Using spatial autocorrelation to quantify the effects of sea ice fragmentation on polar bear movement in Hudson Bay

• Author / Creator

  Biddlecombe, Brooke

• Habitat fragmentation occurs when continuous habitat gets broken up as a result of ecosystem change. While commonly studied in terrestrial ecosystems, Arctic sea ice ecosystems also experience fragmentation, but are rarely studied in this context. Most fragmentation analyses are conducted using patch-based metrics, which are potentially less suitable for sea ice that has gradual changes between sea ice cover values, rather than distinct patches. Thus, using an integrated step selection analysis, I compared the predictive power of a patch-based metric to a more novel metric, the variation in local spatial autocorrelation of sea ice cover over time. I used satellite telemetry data from 39 adult female polar bears (Ursus maritimus) in Hudson Bay to examine the relationship between bear movement and their sea ice habitat using Advanced Microwave Scanning Radiometer 2 data during sea ice break-up in May through July from 2013-2018. Spatial autocorrelation resulted in better model fits across 64% of individuals, although both spatial autocorrelation and patch-based metrics were more effective in predicting movement patterns than habitat selection. After determining the effectiveness of spatial autocorrelation for quantifying fragmentation, I used this metric to explore individual variation in multiple aspects of polar bear migratory movement to land during break-up. In late break-up, bears that moved through habitat with higher variability in spatial autocorrelation of sea ice cover were correlated with increased path tortuosity. As well, individuals arrived on land significantly later as paths in late break-up moved through sea ice with increasing variation in spatial autocorrelation. Reproductive status of adult female polar bears had no effect on the variability of sea ice an individual travelled through. Variation in spatial autocorrelation of sea ice provides a means of summarizing a complex and dynamic habitat and can be used to understand individual variation in polar bear movement and ecology.

• Subjects / Keywords

  • integrated step selection analysis
  • polar bears
  • habitat fragmentation
  • sea ice
  • ecology

• Graduation date

  Spring 2020

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-93ke-c420

• License

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