Population structure and dispersal of Peromyscus leucopus on Muskeget Island

Abstract

A 6-year experimental study was used to examine the effects of resident, breeding males on recruitment and dispersal of juveniles on Muskeget Island, Massachusetts. Dispersal was studied by providing a vacant area into which mice could move. Residency and recruitment in males depended on weight but not breeding condition. Dispersing males were a random sample of the adjacent control population. Dispersing females weighed less than all other mice and were more likely than control females to have perforate vaginae and small lactation tissues. Although the patterns of density variation and breeding activity were similar to those of other P. leucopus populations in New England, our results are unlike those of most other studies of population regulation in Peromyscus spp. and suggest that males were not territorial and did not limit the recruitment of juveniles. A hypothesis is proposed to explain the anomalous effects of males on density limitation and is based on density-dependent strategies employed by males to acquire access to breeding females.