Tag Archives: body condition

Chukchi Sea polar bears number almost 3000 according to new survey results

The Chukchi Sea finally has a polar bear population estimate! According to survey results from 2016 only recently made public, about 2937 bears (1522-5944) currently inhabit the region, making this the largest subpopulation in the Arctic. This is exciting news — and a huge accomplishment — but the US Fish and Wildlife Service responsible for the work has been oddly mum on the topic.

beaufort-bears_-suzanne-miller-usfws-3-af-2c-on-spit-1.jpg

Not only that, but an extrapolation of that estimate calculated by USFWS researchers for Chukchi plus Alaska (the US portion of the Southern Beaufort Sea subpopulation) was estimated at 4437 (2283-9527), although with “significant uncertainty.” Nevertheless, it means the 2016 estimate for Alaska could be roughly three times what it was in 2010: a whopping 1500 or so, up from about 450 (or about 225-650) for the same area estimated during the last survey (Bromaghin et al. 2015: Fig. 5a).

Even if the real number for Alaska is only twice as large (~1000), that’s still a huge improvement. It would eliminate the Southern Beaufort as the only polar bear subpopulation in the Arctic to have shown a significant decline blamed on human-caused global warming (Crockford 2018). If the recovery is real, it means the 2004-2006 decline was a temporary fluctuation after all, just like previous declines in the region. I expect, however, that it will take a dedicated SB population survey for officials to concede that point.

There is not yet now a detailed report to cite (Regehr et al. 2018 in prep, see update below), but the numbers were announced at the 10th meeting of the Russian-American Commission on Polar Bears held at the end of July this year (AC SWG 2018) by Eric Regehr (formerly of the US Fish & Wildlife Service, as of 2017 at the University of Washington). [h/t to G.H.] This was the same report that raised the quota for subsistence hunting in the Chukchi from 58 to 85, based on these new figures, as I discussed last week.

Wrangel Island polar bear with cubs 2015 news story

From “Military bases to open on Wrangel Island and Chukotka” 22 October 2015.

Regehr was quoted as saying:

“Chukchi bears remain larger and fatter and have not seen downward trends in cub production and survival, according to new preliminary information on the health and numbers of bears.”

UPDATE 15 November 2018: The scientific paper describing the entirely new method (yes, yet another one: see Bromaghin et al. 2015) used to estimate the size of the Chukchi Sea population is now available (University of Washington press release here), in an open-access paper: Regher et al. 2018. News reports (see one here) spin the positive outcome as something that researchers expected all along but that’s simply not true. They expected Chukchi Sea bears and Southern Beaufort Sea bears to respond similarly to reduced amounts of summer sea ice, as explained here and in Crockford 2017).
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White Lie: Polar bear starvation is virtually never caused by sea ice loss

Starvation due to natural causes is the leading cause of death for polar bears and loss of body condition (getting thinner) is therefore the first symptom of impending death for virtually all polar bears that die naturally. However, polar bear specialist Andrew Derocher claims that loss of body condition is also the first symptom of climate change for polar bears.

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But how do you tell the difference between polar bears made thin by man-made climate change and those who are thin due to natural causes?

You can’t. Even a necropsy will not be conclusive because there are so many natural reasons for a bear to lose weight — and even starve to death — that’s it’s virtually impossible to say that any thin bear is skinny due to a lack of sea ice.

Emaciated polar bears like the one above from Somerset Island in the Canadian Arctic,1 captured on camera in August 2017, are being used to promote the idea that polar bears are already dying of starvation due to climate change. That’s a big white lie, as the headline above suggests: seven months later, National Geographic has admitted as much. Here I show why it could not have been true in the first place (with references from the scientific literature).

UPDATE: 29 August 2018: See my op-ed in the National Post (29 August 2018) and the GWPF video below on this issue:

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Facts contradict predictions that Chukchi Sea polar bears should be in trouble

Last fall, there were persistent alarms raised about low levels of sea ice in the Chukchi Sea that were echoed this spring. But these low ice levels are not really a serious concern for these polar bears: a 2018 assessment found the bears were in excellent health with no declines in cub production or survival. Funny how little we hear about that.

Wrangel Island polar bear with cubs 2015 news story

From “Military bases to open on Wrangel Island and Chukotka” 22 October 2015.

See a photo essay of Wrangel Island here and of the islands polar bears here and here.

