Polar bear sea ice habitat replace at 15 November & drawback bears in Western Hudson Bay • Watts Up With That?

From Polar Bear Science

Susan Crockford

Abundant polar bear habitat this fall across the Arctic so far, with only Hudson Bay sea ice formation a bit behind schedule. However, Churchill has not seen the anticipated spike in problem bear reports, given the vocal pronouncement by polar bear specialists that it should be experiencing more and more problems with bears when they spent more than 4 months ashore in summer and fall.

News of the most egregious attack by a bear I could find world wide this fall is shown in the video below, filmed 14 November 2023: apparently, the offending bear had spent several days displaying this offending behaviour.

Arctic overall according to NSIDC Masie

Sea ice is forming at least as fast this year as it has for the last two years, despite dubious claims that this year was the warmest in the last 125,000 years.

Current sea ice coverage across the Arctic looks like this:

In regards to thickness, in the chart below dark blue, green, yellow and red indicate perennial ice 1-5m or more that resisted melt this summer while the purple is newly-formed ice this fall, original here:

Hudson Bay

This year most bears came ashore by 17 June when the ice broke up, so by 15 November the bears had been onshore for 152 days or about five months.

The video below was recorded 9 November from a Tundra Buggy and published 11 November 2023, showing that at least one bear must have made a seal kill (although the kill itself was not caught on camera):

If the bears have to wait another 3 weeks for enough ice to do some serious ice-based hunting, that would put them at 173 days or so without food, which is beyond their theoretic limit of endurance of 170-171 days according to the models (Molnar et al. 2020). Based on these predictions, the experts say we should see wide-spread starvation of adult males and females with cubs near Churchill if freeze-up is delayed until 7 December.

However, that now looks unlikely, as the weather has turned very cold in Churchill and that suggests the sea ice will start to form rather quickly over the next week.

And as of 16 November, grey ice (dark purple) had been forming nicely along the northwest coast and in places in Southern Hudson Bay. It seems likely that bears will begin to leave by next week as the new ice (pink) thickens and expands — at most a week about a week beyond the average for the 1980s (i.e., 23 November) after having been ashore for 159 days or so. Still, five months plus one week is an impressive length of time to go without food and without causing much trouble.

In 2022, bears were released from the Churchill jail on 10 November, as early as in the 1980s, because there was enough ice for them to leave. That’s an important metric that the Churchill Alert folks usually announce but not always. They seem to keep more information to themselves than they did a few years ago, including not publishing reports promptly every week as they once did, leaving out weeks worth of reports (e.g. 2022), and not bothering to publish the final few reports of the season (e.g., 2021, 2022).

Reports this year have not been updated since 23 October, so whether we’ll see any more remains to be seen. If the bears had been causing havoc over the last few weeks I’m sure those reports would have been produced promptly and the media alerted: it’s when the bears behave themselves and fail to walk around starving that we don’t hear about it.

Could it be that the Churchill problem bear folks are as invested in maintaining the preferred climate change narrative as activist polar bear specialists and avoid publishing reports that look like good news?

In 2021, freeze-up came a couple weeks later, around 26 November, but as noted above, no problem bear reports were issued after 24 October that year. Within a 2-3 day lee-way, freeze-up was as early in 2020 as some of the earliest years on record (i.e., about 4-7 November, with 1993 the earliest); freeze-up dates in 2017, 2018, and 2019 were about the same as the average in the 1980s or 16 November (de la Guardia et al. 2017; Miller et al. 2022). Significantly Miller and colleagues found no trend in freeze-up dates in their analysis of freeze-up dates to 2020.

This means WH sea ice coverage in the fall has not been “steadily declining” over the last 30 years and polar bear have not been departing for the ice later and later in the season over that period, as many falsely state or imply.

Remember that fall is the second-most important feeding season for polar bears, due to the fact that seals are strongly attracted to newly-forming sea ice. It’s the bears’ chance to regain some or all of the weight lost over the summer, before the long winter fast begins (while bears indeed hunt when they can while they’re on the ice, they are not often successful during the depths of the Arctic winter and most bears are at their lowest weight by March).

This year a litter of triplet cubs was spotted by Explore.org webcams and on 9 November, the family interacted with three other bears near Tundra Buggies full of tourists:


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. https://link.springer.com/article/10.1007/s00300-022-03050-3

Molnár, P.K., Bitz, C.M., Holland, M.M., Kay, J.E., Penk, S.R. and Amstrup, S.C. 2020. Fasting season length sets temporal limits for global polar bear persistence. Nature Climate Change 10:732-738. https://doi.org/10.1038/s41558-020-0818-9

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