Resources, not male mating strategies, are a determinant of social structure in Gunnison's prairie dogs (Cynomys gunnisoni)

Abstract

AbstractPrevious studies of Gunnison's prairie dogs, Cynomys gunnisoni, have reached different conclusions about the factors influencing sociality in this species. In this study I tested whether Gunnison's prairie dog social structure was resource-based or whether male mating strategies drive the organizational patterns observed. Group size, where the term group refers to individuals occupying the same territory, was predicted by territory size and density of food available. The spatial overlap of adults within territories was positively correlated with spatial patchiness of food resources. All group members participated in territory defense, although adult males engaged in significantly more intergroup aggressive interactions. There was no significant difference in adult male and female home range size. The number of female home ranges that any given male home range overlapped was not correlated with male body mass, male home range size, or territory size. Contrary to predictions of typical mammalian male mating strategies, adult females ranged significantly further than males during the mating period. Body mass of males and nonreproductive females was similar, whereas that of reproductive females was smaller. In addition, males and females did not differ in size, based on skull length and skull width. Results from this study strongly suggest that patterns of space use and social structure in Gunnison's prairie dogs are the result of individual responses to resource abundance and distribution and are not due to male mating strategies, such as resource defense or female defense polygyny.