Male tungara frogs add distinctive clicking notes called chucks to their mating calls.
The basic tungara frog call is a whine. A male may append one or more chucks, producing a complex sound that females generally find more attractive than a whine alone. The chuck is made with the mouth and vocal system, while the vocal sac helps project the overall call.
This elaborate signal has a cost. Frog-eating bats can detect and locate calling males, so a more attractive call may also increase predation risk. The trade-off makes tungara frogs a classic example of how sexual selection and natural selection can pull animal signals in opposite directions.
Chucks are not the same as the frog’s entire call. The whine is the basic component, and chucks are additional notes. The spelling “túngara” refers to the common name of Physalaemus pustulosus, a small frog native to parts of Central and northern South America.