| Abstract: | ![]()
Northern mockingbirds (Mimus polyglottos) sing more during nest building than at any other time in the breeding cycle. Playback tests in which the songs of nest-building and unmated males were played to mated males during incubation and nest building were conducted to determine if nest-building song is a mate guarding signal. Analyses indicated no greater aggressive response to song during nest building versus incubation in mated males. Singing itself was never evoked by song playback, and neither mated nor unmated males responded differently to songs produced by unmated versus nest-building males. The aggressive responses of unmated males were greater than those of mated males nest building without offspring, and males nest building with older offspring present responded as much as unmated males and more than males nest building without offspring. Aggressive response to song playback in once-mated males, whose mates disappeared during the breeding season, did not change as much as two months after disappearance of the mate. Nonetheless, ambient song production increased significantly above that apparent in the same birds when mated. These experiments indicate that aggressive reaction to song playback fluctuates across breeding contexts but not as predicted by the use of song as a mate guarding signal and not in a manner that parallels natural fluctuations in song production. (PsycINFO Database Record (c) 2010 APA, all rights reserved) |
