Resource use and coexistence of two syntopic hylid frogs (Anura, Hylidae)

Abstract

The objectives of this study were to measure and compare niche breadth and overlap of males of Hyla nana Boulenger, 1889 and Hyla sanborni Schmidt, 1944 in three neighboring ponds. The measured niche dimensions were seasonal occurrence, call site, and diet. The reproductive season of H. sanborni was longer in permanent ponds, whereas H. nana had a longer reproductive season in the temporary pond. Call site characteristics were similar for both species, however H. sanborni called from higher perches than H. nana. Diptera (Nematocera) were the most consumed item by both species in the three ponds but, in general, H. nana ingested larger prey than H. sanborni. For both species, the consumption of prey types was correlated with the availability in the environment. The multidimensional overlap between H. nana and H. sanborni was higher in the permanent ponds than the temporary pond, in which H. sanborni was rare. These species differed in abundance among ponds, consumed prey of different sizes, and probably fed in different time periods. Moreover, the data obtained suggest that structural differences in the ponds may modify the dynamics of resource partitioning between the two species. Beside the great overlap found in the major niche dimensions analyzed the detected differences may be great enough to allow their coexistence.