Nutritional ecology and wildlife conservation: the role of macronutrients in human-bear conflict (#482)
The human nutritional environment has changed substantially since the times of hunter-gathers. Notable in this regard is the relatively large increase in the proportion of the macronutrients carbohydrate and lipids in the human diet relative to protein. This human preference for diets high in non-protein energy is likely due to the ancestral environment in which high-carbohydrate and high-lipid foods were frequently limiting. Other omnivorous animals also show similar macronutrient preferences to humans, including non-human primates and the grizzly (brown) bear (Ursus arctos); however, little is known regarding how the current anthropogenic nutritional environment influences the foraging behavior of wildlife and associated human-wildlife conflict. In this talk, we discuss how behavioral regulatory mechanisms aimed at optimizing macronutrient intake may influence human-bear conflict, with a focus on the North American grizzly bear. We use nutritional geometry to demonstrate that nutritional mismatch between the availability of key natural foods high in non-protein energy (e.g. fruit and hard-mast) and the macronutrient preferences of grizzly bears (17% protein to 83% non-protein energy) likely drives human-bear conflict; in the absence of these key natural food resources (e.g. berry crop failure) bears are more likely to seek out high-carbohydrate and high-lipid foods from anthropogenic sources. Anthropogenic foods high in non-protein energy, such as agricultural products, garbage, and domestic livestock, may allow bears to optimize their macronutrient intake and mass gain in the absence of appropriate wild foods. This multidimensional nutrient-specific foraging model offers different predictions for bear foraging behavior than traditional approaches focusing on food, energy, or protein, and leads to further insight into why particular foods are so attractive to bears and more likely to be sources of conflict. More broadly, this nutrient-specific approach can provide insight into the nature of food-related wildlife behavior at the often turbulent interface of anthropogenic environments.