You also don’t hear about the fact that sea ice has declined by about the same amount in the Chukchi Sea as in Western Hudson Bay. Since 1979, sea ice in the Chukchi Sea has declined at a rate similar to Western Hudson Bay (-0.90 days per year vs. -0.86 days per year, respectively), see graphs below from Regehr et al. (2016, Fig. 2):

Regher et al. 2016 fig 2 Barents and Chukchi Sea ice declineRegher et al. 2016 fig 2 Wh Bay ice decline

While Western Hudson Bay bear numbers have declined slightly in number (by a non-statistically significant amount) and appear to have suffered some recent declines in cub survival (Dyck et al. 2017) (with unsubstantiated claims of declines in adult body condition), Chukchi Sea bears have not (Rode and Regehr 2010; Rode et al. 2013, 2014, 2018).

The fact that Chukchi bears are thriving while Western Hudson Bay bears appear to be struggling, given almost identical trends in sea ice decline, is a connundrum that polar bear specialist are loath to explain.

Only last week, it was announced that the quota for subsistence hunting of Chukchi Sea polar bears had been raised from 58 to 85 due to the excellent status of the population. Polar bear biologist Eric Regehr was quoted as saying:

“Chukchi bears remain larger and fatter and have not seen downward trends in cub production and survival, according to new preliminary information on the health and numbers of bears.”

So, despite warnings from the polar bear and sea ice “experts” that Chukchi Sea bears may be in dire straits due to recent sea ice declines (see below), it appears that the bears themselves are more resilient to changing conditions than the experts give them credit.

NSIDC sea ice experts cruising the Chukchi Sea took this photo of a polar bear in excellent condition a couple of weeks ago (early August 2018, A. Khan), despite the scary-looking melt ponds:

Chukchi Sea polar bear Arctic_early August 2018_A Khan NSIDC

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Churchill problem polar bear report for week 3, July 23-29 2018

Polar bears that have come off the sea ice of Hudson Bay near Churchill, Manitoba in Western Hudson Bay are apparently in a wide variety of conditions, from very fat to skinny.  So, not all skinny despite the relatively early breakup of ice in the northwest.

Churchill PB reports_week 3_ July 23-29_July 2018

Most of the ice was gone from the NW of Hudson Bay for the week of 23 July 2018 and the graph below shows that this is a new pattern that began in 1997, with only 2009 being an outlier:

Hudson Bay NW same week_ ice coverage 23 July 1971-2018 with trend

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Hansen’s 1988 climate change testimony was the answer to Stirling’s polar bear problem

Last week’s media coverage made me realize that James Hansen’s testimony to a US Senate committee in 1988 provided well-timed answer to a vexatious problem facing polar bear biologist Ian Stirling. Thirty years ago, Stirling was struggling to understand why polar bear productivity in Western Hudson Bay had dropped.  He was ripe for the suggestion from Hansen (and his follow-up paper) that human-caused global warming could be the explanation. An interview with Stirling and colleague Andrew Derocher published in 2016 helps connect the dots.DA-IS-measuring_Ian Stirling

Many bears were in poor condition in the fall of 1983 (Calvert et al. 1986:19, 24; Ramsay and Stirling 1988). In general, the 1980s saw weights of bears decline and cub mortality increase, with a marked increase in the loss of whole litters over what had been documented in the 1960s and 1970s (Derocher and Stirling 1992, 1995).

Until Hansen and climate change came along,  density-dependent effects (such as the number of bears out-pacing food supply) were seen as the most likely explanation. But sea ice decline blamed on human-caused global warming was suddenly a new possibility that Stirling soon embraced (Stirling and Derocher 1993). By the late 1990s, sea ice coverage on Hudson Bay had indeed declined but the correlation with polar bear productivity produced a weak trend that was not statistically significant (Stirling et al. 1999).

The 1999 Stirling paper did not provide scientific evidence to explain the 1980s decline in productivity as much as it presented a novel scapegoat to blame when a more plausible explanation could not be made.

Bottom line: Global warming could not have been the proximate cause of the productivity changes in WH polar bears documented during the 1980s but Stirling spent the next two and a half decades vigorously pushing climate change as the cause of all polar bear ills. Continue reading

Svalbard polar bear data 2016 through 2018 shows no impact of low ice years

Last week, the Norwegian Polar Institute updated their online data collected for the Svalbard area to include 2017 and 2018 — fall sea ice data and spring polar bear data. Older data for comparison go back to 1993 for polar bears and 1979 for sea ice, showing little to no impact of the reduced ice present since 2016 in late spring through fall.

Svalbard polar bear_NP015991-isbjorn-JA

Here’s what the introduction says, in part [my bold]:

“…The polar bear habitat is changing rapidly, and the Polar Basin could be ice-free in summer within a few years. Gaining access to preferred denning areas and their favourite prey, ringed seals, depends on good sea ice conditions at the right time and place. The population probably increased considerably during the years after hunting was banned in 1973, and new knowledge indicates that the population hasn’t been reduced the last 10-15 years, in spite of a large reduction in available sea ice in the same period.”

