Songs of the Alder Flycatcher (Empidonax alnorum) and Willow Flycatcher (Empidonax traillii) are Innate

Abstract

Abstract I studied the song development of five Willow Flycatchers (Empidonax traillii) and four Alder Flycatchers (Empidonax alnorum) taken from nests at 7-10 days of age. Three Willow Flycatchers and four Alder Flycatchers were tutored with songs of the other species, and two Willow Flycatchers served as controls, hearing only conspecific songs. All nine subjects, both females (when administered exogenous testosterone) and males, and both experimentals and controls, produced remarkably normal songs; slight differences between songs of wild and experimental subjects could be attributed to motivational states rather than to the effects of acoustic isolation in the laboratory. I found no microgeographic variation of wild songs, no evidence of learning from a tutor tape, nor any similarity of song characters among kin. The vocal development of these suboscine flycatchers is strikingly different from that of typical oscines, where vocal learning is the rule.