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Like many sexually dimorphic ungulates, bighorn sheep,Ovis canadensis, form sexually segregated groups. Nursery groups include females, lambs and subadult males, while adult males form bachelor groups. Previous hypotheses to account for sexual segregation in ungulates have suggested sexual differences in energy requirements, predation risk and social preferences. I tested the hypothesis that differing nutritional demands, due to sexual dimorphism in body size, would lead to different movement patterns and time budgets. If ruminating/foraging schedules differed according to body size, males and females could not synchronize their activities and therefore would segregate by sex. To test this hypothesis, I observed a population of marked bighorns. I recorded the time males and females spent lying, grazing or walking during 8–14h of focal-animal observations. Initial and final location of groups and steps …