Intra- and Interspecific Vocal Behavior of the Neotropical Treefrog Hyla microcephala

Abstract

The vocal communication of Hyla microcephala was studied in central Panama. We recorded natural interactions between males and conducted playback experiments using conspecific and heterospecific calls. Males employ both advertisement and aggressive calls which consist of a buzz-like introductory note often followed by secondary click notes. Advertisement calls show little variation in temporal features, whereas aggressive calls are quite variable. Playback of both conspecific advertisement calls and aggressive calls at high intensity elicited a significant increase in aggressive calling. Males increased the duration of aggressive call introductory notes in response to increasing playback intensity. Aggressive calls with long introductory notes were also used during close vocal or physical encounters with both conspecific males and H. ebraccata. In most cases, playback of heterospecific calls were ineffective in eliciting increased aggressive calling. Males synchronized and often added click notes to advertisement calls in response to conspecific and heterospecific calls. Call playbacks also elicited an increase in calling rate. When interrupted, males often abruptly terminated calls or added secondary notes to them. Males typically alternate individual notes in overlapping calls. Internote intervals in overlapping multi-note calls are longer than those in non-overlapping calls, reducing the probability of note overlap.