Migration dynamics of polar bears (Ursus maritimus) in western Hudson Bay

• Author / Creator

  Bohart, Alyssa Mary

• Migration is a behavioral response to temporal variation in resources. While migration phenology is often predictable, phenology is expected to shift as climate change alters seasonal resource availability. We used data from satellite-linked telemetry collars on adult female polar bears (Ursus maritimus) in western Hudson Bay from 2004-2016 to: (1) quantify migration using multiple metrics, (2) assess environmental and biological factors that may influence migration, and (3) evaluate temporal patterns in migration. We included migration metrics (maximum distance to coast, Brownian bridge home range size, median speed (km/h), straightness index, land departure date, and land arrival date) as response variables in multivariate response variable regression models to assess the effect of environmental (ice concentration, wind speed, and wind direction) and biological (bear body condition, bear age, age of offspring, and number of offspring) factors on migration. We included year as a covariate to assess temporal effects on migration. We found that ice concentration was the only factor that consistently predicted migration patterns. Wind direction and wind speed were predictors of freeze-up migration, whereas wind direction was a key predictor of break-up migration. Migration patterns did not change temporally, suggesting lack of a climate-induced migration shift. Examining multiple migration metrics avoids oversimplification of a complex behavior and allows an in-depth investigation into what factors influence migration.

• Subjects / Keywords

  • polar bear
  • migration

• Graduation date

  Spring 2020

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-0r2d-8s26

• License

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