TERRITORY ACQUISITION AND SOCIAL FACILITATION BY LITTER-MATE TOWNSENDS VOLES (MICROTUS-TOWNSENDII)

The present study investigates the influence of the presence of same-s ex litter-mates on the attainment of breeding status by subadult Towns end's voles in natural populations. Males and females were less likely to disappear from their natal area (disperse) and more likely to dela y sexual maturation if they had at least one live same-sex litter-mate within the natal home-range when reaching adolescence. Furthermore, a mong male and female sexually mature subadult voles, the probability o f persisting near the natal area and hence recruiting as a breeding re sident was higher for those individuals that had a same-sex litter mat e in their vicinity when maturing sexually. A removal experiment sugge sted that the increased probability of recruitment of members of famil y groups was not caused by intrinsic differences between offspring fro m different litters but results from social interactions between same- sex litter-mates. Dispersal tendency by subadult voles is therefore a highly flexible trait which is influenced by the social environment ex perienced by individuals.