Tag Archives: breakup

New paper updates lack of trend in W Hudson Bay breakup/freeze-up dates to 2015

A newly-published paper shows that there has been no trend in the time Western Hudson Bay polar bears spent onshore between 2001-2015 due to sea ice conditions at breakup or freeze-up (previously available to 2010 only), despite the marked decline of global sea ice since 2007.


Figure 3 from Castro de la Guardia (2017) showing freeze-up and breakup dates and ice-free days 1979-2015 for Western Hudson Bay. Figure with caption is copied below, with explanation of symbols.

Previously, a 2007 paper by Eric Regehr and colleagues for WHB bears up to 2004, which was used to support the US bid to list polar bears as ‘threatened’ with extinction, concluded that between 1984 and 2003, bears were spending 3 weeks long onshore than they did in the 1980s.

The big news from Castro de la Guardia (2017) is that polar bears spent longer onshore from 1979-2015 by … 3 weeks. That is, no change from the situation in 2004. Wow!

Note the population size of the entire WHB subpopulation has also not declined since 2004 and is currently estimated at about 1030, based on a 2011 aerial survey (Stapleton et al. 2014).

Thanks to Andrew Derocher for the heads-up tweet.

From the abstract (my bold):

We found that the ice-free period in this region lengthened by 3 ± 0.8 wk over the period 1979−2015. Polar bears migrated onshore 2 wk earlier and offshore 1 wk later in the period 2005−2015 than in 1980−1989.

Here is the region in question, illustrated by Fig. 1 from the paper:

castro-de-la-guardia-et-al-derocher-2017-fig-1a-locationThe significant information contained in this paper is breakup and freeze-up dates and length of the ice-free period data for 2010-2015, which has been unavailable until now. More excerpts and comments below, including Figure 3 with its caption. Continue reading

W. Hudson Bay had 1030 polar bears at last count and that is the official number

The IUCN Polar Bear Specialist Group, the IUCN Red List, and Environment Canada (see below) agree that the population size of Western Hudson Bay subpopulation is 1030 or about 1000 bears, based on surveys conducted in 2011.


For the last few months (most recently, here and here), Andrew Derocher has been telling anyone who will listen that that the number is 800. And no one challenges him – not a single reporter asks where the number comes from, not a single research colleague who knows the truth has publicly stated that Derocher is spreading misinformation.

UPDATE 16 December 2016, half an hour after posting: Add The Atlantic to those accepting Derocher’s misinformation on WHB polar bear numbers without question, and failing to see that because patrols in Churchill were stepped up considerably after a serious mauling occurred in 2013 (because several bears got through their Halloween dragnet), more “problem” bears in Churchill since then only mean the Polar Bear Alert folks are doing their jobs.

But what does The Atlantic conclude, after talking to Derocher?

The Churchill bears…are probably doomed.

Never was a rational book on the science and conservation status of polar bears more desperately needed – it will be available soon.
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Add human graves to the list of things that attract polar bears to communities

A report last week that a polar bear dug a human cadaver out of a coffin buried in the cemetery on the west coast of Hudson Bay did not get the media attention it perhaps deserved: it takes the term ‘grisly’ to a new level.

Early arrival of polar bears at Nunavut hamlet prompts early monitoring: One bear digs into burial plot at Arviat cemetery (NunatsiaqOnline, 29 August 2016).


Quotes from the story, a map, and comments on problem bears below.
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Polar bears off the ice in W. Hudson Bay are “well fed and in great shape” this year

Churchill_Polar_Bear_2004-11-15 Wikipedia

Reports from Seal River, just north of Churchill at Churchillwild, at July 26 were crowing about seeing lots of bears onshore, with a veritable beehive of activity the weekend of 16/17 July:

“This has without a doubt been Churchill Wild’s most spectacular start to the summer polar bear watching season. …Bear numbers are up spectacularly this year and all are looking very fat and healthy, perhaps much to the chagrin of climate change “experts.” Our best day for the seductive white carnivores over the past week featured 21 polar bears sighted between the Lodge and our whale swim spot!

The ice pack, which was still visible a week ago [i.e, 17 July or so], has finally dissipated and pushed a large number of bears on to our coastline here at Seal River, with the end result being many very happy cameras!” [my bold]

And in Churchill proper, the Polar Bear Alert program has issued three reports so far this season (courtesy the Town of Churchill), which confirm that bears in the Polar Bear Capital of the World are also in great shape.

For the week of July 11-17, 2016:

“Bears are off the sea ice and on land. They are looking well fed and in great shape.”

See all three PBA reports below, compared to one from last year at this time (as well as a map and some ice charts).

More fat, healthy bears than last year, enough to keep the Polar Bear Alert folks hopping and tourists in the north happy. Sure doesn’t sound like a suffering population to me. Continue reading

Sea ice habitat Canada update for 23 July 2016 vs. 2014 & the start of bear problems

Sea ice breakup is always a little bit different year to year but since I have the maps archived, take a look at the differences and similarities at this date for this year compared to 2014…

Sea ice extent Canada 2016 July 23_CIS

Sea ice extent Canada 2014 July 23 CIS

Is there evidence that any polar bears – say Western Hudson Bay bears, for example – were negatively affected by sea ice levels in 2014? Not that I’ve heard. In fact, quite the opposite.

Polar bear guide and blogger Kelsey Eliasson, writing from Churchill, Manitoba, had this to say about the condition of bears and freeze-up that year (16 Nov. 2014):

“With these families appearing [heading out to the ice], it really sums up at just what a productive season this has been for the western Hudson Bay population. Any guide who knows their stuff will tell you this was a banner year for cubs, one we haven’t seen in a long time.”

Meanwhile, bears are starting to come ashore and cause a bit of grief:

Southern Hudson Bay (two days ago): “Polar bear shot after wandering through Kashechewan” [see map below for location: the bear shot was a cub that appears to have been separated from its mother and sibling, who were spotted several km away not causing any trouble]

Iqaliut, Baffin Island (this morning): “Polar bear rips 6 tents pitched in Iqaluit park”

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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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Polar bears and W. Hudson Bay sea ice breakup 2016

Breakup for Western Hudson Bay (WHB) is looking to be later than usual this year, given that the average breakup date since 1991 has been July 1 (using a 30% threshold) – only a few days from now – and the ice in WHB is nowhere near 50% coverage, let alone 30%.

Churchill_Polar_Bear_2004-11-15 Wikipedia

Note that few WHB bears come off the ice around Churchill – most come ashore along the southwest coast of Hudson Bay (almost into SHB) and make their way north over the course of the summer to meet the ice as it reforms in the fall north around Churchill – that’s why it’s called a “migration.”


There’s still a lot of ice left in Hudson Bay, as the Canadian Ice Service map for 29 June 2016 (below) shows: Sea ice extent Canada 2016 June 29 CIS

It seems to me that breakup for WHB this year is looking rather like 2014, which was something like a week later than the average since 1991, but time will tell. See below for comparison to 2009 (a late breakup year), 2015, and 2013 (lots of variability!), as well as a discussion of when bears come ashore in relation to this sea ice breakup benchmark.

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