Polar bears have begun to come back ashore on Western Hudson Bay – Watts Up With That?

From Polar Bear Science

Posted on July 9, 2021 | 

So far, the first evidence I’ve seen of a bear ashore in Western Hudson Bay was one photographed near Churchill Manitoba on 28 June (below).

28 June 2021 near Churchill

However, by 5 July, the first of six collared females from Andrew Derocher’s WH study (below) had also come ashore, as did others along the shore of Wapusk National Park. This is not ‘early’ – just earlier than the last few years. Like last year, however, there is still a fair amount of sea ice left on the bay and some bears seem to be choosing to stay out longer on what ‘experts’ describe as unsuitable habitat. As you can see on his bear tracker map, Derocher uses a filter that shows only ice >50% concentration because he and his buddies have decided that bears so dislike anything less that they immediately head to shore as soon as ice levels fall below this threshold.

While Derocher’s own data since at least 2015 have shown this is not correct (both on Hudson Bay and elsewhere), he and his colleagues still insist this is the pattern that should prevail (and which they use in their models), a topic which I discussed last year (with references).

Little wonder that the W. Hudson Bay polar bears are heading for land. Very little ice left. Band of ice off the coast of Ontario commonly occurs & allows some bears to stay offshore longer. pic.twitter.com/VDdCjWxdwQ— Andrew Derocher (@AEDerocher) July 6, 2021

There is actually a lot more ice on the bay than shown in Derocher’s tracking map: see the chart from the Canadian Ice Service below:

The ice that’s still on the bay is primarily thick first year ice > 1 m. thick (below), which is less than there was last year at this time but nowhere near any kind of catastrophic level (which would have been no ice at all throughout all of May):

Bear captured on film chilling out near Churchill on 5 July 2021:

Apparently two sets of mothers with one cub were spotted the same day (5 July) on the shore of Wapusk National Park just south of Churchill, captured by the Explore.org live cam (the photos are blurry because the camera is very far away from the beach):

Another single bear was spotted the next day (6 July):


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