© 1991 International Society for Behavioral Ecology
research-article |
Basal song rate variation in male red-winged blackbirds: sound and fury signifying nothing?
Department of Biology, Carleton University Ottawa, Ontario K1S 5B6, Canada
ABSTRACT
Male red-winged blackbirds (Agelaius phoeniceus) vary substantially in how much they sing. We tested whether song rate reflected the male’s quality, the quality of his territory, or his frequency of interaction with potential competitors. Song rate declined with the seasonal decline in nest initiations, suggesting that song is used to attract females. However, males with higher song rates did not obtain larger harems. This suggests that females do not use male song rate to assess either male quality or territory quality. If song rate signals male quality to male rivals, and if territory owners are of higher quality than floaters, then owners' song rates should be higher than those of floaters. However, when we removed territory owners temporarily, the song rate of their floater replacements was similar to that of the original owners. Finally, a male’s song rate was not affected by how frequently he chased intruders, or by the proximity or number of neighbors he had. In short, the only information that basal song rate of redwinged blackbirds appears to provide to conspecifics is that the territory is occupied. In simulated territory takeover attempts, however, song rate was significantly higher than the basal rate. Thus, more may be revealed by the singer in these situations. [Behav Ecol 1991;2:123-132]