Relationships between repertoire size and organization of song bouts in the Grey-crowned Warbler (Seicercus tephrocephalus)

Abstract

The complexity of bird song could serve as an indicator of male quality. Repertoire size is a widely used measure of song complexity. However, little is known about the influence of repertoire size on the song sequencing patterns. At the same time, individual variability of song sequencing and its relation to repertoire size could be important for intraspecific communication. It is unlikely for an individual to count and compare full repertoires. Instead, they are more likely to rely on patterns of song performance. I analyzed the intraspecific variability in the song sequencing and its relation to the repertoire size in the Grey-crowned Warbler (Seicercus tephrocephalus). Advertising vocalization of males with larger repertoires turned out to be more determined and predictable than of the males with smaller repertoires. This pattern might reflect different learning abilities of males with different repertoire sizes. Learning abilities, in turn, might reflect male quality and/or age. However, these patterns could not be evaluated by analyzing short song sessions and it is very unlikely for other individuals to estimate them. However, these patterns influenced the other parameters of song organisation which could be estimated from short song sessions (such as versatility and song switching rate). Thus, for other individuals the latter may serve as an indicator of a male’s repertoire size.