Habitat fragmentation can impede an animal’s ability to move through their habitat, affecting both local and long-distance movements. Each year, polar bears Ursus maritimus migrate to refuge habitats on land or to multiyear ice as annual sea ice breaks up. We used polar bear telemetry location data from 39 adult female polar bears tracked in Hudson Bay in 2013-2018 during break-up (2 May-23 July) to show variation in migratory movement and timing as break-up advances. We separated break-up into early and late periods and used standard deviation in temporal spatial autocorrelation (SASD) of sea ice concentration to quantify sea ice fragmentation. Higher spatial autocorrelation reflects dissimilarity in local habitat composition at a single point in time, while SASD reflects variation in local habitat composition over time. In late break-up, there was a significant positive correlation between polar bear path tortuosity and SASD. Individuals arrived on land significantly later when paths moved through sea ice with increasing SASD in late break-up. Reproductive status of adult female polar bears had no effect on the variability of the sea ice an individual travelled through. SASD provides a means of summarizing the complexity and dynamics of sea ice habitat and can be used to understand variation in movement and ecology of ice-associated organisms.

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Narwhals (Monodon monoceros) are an important subsistence harvest species for Inuit communities and their conservation is important for Inuit culture and ecosystem function. The northern Hudson Bay (NHB) narwhal population, which spends summer in northern Hudson Bay, Canada, has been assessed through periodic aerial surveys from 1981 to 2018. To estimate the population trajectory and predict future population trends under various harvest scenarios, a Bayesian population model was fit to four aerial survey estimates and harvest data from 1951 to 2018. The model resulted in a 2019 population estimate of ~14,400, 95% CI [10,300, 20,400] and an estimated starting population of 7,200, 95% CI [1,400, 19,000] in 1951. The model was extended 10 years into the future under three annual harvest scenarios (current harvest: 157, low harvest: 50, and high harvest: 300) and the probability of population decline was estimated. The model predicted a 6% chance of decline with an annual harvest quota of 50 narwhals, 78% for a harvest of 157, and 95% for a harvest of 300. This updated model provides the opportunity to shape conservation efforts by estimating past population trends and how those trends, combined with management action, can affect future population dynamics.

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, than distinct “long‐term” patches. Using an integrated step selection analysis, we compared the descriptive power of a patch‐based metric to a more novel metric, the variation in local spatial autocorrelation over time. We used satellite telemetry data from 39 adult female polar bears (Ursus maritimus) in Hudson Bay to examine their sea ice habitat using Advanced Microwave Scanning Radiometer 2 data during sea ice breakup in May through July from 2013–2018. Spatial autocorrelation resulted in better model fits across 64% of individuals, although both metrics were more effective in describing movement patterns than habitat selection. Variation in local spatial autocorrelation allows for the visualization of sea ice habitat at complex spatial and temporal scales, condensing a targeted time period of habitat that would otherwise have to be analyzed daily.

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