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Description

Individual dietary variation in sexually dimorphic predator populations arises from phenotypic traits, preference, prey availability, and competition. We tested competing hypotheses for how diet similarity among cougars (Puma concolor) is influenced by sex, seasonal prey availability, and home range overlap in the southern interior of British Columbia, Canada. We proposed four hypotheses: (1) prey availability—overlapping individuals share similar diets due to access to the same prey base; (2) resource competition—overlapping individuals diverge in diet to minimize competition; (3) resource partitioning—diet similarity peaks at intermediate overlap; and (4) null—sex and season explain similarity irrespective of overlap. We analyzed diet data from 27 female and 11 male cougars (875 kill sites) and extrapolated prey availability from 146 remote cameras to test for sex-based differences in prey selection across winter, migration, and summer. We then used a pairwise approach to model diet similarity between individuals. Males generally killed larger prey (e.g., moose, elk), while females killed more deer, with differences in deer species selection in the Boundary study area where fewer large prey were available. We found support for resource partitioning between female–female dyads and for resource competition between male–female dyads. Diet similarity was lowest in summer when home ranges were largest and highest in winter when ranges were smallest. Our findings highlight the complexity of predation patterns and the roles of sexual dimorphism, seasonal prey availability, and resource partitioning in shaping prey use among spatially overlapping territorial predators in multi-prey systems.