Ecology of polar bears in a changing climate

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The sea ice habitat upon which polar bears depend is vulnerable to projected climate change. Reduction in sea ice extent, duration, thickness, and snow cover, as well as displacement of the marginal ice zone can significantly impact reproductive success, foraging, migration patterns, and survivorship not only of polar bears, but also of their marine mammal prey. The objective of this research is to identify the underlying ecological processes that affect vital population rates (births, deaths, immigration and emigration) that determine changes in polar bear abundance. It involves the investigation of life history components of polar bears and the development of quantitative descriptions of the linkages between their life history and climate, sea ice, and prey. Research activities are focussed in 3 populations (Beaufort Sea, Foxe Basin, and Western Hudson Bay). Landscape ecology principles of habitat connectivity, fragmentation, movement corridors, and habitat patch size are the proposed framework for understanding climate change related impacts. Focus is placed on adult females to assess their reproductive success relative to space-use patterns. The long-term goal is the development of descriptive metrics and predictive capacity for understanding the impacts of climate variability and change on polar bears and their prey in a spatial-temporal context. The project involves significant innovation in 4 core areas: 1) Assessing the effects of climate and sea ice conditions on spatial and temporal patterns of polar bears movements via satellite tracking in conjunction with satellite ice imagery, 2) The effects of interannual variability and directional change in sea ice conditions on the phenotypic metrics, life history traits, and population dynamics, 3) Examination of cementum deposition in teeth collected from polar bears with inferences on life history events derived from annuli widths, 4) Use of physiological parameters such as serum urea/serum creatinine, leptin, and haptoglobin levels to assess fasting/feeding dynamics and health. The project will yield quantitative data on the relationship between polar bears and their environment that can be used to predict future ecological responses to climate change.