The social organization and territoriality of short-tailed shrew ( Blarina brevicauda) populations in old-field habitats

Abstract

The social organization of short-tailed shrew ( Blarina brevicauda) populations was studied using field and laboratory experiments and observation of a shrew population inside a large enclosure. Short-tailed shrew populations contain resident and nomadic components. Residents occupy small stationary areas at high prey densities and larger areas that are shifted frequently at low prey densities. Areas occupied by residents overlap minimally in winter, non-breeding populations. In summer breeding populations areas occupied by residents of the same sex do not overlap while those of residents of opposite sexes may overlap. Residents defend the area occupied against conspecifics. Scent markings along boundaries appear to maintain the spatial distribution of residents and deter intrusions by nomadic shrews. During encounters vocalizations function as offensive threats, and attacks and chases follow if the intruding shrew does not retreat. Visual communication appears to be less important than chemical and vocal communication in the defence of the area occupied. These data suggest that Blarina is a solitary territorial species.