Geographical assignment of polar bears using multi-element isoscapes.

Area of Science:

• Ecology
• Conservation Biology
• Wildlife Management

Background:

• Apex predators like polar bears (Ursus maritimus) face significant conservation challenges due to climate change and hunting.
• Effective management requires accurate identification of distinct subpopulations.

Purpose of the Study:

• To evaluate the effectiveness of stable isotope analysis in assigning polar bears to management subpopulations and ecologically defined groups.
• To explore the utility of isotopic profiles as a forensic tool for wildlife management.

Main Methods:

• Stable isotope analysis (¹³C, ¹⁵N, ²H, ¹⁸O) was performed on hair from over 1000 Canadian Arctic polar bears.
• Quadratic discriminant analysis and partitioning around medoids were used to define and assign individuals to isotopic clusters and isoscapes.

Main Results:

• A four-isotope model achieved ~80% assignment accuracy to pre-existing management subpopulations (range ~30-99%).
• Isotopic clustering provided high assignment accuracies, with four isotope groups yielding 74% accuracy.
• The study identified robust spatial isotopic structures within polar bear populations.

Conclusions:

• Stable isotopic profiles are a powerful forensic tool for polar bear conservation and management in Canada.
• The approach demonstrates potential for application to other threatened apex mammalian predators.
• Further research is needed to understand the drivers of observed isotopic patterns.