ESCALATED AGGRESSIVE-BEHAVIOR AND FACULTATIVE PARENTAL CARE IN THE NEST-BUILDING GLADIATOR FROG, HYLA FABER

Agonistic encounters and facultative parental care in Hyla faber were observed in two localities in southeastern Brazil. Maximum male densit y was 0.9 and 3.3 males/m(2) in Campinas and Ribeirao Branco, respecti vely. Aggression was escalated and the highly variable aggressive call s were specific to each phase of the encounter. The last, more aggress ive phases rarely occurred in Campinas; in Ribeirao Branco they occurr ed frequently. Male parental care (egg attendance) was common in Ribei rao Branco while it was never observed in Campinas. Egg attendance las ted one to two nights and was observed only during high male density. The main benefit of egg attendance seemed to be avoiding nest intrusio n by other males (sunken eggs and/or embryos invariably die). Males ma y build additional nests during egg attendance, but attending males di d not attract females (they did not call).