Anthropogenic influence on the autumn migration of polar bears (Ursus maritimus) in Hudson Bay

• Author / Creator

  Miller, Erin

• Migratory species may shift established spatiotemporal patterns in response to anthropogenic impacts, so understanding the energetic consequences of behavioural plasticity may provide insight into how effectively migratory species respond to climate change. I used satellite telemetry to examine individual variation and trends in the autumn migration of 151 adult female polar bears (Ursus maritimus) in western Hudson Bay, Canada from 1991 to 2020. I used regressions and time-to-event models to assess biological and environmental factors that influence migration phenology at the end of the terrestrial fasting period. To quantify vulnerability to an increasing fasting period, I examined the energetics of 136 females with offspring. I found that the timing of on-ice departure was delayed in older bears and, not unexpectedly, in years with later sea ice freeze-up. I also found temporal trends in past sea ice dynamics, a northward shift in the distribution of on-ice departure of 2 km/year, and declining energetic stores for females with first-year cubs, with an estimated 67% of females with offspring that would likely have to cease lactation before their on-ice departure date or risk starvation while 20% still risk starvation having ceased lactation. The analysis of migration phenology, however, does not permit insights into the influence of direct human interactions on the spatiotemporal patterns of bears. Therefore, I used satellite eartag telemetry deployed on 50 polar bears in 2016 – 2020 that were caught by Manitoba Conservation Offices as part of the Polar Bear Alert Program near Churchill, Canada and relocated upon release. This methodology allowed for the analysis of movement patterns and recidivism rates to improve our understanding of human-bear conflict mitigation. I found sex differences in the on-ice departure date, with females departing a mean 12 days earlier in the season than males. I found that bears involved in conflict changed their spatial migratory patterns, departing a mean of 104 km further north than non-conflict bears. Multinomial logistic models revealed that bears released later during the migratory period were less likely to re-enter a community at a rate of 8% per day. Polar bears exhibit complex patterns in migration due to the interplay between individual attributes, individual behaviour, and seasonally dynamic sea ice habitat, which are further complicated by the effects of climate change and human-wildlife conflict. As such, the management and conservation of polar bears will require a holistic approach that considers these factors.

• Subjects / Keywords

  • polar bear
  • Arctic
  • phenology
  • human-wildlife conflict
  • sea ice
  • Ursus maritimus
  • climate change
  • migration

• Graduation date

  Spring 2022

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-2hjy-tw29

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.