BREEDING ACTIVITY AND CHORUS TENURE OF 2 NEOTROPICAL HYLID FROGS

Tropical frog species exhibit a wide variety of reproductive strategie s, including opportunistic and continuous breeding. Opportunistic bree ders are active for only a few nights at a time but usually call vigor ously for many hours. More continuous breeders are active on more nigh ts but often have more moderate calling rates. In this investigation, I studied the calling activity of two tropical hylids, Scinax rubra, a n opportunistic breeder, and Scinax boulengeri, a more continuous bree der. Males of S. rubra were present in choruses for one night on avera ge and chorus activity was significantly correlated with rainfall. On the other hand, males of S. boulengeri were observed on as many as 51 nights during the breeding season, and choruses were active on all cen sus nights, regardless of rainfall. Overall, chorus tenure was quite b rief in S. rubra but relatively more prolonged in S. boulengeri. In ad dition, males of S. boulengeri suffered gradual deterioration in body condition. These patterns suggest a tradeoff between energy investment in calling on a single night and number of nights of calling activity . Thus, I interpreted differences between the two species in chorus te nure in light of differences in morphological and biochemical characte ristics of muscles involved in call production.