The rise and fall of a population of Hyla boans: Reproduction in a neotropical gladiator frog

A population of Hyla beans was studied in central Amazonian rainforest duri ng 15 years. The species differs from other intensively-studied gladiator f rogs, Hyla rosenbergi and Hyla faber, in that males reach larger sizes than females, most reproduction is in the dry season, males call mainly from tr ees and rarely from nest basins, and most nest basins have aquatic connecti ons to streams. Many adults (15% of females, 21% of males) were captured ov er more than one breeding season, and some were captured over five breeding seasons. Sizes of juveniles, and growth of one individual, indicate that m ales require at least two years between hatching and entering the breeding population. Daily calling was bimodal, with peaks after dusk and before daw n. Rainfall reduced calling activity during the peak of the breeding season . The population at the site declined to zero density after nine years of s tudy and the site still had not been recolonized six years later. The expon ential rate of decline of the population (-0.58) was more than three times the exponential rate of increase (0.15) at the beginning of the study.