Tag Archives: Hudson Bay

Four years of PolarBearScience and polar bear habitat for ‘Christmas in July’

The traditional gift for a 4th anniversary is flowers, so to celebrate 4 years of blogging at PolarBearScience, I’m highlighting a CBC article from last year that featured the work of photographer Dennis Fast, who captured some fantastic images of polar bears cavorting in a field of fireweed near Churchill (see screencap below from the 2015 CBC feature, more at the DailyMail for 21 August 2015). Great photography – it deserves another look.

Churchill pbs in wildflowers_CBC feature_August 2015

Hard to imagine that four years have passed! Cheers to Hilary Ostrov (who blogs at The view from here) for getting me over my initial frustrations with WordPress – without which I’d never have made it this far – and for her much-appreciated typo alerts [Hilary is still dealing with on-going health issues but we talk on the phone from time to time.]

And thanks of course to my readers, who’ve made it all worthwhile. I truly appreciate all your tips and feedback. The word is getting out, via tweets and retweets, reblogging, personal blog and Facebook discussions, as well as links back to particular posts in the comments of news articles and other internet content, and straight up media mentions. The sum of it all has brought us to this point: 495 posts, over 764,000 views, and more than 411,000 visitors. Not too shabby for a single issue science blog, eh?

I thought of adding a Tip Jar button for next year, but decided against it – instead, if you’d like to support my efforts here, you can buy my polar bear attack novel (give it as a gift if you’re not keen on this type of fiction). I’d be just as grateful. See the sidebar for the link.

But back to business – below find sea ice maps of polar bear habitat at 25 July (‘Christmas in July’), this year as well as some previous years.
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Hudson Bay update – lots of sea ice well positioned for polar bears to get ashore

There is slightly less ice this year in Hudson Bay than last year but it is hugging tight against the western shore, which means polar bears in Western and Southern Hudson Bay will be able to stay out on the ice (if they want to) until August.

Sea ice extent Canada 2016 July 15_CIS

The latest weekly ice graph from the Canadian Ice Service (for 9 July) below shows average ice coverage this year (and more than there was in 1976 and 1977):

Hudson Bay same week 9 July 1971-2016

[By the way, the IUCN Polar Bear Specialist Group website is still “under construction” allowing them to avoid mentioning the less-than-dire conclusions contained in the 2015 IUCN Red List assessment]

More ice maps below, comparing previous years.

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Five years of polar bear habitat at June 20 around the Arctic

Five years worth of sea ice maps for the same date is hard to come by in this country, since the Canadian Ice Service does not archive their daily sea ice maps. However, due to some forethought, I have at hand ice maps going back to 2012 for the longest day of the year for Canada and archives for other regions provide similar perspective at the solstice.

Polar_Bear_male on sea ice_Regehr photo_March 21 2010_lg

Few photos of polar bears in June likely exist – too early for most bears to come ashore and the ice too unstable for humans to be offshore [photo above is dated March].

Compare the five maps for Canada and eastern Alaska below. Notice the differences for Hudson Bay: it may seem ironic, but 2012 (which had the lowest September minimum since 1979 due to an August storm) had the most typical Hudson Bay breakup/melt pattern compared to previous years. [Keep in mind this recent post about how much ice can remain even when almost none is visible on the ice maps]

In many regions, polar bear hunting efforts are seldom successful after early June because young-of-the-year seal pups have taken to the water to feed, which means the only prey still on the ice are predator-savvy adults and subadults that have an easy time escaping in the rapidly breaking up ice fields. Bears that come ashore in June likely are not missing much – a little less ice than usual at this time of year is not going to make much difference.

Overall, despite doom and gloom predictions we heard in March 2016 (“wintertime extent hits another record low”), sea ice extent (courtesy NSIDC) at 20 June 2016 was the same at this date as it was in 2010 and 2012 at this time of year – which essentially marks the end of the primary feeding period for polar bears (except for those that live in the Canadian Arctic Archipelago, where seals give birth a bit later in the spring).

Sea ice at 20 June_2016 vs 2012 and 2010_NSIDC interactive

And did polar bears die in droves due to conditions in 2010 or 2012, in any subpopulation around the Arctic affected by low sea ice levels? No, they did not. In fact, the subpopulation that had the most recent survey done (Svalbard portion of the Barents Sea – 2015) was not only found to be thriving but numbers had increased markedly (42%) over 2004 levels. Now that’s resilience!

