Aggressive and territorial behaviour in female Red-winged Blackbirds

Abstract

Female Red-winged Blackbirds were observed to interact aggressively with conspecific females during the breeding season. Redwing females attempted to repel intruding females through the use of vocalizations, displays, and aggressive chases. Mapped positions of marked individuals indicated that female Red-winged Blackbirds recognized male territory boundaries and defended subsections of the male's territory against new intruding females and against harem mates. Female vocalizations advertising territory ownership were clumped in time early in the breeding season, suggesting that neighbouring individuals were interacting vocally. These results support the competitive version of the polygyny threshold model. The observed aggressive interactions, territorial behaviour, and vocal interactions suggest that female Red-winged Blackbirds attempt to deter further recruitment into harems.