Tag Archives: late freeze-up

Hudson Bay freeze-up 2014 – average again this year, not late

Freeze-up of Hudson Bay sea ice is well underway now, virtually the same time as it was the last three years, and in 2008. Bears in the north will be able to move out, while near Churchill and in Southern Hudson Bay, some bears will be able to successfully hunt for seals on the newly-formed ice close to shore.

Over the next week or so, all the bears onshore will gradually move out onto the ice as freeze-up progresses. By the time there is ~10% ice coverage on the bay, most bears will have moved onto the ice (except pregnant females that have made dens onshore).

The Arctic outbreak underway in over North America may hasten this process along (see 7-day and 14-day weather forecasts for Churchill). Ice maps below courtesy Canadian Ice Service.

Sea ice extent Canada 2014 Nov 13 CIS

It seems pretty clear now that time of freeze-up on Hudson Bay is not correlated with the extent of sea ice at the September minimum. Have a look at the maps and graphs below.  UPDATE: more recent maps added below (ice concentration 15 November; ice development 14 November).
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Natural selection helps polar bears adapt to sea ice variability – which means some bears die

Evolution is not just for the long-term – natural selection also goes on over short time periods. In the case of polar bears, this adaptation is almost certainly critical for its long-term survival.

Hudson Bay female with cub_Wapusk_Thorsten Milse_Gov CA

Hudson Bay female with cub Wapusk National Park, Thorsten Milse, Government of Canada

Not all polar bears are identical — that is the reality that allows natural selection to operate.

I will argue that early breakup years in Western Hudson Bay weed out individual polar bears that do not have the physiological or behavioral characteristics necessary to be useful members of the population – and that this is a good thing for the entire population.

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