See Aars et al. 2017 for details on the 2015 Svalbard polar bear population count, keeping in mind that the subpopulation region is called “Barents Sea” for a reason: only a few hundred individuals currently stick close to Svalbard year round while most Barents Sea bears inhabit the pack ice around Franz Josef Land to the east (Aars et al. 2009; Crockford 2017, 2018).
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Critical evidence on W Hudson Bay polar bears still not published after 25 years

Polar bear researchers have been doing capture/recapture studies in Western Hudson Bay for decades yet most of the data claimed to be critical for assessing effects of human-caused global warming on this species have not been published. I raised this point in one of my early blog posts (27 Sept 2012) but the situation has not changed in 6 years. Here’s an update.

Derocher in the field in WH_CBC story 2016

From CBC story 14 Sept 2016.

Years ago now, in an oft-cited paper, Stirling and Derocher (2012) claimed to summarize the evidence that climate warming was negatively impacting polar bear health and survival. Several life history parameters were considered crucial, particularly body condition.

Despite almost a dozen papers (and perhaps more) on various aspects of WH polar bear health and life history studies based on capture/recapture data published since 2004  (e.g. Castro de la Guardia 2017; Lunn et al. 2016; Pilfold et al. 2017), none have reported the body condition data that supposedly support the claim that sea ice loss is having a severe impact — and the same is true for litter size, proportion of independent yearlings, and cub survival.1

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Problem polar bears of Churchill: first report of the season similar to 2016

The first activity report of the Churchill Polar Bear Alert Program has been released for 2017. It comes on the same week as last year’s (so about the same dates for first bears ashore both years), and reports pretty much the same activity.

Churchill PB reports_week 1_ July 10-16_July 2017

Odd that this year’s report contains no mention whatsoever of the condition of the bears as did last year’s (see below), which may have brought criticism for spoiling the media ‘message’ that WHB bears are suffering because of reduced sea ice. Better no comment at all than good news, eh?

Sea ice for the week of 10 July off Western Hudson Bay this year consisted of a broad strip of thick first year ice (>1.2m thick) just off shore.

Hudson Bay weekly ice stage of development 2017 July 10

The ice charted above looked like this on a standard ice map:

Sea ice Canada 2017 July 11

There are no other reports that I could find of polar bears ashore along the coast of Western Hudson Bay, so these bears must be the first wave.

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Much more sea ice in NW Hudson Bay this year than 2016 or 2015 at 27 May

In recent years, sea ice loss over Hudson Bay has begun with open water in the NW corner (which is just as likely due to prevailing offshore winds as ice melt) rather than along the east coast but this year that patch of ice is smaller than its been for the last two years. In addition, despite two patches of open water at either end of the Beaufort Sea, most of the coast of Alaska is still covered in thick ice — much more than existed last year, yet masses of polar bears did not die as far as I know (actually, WHB bears came ashore in excellent condition last year).

Sea ice Canada 2017 May 27

Compare to previous years:

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Polar bear mating season winds down with lots of sea ice habitat available

Habitat for polar bears is abundant worldwide as the prime feeding season passes its peak and mating season for sexually mature bears winds down.

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Battle among polar bear males for the right to mate, from this 2011 DailyMail story here.

There is much more ice than usual around Svalbard in the Barents Sea and off Newfoundland and southern Labrador, home to ‘Davis Strait’ bears. There have been no media reports of polar bears onshore anywhere (since the third week of April in Newfoundland and late January in Svalbard).

Sea ice map below for 12 May 2017:

Svalbard ice extent 2017 May 12_NIS

Compare the extent and concentration of ice around Svalbard above (at 12 May 2017) to conditions that prevailed on the same date in 2015 (below), considered a “good ice” year for local polar bears (and the year of the last population size count which registered an increase over the 2004 count):

Svalbard ice extent 2015 May 12_NIS

There hasn’t been this much ice in the area at this point in the season for many years, especially to the north of Svalbard, and levels since late April have been above even the long-term average (disregard the huge downward blip, which is clearly a sensor malfunction of some kind):

Svalbard ice extent 2017 May 12 graph_NIS

In fact, ice is pretty solid throughout the Barents Sea and East Greenland at this time:

Barents Sea ice extent 2017 May 12_NIS

Across the Atlantic, the situation is similar, with unseasonably heavy sea ice off eastern North America and the Southern Beaufort Sea.

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