Deciding whether to monitor, aversively condition, relocate, or destroy a problem black bear (Ursus americanus) can be difficult for wildlife managers. Understanding the extent of anthropogenic foraging within bear populations can provide insight for management decisions about black bears. An innovative way to estimate opportunistically the amount of anthropogenic food in an individual or a population of bears is through stable isotope analysis (SIA), where hair samples can provide an index of assimilated nutrients (i.e., diet) for the period of hair growth. Our objective was to use SIA to determine whether there was a difference between diets of bears using urban areas and bears using adjacent wildland areas for forage. We collected hair samples from 16 bears captured between April and September 2009 (i.e., urban bears) within the urban area of Missoula, Montana, and from 15 bears harvested during a spring bear hunt (April 15 to May 15, 2009) in hunting units adjacent to Missoula (i.e., wildland bears). We compared isotope values of urban and wildland bears in a δ13C and δ15N isotope mixing space that contained 3 potential dietary components (generalized plant baseline, meat, and cornbased foods [i.e., garbage]) using a Bayesian modeling framework. The contributions of the 3 potential dietary components were not different between urban and wildland bears, suggesting that human-generated garbage was not a significant diet source during the 2008 hair-growth period for bears. In other areas or years, however, where a larger portion of the bear population consumes garbage, SIA will be able to opportunistically estimate the amount of garbage in diet.
Merkle, Jerod A.; Derbridge, Jonathan J.; and Krausman, Paul R.
"Using Stable Isotope Analysis to Quantify Anthropogenic Foraging in Black Bears,"
Human–Wildlife Interactions: Vol. 5
, Article 16.
Available at: http://digitalcommons.usu.edu/hwi/vol5/iss1/16