Song response to male intruders and prospecting females in the pied flycatcher, Ficedula hypoleuca

Abstract

Singing in the pied flycatcher, Ficedula hypoleuca, was examined in both intra- and intersexual contexts. Song responses to male intruders and prospecting females were investigated by introducing caged conspecific birds into the subjects’ territory and recording song immediately prior and after treatment. Syllable repertoire, two measures of strophe diversity, strophe length and syllable switching were analysed using sonograms of the song. Pied flycatchers reduced their repertoire size and tended to increase their syllable switching and shorten their strophe length in response to intruding males. They did not significantly alter their song after encountering a female. Older males switched syllables at a higher rate after a female encounter than did juvenile males. Plumage traits were not correlated with song responses to males or to females. Pied flycatchers did not respond differentially to male intruders and prospecting females when responses to the two sexes were compared. The effect of nestbox provision and the migratory behaviour of these birds is discussed in relation to these findings. It is concluded that no strong indication of the dual function hypothesis hypothesis of birdsong was found in this study, though this may be a function of the sample size and further investigation may be warranted.