Gray Tree Frogs
Gray tree frog males have a mating call that is a string of 20–40 pulses per call. These frogs produce 5–15 calls per minute. There is a trade-off in call duration and repetition. The longer the call, the fewer that are made each minute.
Tree frog females prefer a male with shorter but complex calls, as a rapidly robust croak indicates a quick mind. Sensory bias may come into play: preferring a trait which is not necessarily an indication of fitness but instead a preference that is an inherited disposition.