Polar bear diet composition reveals spatiotemporal distribution of Arctic marine mammals across Nunavut, Canada

• Published in: Ecological Indicators
• Main Authors: Melissa P. Galicia, Gregory W. Thiemann, Markus G. Dyck, Steven H. Ferguson
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2021
• Subjects: Polar bears; Arctic; Marine mammals; Diet; Spatial distribution; Quantitative fatty acid signature analysis (QFASA); Ecology; QH540-549.5; Nunavut; Hudson Bay; Baffin Island; Canada; Hudson; Foxe Basin; Southampton Island; Jones Sound; Melville Sound; Viscount Melville Sound; Gulf of Boothia; Arctic marine mammals; Baffin; bearded seal; Beluga; Beluga whale; Beluga*; Davis Strait; Delphinapterus leucas; Erignathus barbatus; harbour seal; Harp Seal; Monodon monoceros; narwhal*; Odobenus rosmarus; Pagophilus groenlandicus; Phoca vitulina; Pusa hispida; ringed seal; Ursus maritimus; walrus*
• Online Access: https://doi.org/10.1016/j.ecolind.2021.108245; https://doaj.org/article/66e810957203458080189e7358a79ba7

Climate warming and associated physical and biological changes will likely force widespread species redistribution, particularly in polar environments. However, tracking such distributional shifts is difficult. The dietary habits of apex predators, like polar bears (Ursus maritimus), may provide early signals of distributional change in prey populations. We used harvest-based sampling to investigate the spatial feeding patterns of polar bears across Nunavut from 2010 to 2018 (n = 1570) and identify spatiotemporal clusters of different prey based on predator diet estimates. Quantitative fatty acid signature analysis and the Getis-Ord Gi* statistic identified spatial clusters of high or low dietary proportions (i.e., “hot spots” and “cold spots”) reflecting seasonal and spatial availability of prey. Ringed seal (Pusa hispida) was the primary prey of bears throughout Nunavut followed by bearded seal (Erignathus barbatus), although proportional consumption varied spatially. A consistent ringed seal consumption hot spot was found in Gulf of Boothia indicating the importance of year-round availability of ringed seals. Spatial clusters of bearded seal and Atlantic walrus (Odobenus rosmarus rosmarus) throughout Foxe Basin suggested overlapping seasonal distributions and high regional abundance. Bears had consistently high dietary levels of harbour seal (Phoca vitulina) around Southampton Island and along the western coast of Hudson Bay suggesting a possible year-round concentration of this prey. Hot spots of harp seal (Pagophilus groenlandicus) consumption were evident throughout Davis Strait and a spring-summer hot spot around Jones Sound was consistent with harp seal migratory patterns. Year-round beluga whale (Delphinapterus leucas) hot spots were found along eastern Baffin Island and southern Viscount Melville Sound providing new knowledge of local conditions that promote polar bear predation or scavenging. Narwhal (Monodon monoceros) were less susceptible to predation with only one spatial cluster of high ...