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Improving Black Bear Management Through Stable Isotope Assessment of Bear Food Habits in the Northeast

Principal Investigator/Project Leader: 
Department of Project: 
Environmental Conservation Dept.
Project Description: 

Managing conflict between people and black bears is a significant challenge confronting wildlife professionals. In addition, the frequency of conflict is expected to rise as black bear and human populations grow. The challenge is heightened by the species’ large geographic range, acceptance of human disturbance, and propensity to exploit anthropogenic food sources such as garbage cans, bird feeders, apiaries, fruit orchards, and agricultural fields. Understanding and quantifying the range of variation in the nutritional ecology of free-ranging black bears in the Northeast is important for effective management of the species because foraging opportunities strongly influence black bear habitat selection, home range size, productivity, movement rates, population growth, distribution, and potential for conflict with humans.

The most effective and efficient management strategy for dealing with problematic black bears is contingent upon correctly identifying which bears are most likely to cause conflict; plasticity in regional bear behavior and foraging strategies will likely necessitate localized adaptive management strategies. For instance, it has been demonstrated that social learning and rearing condition is a strong predictor of whether a bear will utilize anthropogenic food. This has important implications for mitigation options, as female bears would serve as a reservoir for the transmission of conflict behavior. In contrast, it has also been demonstrated that black bears can be distributed in such a way that dominant bears monopolize access to anthropogenic food sources. Management strategies would differ if a certain demographic group disproportionately concentrates on anthropogenic food resources, or if a small number of specialist bears concentrate on human food as opposed to an equivalent level of foraging among all bears within close proximity of anthropogenic food sources. We plan to use isotopic analysis (the composition of  carbon (13C/12C) and nitrogen (15N/14N) stable isotope ratios in animal tissue) to identify the variation in black bear diet across the urban-rural gradient in the Northeast, to examine how variability in foraging patterns influences bear ecology and human-black bear conflict, and to estimate the proportion of bears that consume human food.