Intrasexual territoriality in woodchucks (Marmota monax) [Territorialité intrasexuelle chez les marmottes communes d’Amérique].

Résumé

Spatial organization in woodchucks (Marmota monax) reportedly ranges from nonterritorial to territorial, and researchers often invoke population density to explain population differences. I observed a population of individually marked woodchucks in southern Maine to document their spacing system. I measured home range size, % overlap, and response to intruders. However, I infrequently observed encounters between individuals. Males had larger core home ranges than females, but males and females did not differ from each other in amount of intrasexual overlap. Females tended to overlap males' ranges more than males overlapped females' ranges. Within each sex, intersexual overlap in home ranges exceeded intrasexual overlap. Analysis of data from other populations revealed that home range sizes decreased with increasing population density and that intersexual overlap always surpassed intrasexual overlap. As density increased, woodchucks increased the amount of intrasexual overlap, but intersexual overlap did not change. Thus, woodchucks appear to display intrasexual territoriality. As density increases, however, they share more of their home ranges with members of the same sex, perhaps developing more tolerance.