Habitat use and movement ecology of polar bears (Ursus maritimus) in western Hudson Bay

  • Author / Creator
    Alexandra Marie Claire Beatty
  • Climate change is altering sea ice phenology, which forces polar bears (Ursus maritimus) to spend an increasing amount of time on land. Therefore, understanding movement ecology and terrestrial habitat selection of bears may become increasingly important for conservation planning. The Western Hudson Bay polar bear population spends ice-free summer months on land. While onshore, terrestrial feeding is minimal, and movements are limited to conserve energy. When the ice-free period ends, bears migrate onto newly forming sea ice. Our research objective was to assess terrestrial movement rate, tortuosity, directionality, habitat selection, and site fidelity of adult female polar bears on land during the ice-free period with locations from satellite-linked telemetry collars deployed on 106 adult female polar bears (2004-2017). The movements of females occupying two different regions were examined to assess the influence of biological and environmental correlates. Individual females had varied movement patterns: 35% moved inland (mean distance from coast = 36 km) before they returned to the coast during freeze-up, 51% of females remained near the coast (mean distance from coast = 11 km), and 14% did not fall into either category. Both interior and coastal females exhibited high path tortuosity possibly reflecting energy conservation, terrestrial feeding, and/or conspecific avoidance. Terrestrial movement rate (mean = 0.15 km/h, range: 0.0-6.25 km/h) was influenced by bear age, windspeed, time of day, days since ice breakup, and distance to coast. Movement rate increased with bear age, presence of daylight, and when bears were closer to the coast, but decreased with increased windspeed. By October, movement rate reached a minimum (mean = 0.08 km/h) and then increased during freeze-up (mean = 0.21 km/h) when bears migrated onto the sea ice. Habitat selection was investigated using telemetry locations from 122 females in 2004-2017 and land cover classes from a high-resolution terrestrial ecosystem map. A resource selection function with Akaike Information Criterion model selection was used to evaluate terrestrial habitat selection within Wapusk National Park, Manitoba, Canada. Females preferred freshwater ponds and riparian areas that provide water. At the population level, during the ice-free period (September to October), females avoided the coast. During freeze-up, females selected for the coast during migration to sea ice. Females exhibited regional site fidelity to western Hudson Bay during the ice-free period, but not site-specific fidelity.

  • Subjects / Keywords
  • Graduation date
    Fall 2020
  • Type of Item
  • Degree
    Master of Science
  • DOI
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