Explores polar bears in the Hudson Bay discussing their behaviors and threats to their survival such as pollution hunting land development and climate change. Includes resources and glossary

The ecological response of climate change is expected to be especially pronounced across the circumpolar Arctic. Predicted declines in sea ice extent and seasonal duration are expected to affect the foraging ecology of marine species, particularly polar bears (Ursus maritimus) that rely on stable sea ice patterns for various aspects of their life history. The goal of this thesis was to quantify body condition and characterize diet composition of polar bears in western Hudson Bay over a broad temporal scale (2004-2014), and identify potential environmental factors that may influence dietary shifts in one of the southernmost subpopulations of this species. Body condition was higher in adult and subadult females than males, consistent with energetic demands of gestation and lactation. Body condition also declined over time in adult and subadult males and females and was influenced by sea ice breakup and freeze-up dates. These trends suggest that the historical climate-driven declines in polar bear body condition documented in western Hudson Bay have continued. Variation in diet composition and dietary niche breadth across age, sex and reproductive groups suggest foraging behaviour is structured by energetic demands, intraspecific competition and sexual body-size dimorphism. Specifically, variation in diet and niche breadth across females was influenced by age (experience), energetic state and avoidance behaviours. Variation in diet composition and niche breadth between male and female bears, however, was more likely structured by body size, whereby capture of larger prey types and a broader range of prey species occurred with increasing body size. Body condition was positively related to niche breadth in adult males but negatively related to niche breadth in females with dependents, suggesting that less-selective foraging (scavenging) does not benefit body condition among reproductive females. Inter-annual fluctuations in diet composition reflected shifts in local prey availability during the study period, and sea ice breakup date influenced the diets of subadults and family groups, suggesting an increased sensitivity to sea ice conditions. Therefore, inter-annual variability in diet and declines in polar bear body condition likely reflect contemporaneous changes in sea ice availability and population demography, and have implications for the long-term conservation of this subpopulation.

In Arctic Canada, Hudson Bay is a site of great exploration history, aboriginal culture, and a vast marine wilderness supporting large populations of marine mammals and birds. These include some of the most iconic Arctic animals like beluga, narwhal, bowhead whales, and polar bears. Due to the challenges of conducting field research in this region, some of the mysteries of where these animals move, and how they are able to survive in such seemingly inhospitable, ice-choked habitats are just now being unlocked. For example, are polar bears being replaced by killer whales? This new information could not be more salient, as the Hudson Bay Region is undergoing rapid environmental change due to global warming, as well as increased pressures from industrial development interests. A Little Less Arctic brings together some of the world’s leading Arctic scientists to present the current state of knowledge on the physical and biological characteristics of Hudson Bay.