Effects of previous experience on aggressive behavior in male gray treefrogs (Hyla versicolor)

Background/Question/Methods

Aggressive behavior has been studied intensively in animals because the factors involved in success in aggressive interactions may be major component of individual fitness. An individuals’ past experience could affect its behavior in future aggressive interactions. One particularly notable effect of previous experience is the observation that in many species, winners of previous contests are more likely to continue winning (winner effects) and losers of previous contests are more likely to continue losing (loser effects). We examined the effects of previous experience in aggressive interactions of the gray treefrog (Hyla versicolor). We tested 2 hypotheses: 1. That aggressive behavior of male gray tree frogs (Hyla versicolor) that have had experience in competitive interactions differs from that of males maintained in relative social isolation, and 2. That winner and loser effects occur in this species. We tested theses hypotheses by staging aggressive interactions between males and comparing the likelihood of winning, the escalation and the duration of interactions between males with and without different levels of aggressive experience. 

Results/Conclusions

Our preliminary data suggest that an individual’s past experience may influence the characteristics of its future aggressive interactions. Specifically, we found that individuals that were more socially isolated engaged in longer duration interactions that socialized males. The duration of a previous interaction was also negatively related to the duration of a subsequent interaction, but only for winners. We did not, however, find any evidence of winner and loser effects. We conclude that studies of social behavior in anurans should consider the history of interactions among individuals to explain broader patterns of signaling.