Evaluating the extent and drivers of dietary specialization in polar bears (Ursus maritimus) across Western Hudson Bay

Climate warming has caused significant reductions in the extent of annual sea ice. As an ice-dependent species, the polar bear (Ursus maritimus) relies on the ice to hunt, making it susceptible to large-scale changes in sea ice and prey availability. My thesis sought to investigate individual-level foraging habits of polar bears in Western Hudson Bay from 2004-2021. I used fatty acid analyses and the proportional similarity index to investigate the extent and drivers of individual dietary specialization and interindividual differences in foraging habits. My results indicated a significant proportion of specialization, with the degree of specialization differing across age and sex classes. Annual snow depth and the North Atlantic Oscillation (NAO) were strong predictors of specialization, resulting in increased specialization with increasing snow depth and NAO. Continued monitoring efforts are necessary to ensure interindividual variation in foraging is considered when modelling the responses of polar bears to future climatic warming.