Territory and group living in the polygynandrous Alpine Accentor Prunella collaris

Abstract

The spacing system of Alpine Accentors Prunella collaris was studied on the summit of Mt. Norikura in central Japan for five breeding seasons. This species lived in groups (mean 7.2 individuals), sharing large areas of their individual home ranges within which all activities occurred. Membership of a group was closed and stable within a breeding season. The group home ranges overlapped little with each other, and antagonistic behaviour, including communal defence, was observed at the boundaries. Each female established an exclusive area around her own nest which she defended against other females (but not males) within the shared home range, but her activities (feeding, singing and mating) were observed over the whole of the group home range. Members of the same group moved around and fed together within the home range during the prebreeding season, but individual birds tended to become more solitary as the breeding season progressed. These results suggest that the primary breeding unit of Alpine Accentors is a group consisting of five to ten members who share a group territory which contains all the resources necessary for living and breeding, but this species is not a typical social one in which all members move around together within their group territory.