Determining vocal interactions and call timing in chorusing frogs: The contributions of Peter Narins

Abstract

Numerous species of frogs call synchronously in a chorus by timing their calls to avoid call-overlap with conspecific neighbors. Although synchronous calling is most likely maintained by a call oscillator, several species of frogs including the Puerto Rican treefrog Eleutherodactylus coqui can adjust the timing of the oscillator period over a wide range so as to maintain call synchrony with competing stimuli. Here we describe some of the playback experiments performed by Peter Narins and his co-worker Randy Zelick on the timing capabilities of the oscillator in the coqui frog, particularly the ability to rapidly alter timing even when the silent window had a random onset and was short in duration. Narins recognized that characterizing calling behaviour in isolation, with synthetic stimuli, did not fully describe the acoustic challenges faced by calling males in natural assemblies. Consequently, Narins and his co-worker Jeffrey Brush obtained individual call timings from groups of two to five vocally interacting coqui frogs in a natural assembly. They showed that some males actively avoided call overlap with two, maybe three neighboring conspecifics, while some actively jammed a neighbor. The impact of these seminal studies, and the technical challenges that were overcome by Narins are discussed.