Social organization in a North African ground squirrel.

Abstract

Research on sociality in temperate ground-dwelling squirrels has focused on female philopatry and other life history trade-offs, which are influenced by constraints in the duration of the active growing season. Temperate ground-dwelling squirrels that experience high predation pressure, are large in body size, and have a short active season show a more complex social organization. Little information is available on the African ground squirrels, which are active year-round suggesting that instead of a short active season other selective pressures influence their social organization. We examined the social organization of Barbary ground squirrels, Atlantoxerus getulus, and compared the social organization of temperate and African ground dwelling sciurids. Anecdotal accounts on Barbary ground squirrels’ social organization suggest that they are solitary or gregarious, or that they live in small family groups. We recorded the group size, composition, cohesion and genetic relatedness of the invasive population on the arid island of Fuerteventura, Spain. Our data indicated that females live in small [1-8] all-female kin groups separate from adult males and unrelated adult males share sleeping burrows with immature individuals of either sex. We observed sex-biased dispersal with males as primarily the dispersing sex and females mainly philopatric. Females sleep solitarily during gestation and lactation and either communally or singly nest after juvenile emergence. During the day, males and females can be active in the same area. Barbary ground squirrels are social because the squirrels share sleeping burrows and show spatiotemporal overlap. Barbary ground squirrel’ social organization resembles that of the closely related Cape ground squirrel instead of the temperate ground-dwelling sciurids, although they are more temperate, seasonal breeders. In addition to acquiring knowledge about the social organization of an unstudied species, this paper contributes to the understanding of ecological drivers explaining sociality, and the evolution of different social organizations in ground-dwelling sciurids.