Sonar spots the puffing throat chamber of the Central American amphibians
Bellowing male túngara frogs make easy prey for fringe-lipped bats thanks to echolocation, scientists report August 27 in the Journal of Experimental Biology. The bats’ sonar spies the Central American amphibians’ ballooning vocal sac, turning a sexual display into an invitation for lunch.
When inflated, the vocal sac nearly matches the full body size of the male túngara (Physalaemus pustulosus). Both the sac’s girth and a frog’s love song enchant female mates. Fringe-lipped bats (Trachops cirrhosus) hunt the males, but scientists wondered how senses besides hearing guide the pursuit.
To investigate, researchers placed 10 wild fringe-lipped bats into netted enclosures with two lifelike rubber imitations of male túngaras, dubbed robofrogs. Both robofrogs played mating calls, but only one had a billowing vocal sac. The other’s sac remained deflated. The researchers observed that the bats always attacked or hovered