Tag Archives: breakup

W Hudson Bay polar bears won’t have an early breakup year, according to sea ice charts

There is still a huge swath of highly concentrated thick first year ice (>1.2m) over most of Hudson Bay this week (19 June 2017) and even in the NW quadrant (the closest proxy we have for Western Hudson Bay), the weekly graph shows levels are greater than 2016, when WHB bears came off the ice in good condition about mid-July. All of which indicates 2017 won’t be an early sea ice breakup year for WHB polar bears.

Hudson Bay weekly ice stage of development 2017 June 19

There is thick first year ice (>1.2m, dark green) in patches along the west coast in the north and south. Thick first year ice also extends into Hudson Strait and Baffin Bay, with some medium first year ice (0.7-1.2m thick, bright green) along the central and southern coasts of WHB.  Note the red triangles incorporated into the thick ice of Hudson Strait in the chart above: those are icebergs from Greenland and/or Baffin Island glaciers. A similar phenomenon has been noted this year off northern Newfoundland, where very thick glacier ice became mixed with thick first year pack ice and were compacted against the shore by storm winds to create patches of sea ice 5-8 m thick.

Compare the above to what the ice looked like last year at this time (2016 20 June, below). There is more open water in the east this year (where few WHB bears would likely venture anyway) but less open water around Churchill and Wapusk National Park to the south than there was in 2016:

Hudson Bay ice age weekly at 20 June 2016

We won’t know for several more weeks if most WHB bears will come ashore at about the same time as last year (early to mid-July) or whether they will be in as good condition as they were last year (because winter conditions may not have been similar).

But so far, sea ice conditions are not looking as dire as the weekly “departure from normal” chart (below, 19 June 2017) might suggest (all that “less than normal” red and pink, oh no!!):

Hudson Bay weekly departure from normal 2017 June 19 Continue reading

Breakup of sea ice on track in Canada as critical feeding period for polar bears ends

Relative to recent years and potential impacts on polar bear health and survival in Canada, there is nothing alarming in the pattern or speed of sea ice breakup for 2017, either over Hudson Bay, the southern Beaufort, or the eastern high Arctic.

Sea ice Canada 2017 June 8

Last year at this time (see map below), there was more open water in Hudson Bay and in the Southern Beaufort yet the polar bears came ashore in fine shape that summer and there was no hue-and-cry of dying bears anywhere. Breakup this year is on track to be about 3 weeks earlier than it was in the 1980s, as it has been since at least 2001, a conclusion reached by polar bear specialists (Castro de la Guardia et al. 2017; Lunn et al. 2016), who examined sea ice breakup to 2015.

Sea ice extent Canada 2016 June 8 CIS

Here are critical words to remember (more details here) from biologist Martin Obbard and colleagues (2016:29) on the relationship between body condition and sea ice for Southern Hudson Bay (SH) polar bears, which apply equally well to bears in other regions:

Date of freeze-up had a stronger influence on subsequent body condition than date of break-up in our study. Though models with date of freeze-up were supported over models with other ice covariates, we acknowledge that lower variability in freeze-up dates than in ice duration or break-up dates could have influenced the model selection process. Nevertheless, we suggest that a stronger effect of date of freeze-up may be because even though break-up has advanced by up to 3-4 weeks in portions of Hudson Bay it still occurs no earlier than late June or early July so does not yet interfere with opportunities to feed on neonate ringed seal pups that are born in March-April in eastern Hudson Bay (Chambellant 2010). Therefore, losing days or weeks of hunting opportunities during June and July deprives polar bears of the opportunity to feed on adult seals, but does not deprive them of the critical spring period (Watts and Hansen 1987) when they are truly hyperphagic. No doubt, the loss of hunting opportunities to kill adult seals has a negative effect on body condition, but it appears that for bears in SH a forced extension of the fast in late fall has a greater negative effect on subsequent body condition.” [my bold]

In other words, by mid-June at least (maybe earlier), polar bears have largely finished their intensive feeding that’s so critical to their survival over the rest of the year.

That’s why the latest count of SH polar bears (Obbard et al. 2015) showed a stable population (and see this recent post on WHB polar population estimates). But freeze-up was late last year and that’s what will make the difference to polar bears over the coming year.

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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.

castro-de-la-guardia-et-al-derocher-2017-fig-3-no-caption

Figure 3 from Castro de la Guardia and colleagues (2017) showing freeze-up and breakup dates and ice-free days 1979-2015 for Western Hudson Bay. Figure with caption, copied below, explains 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 longer onshore than they did in the 1980s.

The big news from Castro de la Guardia et al. (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.

western-hudson-bay-surveys-2011-compared_polarbearscience-16-dec-2016

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).

mother-and-cub-on-beach_Stirling

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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