3038–3044 (2014)