SPACING AS A PREDICTOR OF SOCIAL ORGANIZATION IN KANGAROO RATS (DIPODOMYS HEERMANNI ARENAE)

Abstract

Listen

Translate article

We examined intraspecific space use of free-ranging kangaroo rats (Dipodomys heermanni) during the breeding season using behavioral observations and radiotelemetry. Home ranges of males were significantly larger than those of females. Female D. heermanni maintained exclusive territories with essentially nonoverlapping home ranges, whereas home ranges of males overlapped with both same- and opposite-sex conspecifics, reflecting the different strategies of the different sexes. This follows a general pattern found in mammals in which spacing reflects limiting resources. There was, however, high individual variation in home range size for males, which may suggest a role for social interactions in determining spatial behavior in this species. D. heermanni, a medium-size species, appears intermediate in space use compared with the larger D. spectabilis and the smaller D. merriami. Spacing systems characterize the pattern of distribution of individuals in a population in space and time. The location of an individual is influenced by presence or absence of other individuals (Brown and Orians 1970), distribution of food resources (Covich 1976; Emlen and Oring 1977), and extent of suitable habitat. The social processes by which resources are allocated among members of the population determine spatial organization. Hence, spatial organization of a population can be used to predict its social organization. Patterns of space use by mammals have been the subject of numerous discussions and empirical tests (Lott 1991). One metric for space use is home range size, which is a compromise between environmental conditions and selective factors such as primary production, individual metabolic requirements, predation, and social pressures. These interacting factors often lead to different levels of social interaction between and within species. For solitary rodents in particular, variation in use of space is related to sex, season, geography, and competitive behavior (Armitage 1999; Ebensperger and Bozinovic 2000;