Social organisation of female field voles Microtus agrestis in a population in Southern England

摘要

The social organisation of a population of Microtus agrestis (Linnaeus, 1761) was studied by live trapping and radiotracking in southern England. Radiotracking revealed significant differences in both female home ranges and core areas with breeding condition. Lactating females had the smallest home ranges and core areas, and pregnant females the largest. There were no significant differences in female home range and core areas during the breeding season or between years despite different densities. Females were only territorial whilst lactating during which time their core areas were small. There were some overlaps of core areas among females at the beginning of the breeding season which are thought to be due to familiarity or kin associations. Associations between females were short-lived, lasting approximately one breeding event. As the breeding season progressed core areas became distinct suggesting a change to a territorial system although densities were low and most females were lactating. Patterns of social organisation among females were similar in both 1995 and 1996. Mean nearest neighbour distances tended to increase as the breeding season progressed and were uncorrelated with density.