Abstract
The Cape Bathurst polynya and flaw lead (CBP) are major, predictable habitat features with ≤15% ice cover in an otherwise ice-covered Beaufort Sea, and thought to provide hunting opportunities for polar bears (Ursus maritimus Phipps, 1774). We assessed 78 adult (female; with and without cubs) and subadult (male and female) polar bears’ use of the CBP from October to June 2007–2014. The CBP was up to 725 km wide in autumn, ice-covered in winter, and <306 km wide in spring. Seventy-nine percent (n = 62) of the bears used the CBP (≥1 location <2.4 km, or one 4 h step length, from the CBP). Use was higher for solitary adult females and subadult males, which travelled faster with low turning angles along wider sections than females with offspring and subadult females. Bears were closest to the CBP during the spring hyperphagia season. Although a wider CBP did not prevent crossing, bears primarily crossed from the coast towards pack ice at locations 53% narrower than areas not crossed. Bears might avoid crossing when it would require a long-distance swim. The CBP affects polar bear ecology by providing hunting habitat and a corridor that could increase prey encounters but may affect movement.
Highlights
Polynyas are recurrent areas that are predominantly or completely ice-free in an area otherwise ice-covered (Smith et al 1990), while flaw leads are recurrent, linear ice-free areas between landfast ice and pack ice (Barber and Massom 2007)
The Cape Bathurst polynya and flaw lead (CBP) forms in the Amundsen Gulf between Baillie Island and Banks Island (Stirling 1980; Smith and Rigby 1981) with the associated flaw lead extending northward and westward (Fig. 1) and can be open any time there is ice cover, but is most prominent beginning in April (Smith and Rigby 1981)
We found spatial and temporal variation, influenced by reproductive status, in the use and selection of the CBP and in polar bears movements relative to the features
Summary
Polynyas are recurrent areas that are predominantly or completely ice-free in an area otherwise ice-covered (Smith et al 1990), while flaw leads are recurrent, linear ice-free areas between landfast ice and pack ice (Barber and Massom 2007). They occur throughout the Arctic and are ecologically important due to their high primary productivity and provision of habitat to a diversity of species (Stirling 1980; Arrigo and van Dijken 2004; Laidre et al 2008). 1774) (Stirling et al 1981; Gilchrist and Robertson 2000; Citta et al 2015; Mallory et al.2019).
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