Variable Responses to Rainfall by Breeding Tungara Frogs

Though many amphibians breed in response to rainfall, rainfall can create substantial risks as well as benefits. For species that breed in ephemeral ponds and puddles, heavy rainfall can create many ‘‘false’’ ponds that quickly desiccate, particularly in wet years. As a result, nightly responses to rainfall may vary depending on seasonal or yearly rainfall. I used two years of data and previous studies to demonstrate variation in response to rainfall by breeding Tungara Frogs (Physalaemus pustulosus) on Barro Colorado Island, Panama. In 1997, an unusually dry year, breeding tungara frogs were far more abundant on wet nights than on dry nights. In 1998, an average year for rainfall, tungara frogs exhibited no significant response to rainfall and even a trend toward greater abundance on dry nights. In addition, female frogs were more sensitive to the effects of rainfall than were males. As a result, mating system parameters were highly dependent on both nightly and yearly rainfall.