Population Biology of Microtus arvalis. II. Natal and Breeding Dispersal of Females

SUMMARY (1) Using radiotelemetry on individuals marked within 2 days of birth, we documented natal and breeding dispersal in solitary and grouped breeding females of the common vole, Microtus arvalis (Pallas 1779). We tested the hypothesis that breeding dispersal results from nest sites being too low in quality. (2) Breeding dispersal occurred only in solitary breeding females within 24 h prepartum when both grouped and solitary breeding females built a new nest either within the same burrow (residents) or 16-537 m from their burrow (dispersers). Solitary females provided with large artificial nest sites dispersed significantly less frequently than females provided with small artificial nest sites or living at small natural burrows. (3) Natal dispersal occurred on the first day that a vagina could be identified and in eleven females was concomitant with matings leading to a first litter. Littermates settled in the same areas.