Tag Archives: abundance

Science, optimism, and the resilience of polar bears in an ever-changing Arctic

Optimism in conservation science — which the Smithsonian says we desperately need (Earth Optimism Summit 21-23 April 2017, apparently a huge success) — means it’s time to acknowledge and celebrate real conservation success stories. The Smithsonian folks probably won’t say it but I will — one of those successes is the recovery of polar bears.

Female with cub_Shutterstock_PolarBearScienceIt’s time to abandon the focus on prophesies of impending loss and accept that recovery of polar bears from the over-hunting of last century has continued despite a decade of low summer sea ice (Aars et al. 2017; Crockford 2017; Dyck et al. 2017; SWG 2016; York et al. 2016). Why not focus on the numerous images of fat, healthy bears rather than the anomalous starving ones?

It’s time to let go of imagined future catastrophes based on pessimistic failures of adaptation (Amstrup et al. 2007, 2008; Atwood et al. 2016; Stirling and Derocher 2012) and acknowledge that polar bears and Arctic seals, just like Pacific walrus (MacCracken et al. 2017; US Fish & Wildlife Service 2017), are resilient species with adaptive capabilities we are are only just beginning to comprehend (Crawford and Quakenbush 2013; Crawford et al. 2015; Escajeda et al. 2018; Rode et al. 2014; Stirling and Lunn 1997; Stirling et al. 1975a; Vibe 1965). Continue reading

Franz Josef Land is a sea ice refugium for most pregnant Barents Sea polar bears

Consensus polar bear expert Andrew Derocher has been busy over the last few weeks, expounding a story of doom regarding Svalbard area polar bears (e.g. here and here), ridiculing the suggestion that Franz Josef Land is viable alternate habitat for Barents Sea bears, especially pregnant females looking for a place to den and give birth. But the facts say otherwise.

Svalbard polar bear_Aars August 2015-NP058930_press release

Below are the long answers, with references and ice maps, to the questions Derocher asked in his 21 December 2017 tweet (above), a refreshing change from the ‘take my word for it, I’m the official expert’ answer one gets from him, along with derogatory slurs directed at those who don’t share his pessimism.

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Baffin Bay and Kane Basin polar bears not ‘declining’ concludes new report

The 2016 Scientific Working Group report on Baffin Bay and Kane Basin polar bears was released online without fanfare last week, confirming what local Inuit have been saying for years: contrary to the assertions of Polar Bear Specialist Group scientists, Baffin Bay and Kane Basin subpopulations have not been declining but are stable.

polar-bear-feeding_shutterstock_sm

Until recently, the Baffin Bay (BB) and Kane Basin (KB) polar bear subpopulations, that live between NW Greenland, and Baffin and Ellesmere Islands, were assessed with confidence by the IUCN Polar Bear Specialist Group (PBSG) to be declining due to suspected over-hunting (see 2016 Report, Ch. 1, pg. 4).

It turns out they were wrong.

map-baffinbay

New (2016) polar bear subpopulation estimates for BB and KB:

Baffin Bay 2,826 (95% CI = 2,059-3,593) at 2013

                  [vs. 1546 (95% CI = 690-2,402) expected 2004]

                  vs. 2,074 (95% CI = 1,553-2,595) in 1997

  Kane Basin357 (95% CI: 221 – 493) at 2013

                    vs. 164 (95% CI: 94 – 234) in 1997

[1997 figures from 2015 IUCN Red List estimates, from Supplement, pg. 8); 2004 “expected” figure for Baffin Bay from 2016 SWG report, Ch. 1, pg. 4]

In 2014, Environment Canada’s assessments were ‘data deficient’ for Kane Basin and ‘likely declining’ for Baffin Bay (see map below):
ec_polarbearstatus_and-trends-lg_2010-2014-mapscanada_oct-26-2014

However, the results of this new study (conducted 2011-2013) would likely make KB in the map above dark blue (‘stable’), and BB light blue (‘likely stable’), depending on how the new information is interpreted (given differences in methodology between the 1991-1997 and 2011-2013 counts). Note that a recent paper by Jordan York, Mitch Taylor and others (York et al. 2016) suggested this outcome for Baffin Bay was likely (i.e. ‘stable’) but thought that the status of Kane Basin would remain ‘declining.’

