Species-specific recognition in birds: an experimental investigation of Wilson's storm-petrel (Procellariiformes, Hydrobatidae) by means of digitalized signals

Abstract

Most acoustic studies on birds dealing with species specificity have concerned the territorial function of the song in passerines. We studied species specificity in a non-passerine bird, Wilson's storm-petrel (Oceanites oceanicus). Males of this species attract females by uttering a chattering call, which acts as a premating isolating mechanism. We analysed the encoding of species specificity in the call by measuring the variation in its physical features. We then experimented in the field with played-back computer-synthesized signals and identified the relevant cues that elicited species recognition, namely the modal frequency and the durations of both syllable and silence. We relate our results to species specificity in passerines, and emphasize differences in the responses with respect to sex and status of responding birds, the differences being due to the meaning of the species-specific signal for the receiver.