In order to attract females, male tungara frogs use two kinks of calls: a whine and a whine-chuck. A. Túngara frogs generally use simple calls when they wish to attract a mate, and complex calls when they wish to avoid predation. B. The hypothesis that whine calls are used to save energy when males are not in immediate competition with each other has been disproved by showing that chuck calls do not require more energy. C. Most males gather in groups of several hundreds when calling because the rate of predation from bats is so high in small groups. D. Two hypotheses have been put forward about why females and frog-eating bats are more attracted to males using whine-chuck calls. E. Túngara females overwhelmingly favor the whine-chuck call used by the males, but so do certain bats that prey upon túngara frogs. F. Male túngara frogs use the whine-chuck call in large groups, where their risk of predation is lower, and the whine call in small groups, where their risk is higher.