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1 May 2014 Use of stable isotope analysis to identify food-conditioned grizzly bears on Alaska's North Slope
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Managers often must decide whether to use non-lethal intervention (e.g., hazing or relocation) or lethal removal for resolving bear–human conflicts. Bears with a history of anthropogenic food use are less likely to respond favorably to non-lethal intervention. Stable isotope analysis can be a useful tool to determine a bear's history of anthropogenic food use. We analyzed nitrogen (N) and carbon (C) stable isotopes in 51 hair samples collected between 1991 and 2006 from 30 grizzly bears (Ursus arctos), and their likely food items, from the oilfield region of Alaska's Arctic Coastal Plain (USA) to evaluate the feasibility of using stable isotopes to identify human food use in bears without direct observation. δ15N values varied by >4‰, indicating a trophically diverse diet. We found differences in isotopic values between bears that we had observed on a diet of natural foods (NF) only and those on a predominantly anthropogenic diet (food-conditioned [FC]). For 12 FC and 15 NF bears, mean δ15N values were 6.6‰ (0.26 SE) and 4.8‰ (0.12 SE) and mean δ13C values were −20.4‰ (0.3 SE) and −23.0‰ (0.14 SE), respectively. We confirmed that 3 putative NF bears whose home ranges overlapped the oilfields were likely NF bears. Isotope analysis confirmed visual observations of bear feeding behavior, and in the absence of extensive field observations could be used to determine whether an individual bear is likely to respond favorably to non-lethal management.

International Association for Bear Research and Management
Torsten W. Bentzen, Richard T. Shideler, and Todd M. O'Hara "Use of stable isotope analysis to identify food-conditioned grizzly bears on Alaska's North Slope," Ursus 25(1), 14-23, (1 May 2014).
Received: 18 January 2013; Accepted: 1 January 2014; Published: 1 May 2014

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