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More polar bear habitat in Hudson Bay region at mid-May than in 2006 & 2011

What a difference a bit of historical perspective can make to one’s attitude on the annual Arctic sea ice breakup.

masie_all_r10_v01_2016137_4km

The usual recent pattern (since 1979) has been for breakup to begin on the east side. However, this year and last (below), it has begun in the NW (as it did in 1990 and a few other years).

Not all of the open water is due to melt, of course. As I discussed last week in relation to the Southern Beaufort Sea, winds and prevailing currents at this time of year start to fracture the ice and move it around well before much significant melt has begun.

Compare 2016 (above) to 2006 (below), when there was 0.1 mkm2 less overall – with much less ice in Hudson Strait and in the east of Hudson Bay than this year:
masie_all_r10_v01_2006136_4km

Compare to 2011, when there was also 0.1 mkm2 less overall than this year:
masie_all_r10_v01_2011136_4km

It’s important to keep in mind that the intensive feeding season for polar bears is drawing to a close – within another two weeks, most young-of-the-year seals will be in the water feeding and inaccessible to bears.

The only seals on the ice during June and July are predator-savvy adults and subadults that have hauled out to moult and for these seals the rapidly disintegrating ice creates many escape routes. That means that as long as the ice breakup sequence allows polar bears to get their fill of young seals before the end of May, even during early breakup years most bears should be fat enough to survive the coming summer and winter fasts (see more here). So we should expect to see some bears coming ashore within the next two weeks.

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Longest-swimming polar bear lost less weight than if she had stayed onshore

Recent media hype over swimming polar bears in the Southern Beaufort has been quite spectacular (still going strong today at the Washington Post here) but a close look at relevant data shows the message is bogus. Researchers admit (in their methods section) they couldn’t tell if bears said to have swum “non-stop” actually hauled out for half a day or more to rest on small ice flows invisible to satellites and astonishingly, the bear getting all the media attention – who swam the longest of any bear – lost less weight than a bear would have done simply sitting on shore for the same length of time.

Washington Post_swimming polar bears_snapshot 21 April 2016

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Most Beaufort polar bears swim from ice floe to floe during breakup, study shows

swimming3_USGS

You may have seen the headlines in Canadian news outlets over the last 2 days.
“Polar bears swimming farther as sea ice recedes, study shows”

“Melting sea ice forces polar bears to swim longer, farther: study”  [“Bear biologist Andrew Derocher says the forced swims are particularly hard on mothers with young cubs”]

“Polar bears swimming longer, farther because of melting sea ice, study finds”

Oddly, none of the above news reports said where the paper was published or mentioned the name of the lead author – only University of Alberta co-author Andrew Derocher was interviewed (see the only press release I could find here, issued by the San Diego Zoo where the lead author is now employed).[update: CBC ran another story a day later that corrected these omissions]

But what did the study actually say?

Significantly, no bears died while swimming during the two lowest sea ice extent summers since 1979 and no evidence was presented that swims were “particularly hard on mothers with young cubs.” The quotes from the paper below sum it up for Beaufort Sea (BS) bears (the inclusion of Hudson Bay (HB) bears in this study seems gratuitous and potentially misleading, since only a few swam anyway – only 15 out of 59):

“….91% (91/100) of the swims in the BS occurred before the annual September minimum sea ice extent had been reached.  In the BS, 81% (29/36) of swims started and ended in pack ice…

So, despite what may be implied during media moments, Beaufort Sea polar bears were  not frantically trying to reach the sea ice from land so that they could attempt to keep feeding over the summer – most of their swimming was done during breakup in July and August from one bit of pack ice to another and they showed no evidence of harm from doing so. Map from the study and more quotes below.
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Hudson Strait and Davis Strait polar bear habitat highest since 1993

Sea ice development over Hudson Bay, Hudson Strait, and Davis Strait has been rather unusual this year but what that might mean for polar bears over the coming winter and spring is hard to tell.

Canadian Arctic Dec 11 2015_CIS

Note: The Canadian Ice Service seems to be in the process of updating its sea ice page and graphing features that used to be available weekly on Thursday have not been available until the following week. This means the most recent graphs available are for the week of 11 December (see below).
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