Polar bears of western Hudson Bay still on the ice at third week June

According to the tracker map provided by Andrew Derocher (University of Alberta), all of the western Hudson Bay polar bear females that still have operational satellite collars (deployed in 2019) are still out on the ice of Hudson Bay. The Explore.org live video cam that sits on the shore of Wapusk National Park just south of Churchill has been capturing images of caribou and birds but so far, no polar bears. Last year, the first bear seen onshore by the cameras (shown in the video) was on 13 July.

It wasn’t until a month later that more bears were seen: the fat mother and cub in the screencap below were spotted on 18 July 2020 and the last of the collared bears didn’t come ashore until late August:

This year at 21 June, only 6 collars still operating but only one of them is anywhere close to shore yet (courtesy Andrew Derocher via twitter, below):

That ice in the middle of the bay is still primarily very thick first year ice, as the chart for this third week of June shows (below):

Sea ice stage of development for the week of 21 June 2021, where dark green is thick first year ice > 1.2 m thick:

Compare the tracking map above to those from previous years that I have in my archive, below. Derocher usually posts these once a week.

2020 (19 June):

2019 (29 June, a week later than this year):

2018 (24-25 June):

2015 (22 June), notice how many bears were still out on the ice by the third week of June (although two were onshore):

And here is Derocher from 1 June 2015 suggesting that 2015 might be the earliest WH breakup on record (spoiler alert, it wasn’t even close – see graph below):

From Castro de la Guardia (2017), the earliest breakup date (most bears onshore) was 9 June 1999 (middle panel):


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/

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