Meeting Abstract

45.3  Jan. 6  Signal timing by the gray treefrog, Hyla chrysoscelis: responses to conspecific and heterospecific advertisement calls MARSHALL, Vincent T.*; GERHARDT, H. Carl; University of Illinois; University of Missouri marshallvt@life.uiuc.edu

Breeding aggregations of acoustically signaling animals often comprise multiple species sharing a common communication channel. Whether and how an individual adjusts the timing of its signals relative to those of other signalers, an often important predictor of the responses of receivers, may therefore depend on the species identity of its neighbors. In this study, I examined how males of the gray treefrog, Hyla chrysoscelis, adjusted the timing of their advertisement calls relative to the calls of conspecifics and those of the closely related, syntopically breeding species, H. versicolor. During interactions between calling males, calls were timed such that there was little signal overlap regardless of whether the neighbor was conspecific or heterospecific. In response to playbacks of conspecific and heterospecific advertisement calls, males generally avoided producing calls during either stimulus type, and instead initiated them during the silent gaps between stimuli. There were, however, differences in the response to conspecific and heterospecific signals. Males produced calls with relatively short latencies after the heterospecific calls, which resulted in their often rapid placement within the silent intervals between stimuli. In contrast, calls produced after conspecific stimuli had significantly longer latencies, resulting in a distinct gap between the end of the stimulus and the male�s call. This plasticity in signal-timing behavior is discussed in light of hypotheses for the function of adjustments in the timing of acoustic sexual signals.