Tag Archives: hunting

Western Hudson Bay polar bears on their way offshore to hunt seals: freeze-up has begun

Official confirmation has come in this morning that polar bears that have spent the summer fasting along Western Hudson Bay now have enough ice to move offshore. That makes this year a bit later than usual (average is 16 November) but is not one of the extremely late freeze-ups, as happened in 1981, 2016 and 2021 when bears didn’t leave until the first week of December (Castro de la Guardia et al. 2017; Miller et al. 2022). Since breakup of sea ice came earlier than usual this summer, this means (as of 30 November) many bears will have been off the ice and without food for 166 days or 5.5 months.

However, so far, there have been no reports from this region of incidents of cannibalism, starving bears found wandering the landscape like zombies, or desperate attacks on people that polar bear specialists have warned us to expect (Abrahms et al. 2023; Stirling and Derocher 2012; Wilder et al. 2017).

Tracking WH Bears

Courtesy Andrew Derocher, University of Alberta, who monitors WH bears:

Close-up of the tracking map below. Note that pregnant females will stay ashore to give birth so not all of these tagged bears are expected to head onto the ice this fall to hunt for seals:

Still not a word from the Polar Bear Alert folks in Churchill, who as of today, haven’t released any of their weekly reports since 23 October 2023.

Ice Conditions in Canada

At 30 November 2023, courtesy Canadian Ice Services shows the expanding band of ice developing along the western shore of Hudson Bay but note also that the rest of the Canadian Arctic, as well as the Beaufort Sea, is completely covered in ice, as is most of Baffin Bay and Foxe Basin:

References

Abrahms, B., Carter, N.H., Clark-Wolf, T.J., et al. 2023. Climate change as a global amplifier of human–wildlife conflict. Nature Climate Change 13:224-234. https://doi.org/10.1038/s41558-023-01608-5

Castro de la Guardia, L., Myers, P.G., Derocher, A.E., Lunn, N.J., Terwisscha van Scheltinga, A.D. 2017. Sea ice cycle in western Hudson Bay, Canada, from a polar bear perspective. Marine Ecology Progress Series 564: 225–233. http://www.int-res.com/abstracts/meps/v564/p225-233/

Miller, E.N., Lunn, N.J., McGeachy, D., and Derocher, A.E. 2022. Autumn migration phenology of polar bears (Ursus maritimus) in Hudson Bay, Canada. Polar Biology 45:1023-1034.

Stirling, I. and Derocher, A.E. 2012. Effects of climate warming on polar bears: a review of the evidence. Global Change Biology 18(9): 2694–2706.

Wilder, J.M., Vongraven, D., Atwood, T., et al. 2017. Polar bear attacks on humans: implications of a changing climate. Wildlife Society Bulletin 41(3):537-547.  https://doi.org/10.1002/wsb.783

Polar bear sea ice habitat near the end of Arctic spring 2023

Arctic sea ice is beginning to melt and the end of spring is drawing near. Mating season is over for polar bears as is the gorging on young seals in most regions as weaned pups head into open water to feed for themselves. Only predator-savvy adult and subadult seals remain on the ice while they moult a new hair coat, so successful hunts by most polar bears will become more and more uncommon (e.g. Obbard et al. 2016).

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Birthing season for harp seals in Labrador Sea just in time to feed hungry polar bears

The main birthing period for NW Atlantic harp seals has arrived. Local populations of ringed and bearded seal pups will soon follow but in the Gulf of St. Lawrence in eastern Canada, the pupping season for harp seals that is usually in progress by this time has likely been redirected north due to lack of suitable ice conditions. Sea ice off Labrador and Newfoundland is in good condition and this is where the vast majority of the global population go to give birth (ca. 7.6 million vs. 1.5 million in the White Sea and 434,000 in east Greenland).

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Early-birthing polar bear female with new cubs out on the ice already in Western Hudson Bay

At least a month earlier than in more northerly areas of the Arctic, the first known female with new cubs-of-the-year has been reported on the sea ice hunting for seals in Western Hudson Bay. Remember this when the cries of “early” breakup of sea ice on Hudson Bay come in the summer: these WH bears routinely get a head start on spring feeding that other bears don’t get.

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Polar bears of SE Greenland get shorefast ice necessary to hunt seals: not so unique after all

The 234 or so polar bears inhabiting the SE tip of Greenland, said to be genetically and ecologically unique because they are “surviving without ice“, have been experiencing sea ice formation along the shoreline this month just like other bears across the Arctic. Recall that shorefast ice formation attracts seals in the fall, which polar bears hunt successfully, and the following spring (April/May) provide a platform for ringed seals to give birth to their pups, which polar bears eat with gay abandon.

The photo above was taken by Kristin Laidre in March 2016: a bear this fat at the end of winter (i.e. before ringed seals are born in the spring) is living in productive habitat.

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New polar bear hunting habitat forming already along the coast of the Laptev Sea: A new trend?

Not even three weeks after the yearly minimum of sea ice extent was reached this year, new shorefast ice is already forming off the coast of Siberia, which is critical fall hunting habitat for polar bears.

Polar bears on a seal kill in new ice, 31 October 2020 in W. Hudson Bay via webcam.

So, not only was this year’s sea ice extent for September at the very lowest extreme of predicted levels for late summer, given ever-increasing CO2 concentrations in the atmosphere, new ice seems to be forming earlier in the fall as well, which bodes well for winter ice formation. It’s looking to me like the decade-long increasing trend of September ice extent since 2012 (see below) may indicate a change more biologically relevant to ice-dependent Arctic animals than the zero trend since 2007.

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Sea ice average for March is the metric used to compare to previous winters

The average sea ice cover at the end of March is the metric used to compare ‘winter’ ice to previous years or decades, not the single-day date of ‘most’ ice. This year, March ended with 14.6 mkm2 of sea ice, most of which (but not all) is critical polar bear habitat. Ice charts showing this are below.

But note that ice over Hudson Bay, which is an almost-enclosed sea used by thousands of polar bears at this time of year, tends to continue to thicken from March into May: these two charts for 2020 show medium green becoming dark green, indicating ice >1.2 m thick, even as some areas of open water appear.

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Caught on film: polar bear stalks, kills and eats a Svalbard reindeer but climate change is hardly to blame

The possibility that a polar bear somewhere in the Arctic might occassionally be successful at stalking and killing a reindeer (aka caribou) shouldn’t surprise anyone, let alone a biologist on Svalbard. But having video footage of the event makes it immediately newsworthy, especially when the researchers vaguely suggest that global warming might be to blame.

The title of the scientific paper that has generated the latest polar bear hype is called ‘Yes, they can: polar bears Ursus maritimus successfully hunt Svalbard reindeer Rangifer tarandus platyrhynchus’ (Stempnlewicz et al. 2021).

Would any serious scientist really think they couldn’t?

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Spring polynyas in the Arctic then and now as feeding areas for hungry polar bears

Patches of open water in the Arctic that develop in the spring, including polynyas and widening shore leads, are largely due to the actions of wind and currents on mobile pack ice rather than ice melt. Contrary to concerns expressed about possible negative implications of these early patches of open water, these areas have always been critical congregation areas for Arctic seals and are therefore important feeding areas for polar bears in late spring.

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Podcast with WildFed about polar bears and domestication as speciation

A couple weeks ago I had a fabulous chat with Daniel Vitalis from Wildfed about a wide range of topics, including my work on polar bears and domestication as a process of speciation. The podcast went live this morning – have a listen here (also copied below), I think you’ll enjoy it. One hour, 36 minutes.