The alpine accentorPrunella collarisis a territorial and polygynandrous mating species. The breeding unit is a group consisting of about seven members who share a group territory which contains all the resources necessary for living. Each female holds a small territory around her own nest within the larger group territory. Supplemental food in the form of millet seed was provided for a total of 23 group territories to test the hypothesis that the abundance and distribution of food influences the size of a female's territory and her dispersion pattern which, in turn, determine the mating system. Both males and females had regular access to the feeders, but females and groups provided with feeders did not have smaller territories than those without feeders. No groups were divided into two by offering extra food. Provision of extra food resulted in an increase of group size but did not alter the sex ratio. All members, including new settlers, were sexually active and the sexual relationships among the members of a group were still multiple matings. Food addition did not prompt the fed females to choose nest sites nearer the feeder. Nest sites were restricted to particular rocky slopes and non-vegetated areas which were invariably free from snow each year due to the effects of strong winds and the topography. Females showed a nest-site fidelity for successive years. The reason why supplemental food had no effect on the territory size or dispersion of female alpine accentors is discussed.
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