Song variation in a population of Alder Flycatchers

Abstract

Song variation has been studied extensively over the past 50 yr but almost entirely in oscine passerines. Although learning is an essential component of song development in most, if not all, oscines, there is no definitive evidence for song learning in suboscine passerines. This suggests that the patterns and extent of individual and geographic variation may differ between these groups as well. We examined individual variation in the “fee-bee-o” song in a population of Alder Flycatchers (Empidonax alnorum) in southwestern Alberta. Songs of individual males were recorded during the breeding season in 2001. We measured temporal and frequency variables of songs and conducted univariate and multivariate statistical analyses to characterize variation within and among individuals. There was little variation among the songs of an individual male during single recording sessions and across recordings made over the breeding season. All measured variables varied significantly more among than within individuals. Discriminant function analysis assigned 91–100% of songs to the correct individual. Therefore, there was sufficient variation among individual males to identify them statistically and, potentially, to permit individual discrimination by the birds.