Infanticide as a male reproductive strategy has a nutritive risk effect in brown bears

Behavioral strategies to reduce predation can incur costs (i.e. risk effects). A common strategy to avoid predation is spatiotemporal avoidance of predators, in which prey typically trade optimal resources for safety. Analogous with predator-prey theory, risk effects should also arise in species with sexually selected infanticide (SSI), in which females with dependent offspring avoid infanticidal males. In brown bears (Ursus arctos), SSI is common and explains spatiotemporal segregation among reproductive classes. Here, we show that females with cubs-of-the-year had lower quality diets than conspecifics during the SSI high-risk period, the mating season. After the mating season, their diets were of similar quality to diets of their conspecifics. Our results suggest a nutritive risk effect of SSI, in which females with cubs-of-the-year alter their resource selection and trade optimal resources for offspring safety. We suggest that risk effects can be widespread among species with SSI, an...降低捕食风险的行为策略往往会带来相应代价（即风险效应）。规避捕食的常见策略为时空上回避捕食者，此时猎物通常会以最优资源为代价换取安全。与捕食者-猎物理论的逻辑一致，存在性选择杀婴（sexually selected infanticide，SSI）的类群中也应出现此类风险效应：带有依赖后代的雌性会回避实施杀婴行为的雄性。棕熊（Ursus arctos）中普遍存在性选择杀婴现象，该现象可解释不同繁殖类群间的时空分离格局。本研究显示，在性选择杀婴的高风险时期——交配季，带有当年幼崽的雌性个体的日粮质量低于同种个体；而在交配季结束后，其日粮质量与同种个体无显著差异。研究结果表明，性选择杀婴存在营养风险效应：带有当年幼崽的雌性会调整其资源选择行为，为保障后代安全而以最优资源为代价。本研究推测，风险效应可能广泛存在于存在性选择杀婴现象的物种种群中，……