Territory dynamics and patterns of female recruitment in Red-winged Blackbirds (Agelaius phoeniceus)

Publisher Website
Google Scholar
Abstract
The territorial boundaries defended by male Red-winged Blackbirds (Agelaius phoeniceus) shifted over the course of the breeding season. The establishment of new males in a colony, the redefinition of boundaries among neighbors, and the recruitment of new females were all related to changes in boundary locations. No significant correlations were found between harem size and either territory size or the abundance of preferred nesting sites. High rates of aggressive interactions did, however, coincide with the recruitment of new females and accompanied territory shifts. Many boundary changes were associated with the guarding by males of females that were showing interest in nest sites outside the area formerly defended by the male. If a female's behavior in an area precipitates conflicts among neighboring males, then it could be a mechanism whereby females simultaneously compare the attributes of males and influence the quality of their territories. Such a mechanism would ensure that a female obtains what she has determined to be the best available nest site and a male that can defend her choice. A more active role for females should be included in models of the evolution of mating systems.