Influence of the Natal Environment on Dispersal of White-Footed Mice

We explored the relationship between several aspects of the natal environment and dispersal distances of white-footed mice, Peromyscus leucopus, in a 2-ha oak/hickory woodlot northeast of Bowling Green, Ohio, from 1991 to 1993. Litters of mice in nestboxes were marked at an early age. We evaluated litter size, the number of males and females in the litter, litter sex ratio, weanling survival to adulthood, and mother's parity as proximate factors that might affect dispersal. Dispersal was quantified as the straight-line distance between the mother's center of activity and that of her adult offspring. Of 401 mice from 82 litters, 78 (19.5%) were recaptured as adults. Males dispersed significantly farther than females. Females from small litters dispersed shorter distances than females from median or large litters. Females also dispersed farther with increasing numbers of male siblings. However, the proportion of males in the litter was not related to dispersal distance of either sex. Males with two or more sisters dispersed farther than did males with fewer than two sisters. Males from their mother's first litter dispersed farther than males from subsequent litters; however, the presence or absence of the mother at the time of dispersal was not related to male dispersal distance. Our results suggest that inbreeding avoidance between siblings may lead to male-biased dispersal, and that interactions between siblings may be more important than interactions with the mother in determining dispersal distances.