Do the sexes tend to segregate in roe deer in agricultural environments? An analysis of group composition

We studied the composition of European roe deer, Capreolus capreolus (L., 1758), groupings in agricultural fields in northern France throughout an annual cycle to examine whether adult males and adult females tended to live in separate groups as is usually reported for gregarious ruminants. In April, shortly after the beginning of territoriality in mature males, single-sex groups were more frequent than expected by chance, evoking the grouping pattern reported in many territorial antelope species living in open landscapes. In contrast, mixed-sex groups were more frequent than expected by chance from October to January when adult males were no longer territorial and when large groups were formed. In addition, during this last period, females with attendant young were less sociable towards adult conspecifics than were males. Females with attendant young are known to be less sociable than adult males in several other deer species of the subfamily Odocoileinae. We hypothesize that this “sex-biased sociability” explains both the over-frequency of mixed-sex groups recorded in our roe deer population and the grouping patterns exhibited by sexually segregating Odocoileinae species.