Consumption of anthropogenic foods influences the nutritional and reproductive condition of hunter‐harvested black bears

The consumption of human food subsidies influences ecological processes, and can affect individual behavior and fitness with population level changes in abundance and distribution . American black bears Ursus americanus often consume human food subsidies, which have been correlated with increased bear body size, age‐specific fertility and mortality rates. We studied how consuming human food subsidies influences nutrition and reproduction for hunter‐harvested black bears in Wisconsin, USA. To estimate lifetime diets, we performed a bulk stable isotope analysis of δ 13 C and δ 15 N on 200 hunter‐submitted black bear tooth samples and corresponding dietary items (n = 335). We analyzed layers of cementum annuli, a calcified connective tissue deposited in mammalian teeth that can track seasonal changes in nutritional condition and reproduction for certain species, within tooth samples (n = 164). We calculated lifetime nutritional condition for individuals and nutritional condition during litter years for reproductive sows that controlled for differences between ages and sex. We modeled the effect of diet on lifetime nutritional condition, reproductive nutritional condition, and variation in lifetime nutritional condition. Human food subsidies made up nearly half of the diet of the bears (males: median = 48%, 95% CI [34%, 73%]; females: median = 43%, 95% CI [33%, 62%]) with individual consumption varying from 13–86%. Cementum annuli widths were statistically indistinct between males and females until age four, when female widths narrowed, coinciding with sexual maturity and the nutritional cost of reproduction. Increased consumption of human food subsidies was positively correlated with lifetime nutritional condition and variation within nutritional condition and negatively correlated with reproductive nutritional condition, but the magnitude of the effects were small. As the interface between urbanization and wildlife increases, discerning how individual variation in diet influences components of fitness (i.e. body condition and reproductive output) is important for managing harvested populations, including American black bears.