This new information leaves only the Southern Beaufort subpopulation (SB) in a ‘likely declining’ condition, but since that decline was due to thick spring ice conditions in 2004-2006 (Crockford 2017), it does not reflect a response to recent loss of summer sea ice. The new population estimates for Baffin Bay and Kane Basin also suggests that a revision needs to be made to the 2015 IUCN Red List assessment with respect to the global population estimate because polar bears are clearly more abundant in Baffin Bay and Kane Basin than previously thought.

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If summer ice was critical for S. Beaufort polar bears, 2012 would have decimated them

Did we hear a huge hue and cry in 2013 about starving polar bears and low cub survival in the Southern Beaufort Sea? No, we did not. Despite the record-breaking low summer sea ice extent the year before (2012), and despite the fact that USGS biologists were putting collars on polar bear females there the spring of 2013 (Rode et al. 2014), we heard not a peep about a polar bear catastrophe in the Southern Beaufort. Odd, isn’t it?

Sea ice extent 2012 Southern Beaufort_PolarBearScience

Several polar bear biologists and sea ice experts were busy late last fall suggesting to the media that a decline in polar bear numbers in the Southern Beaufort was due to declines in summer sea ice, which they blamed on global warming (see quotes below and earlier discussions here, here and here). However, they made no mention of the fact that the record-breaking September ice extent in 2012 did not seem to have any noticeable effect on polar bear health or survival in 2013.

Sea ice maps from the National Snow and Ice Data Center (NSIDC) tell most of the story about what the media were, and were not, told about summer sea ice in the Southern Beaufort between 2001 and 2013.  Continue reading

Recent S. Beaufort polar bear count was a cherry-picked result – new evidence

New evidence has come to light that mark-recapture field work used to calculate a new population estimate for Southern Beaufort polar bears did not conclude in 2010 as implied in a widely-publicized paper last month but continued until 2013.

Amstrup w triplet_Prudhoe Bay 2005_USGS_sm

Steve Amstrup in S. Beaufort, 2005 (USGS photo), co-author of Rode et al. paper.

As I discussed previously, last month’s widely-hyped paper (Bromaghin et al. 2015 in press) – which reported a decline of ~40% between 2004 and 2010 (based on spring mark-recapture work) – was contradicted by fall survey counts that suggested strongly a population rebound would have been apparent if the mark-recapture work had continued another two years.

A new paper by Karyn Rode and colleagues (which includes Bromaghin and others (e.g. Amstrup) from the previous paper), summarized in a USGS press release issued on Monday and published online Tuesday, utilized comprehensive data collected during mark-recapture work carried out in spring from 1982 to 2013 in the Southern Beaufort Sea.

This new paper used the same kind of comprehensive data as Bromaghin and colleagues – from the same season, in the same region – to assess potentially negative effects of the mark-recapture research method itself, up to 2012 and beyond.

More on the Rode et al. conclusions later1 – for the moment, what is important is that the work described in the paper confirms that spring mark-recapture work on polar bears in the Southern Beaufort continued beyond 2010. Bromaghin and colleagues didn’t end their mark-recapture work prematurely — they actually left data collected in 2011 and 2012 out of their population estimate analysis when they had to have known the population had not finished rebounding from the 2004-2006 decline.
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Polar bear researchers knew S Beaufort population continued to increase up to 2012

Why did the Southern Beaufort polar bear population survey stop in 2010? It’s clear that the recently-published and widely-hyped new study stopped before the population rebound from a known decline was complete.

USFWS 2013-2014 PB News_cover_PolarBearScience

The researchers of the recently-published paper knew before starting their mark-recapture study in 2007 that the population decline had taken place. They also knew why the numbers dropped and that previous declines, caused by similar conditions, had been followed by a full recovery.

Did they really think a full recovery in population numbers was possible in only three four years, when cubs born in 2007 would not yet have been old enough to reproduce?

In fact, a US Fish and Wildlife Service (USFWS) fall survey of Southern Beaufort polar bears in 2012 found numbers were higher than they had been in a decade.
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S Beaufort polar bears largely recovered from known 2004-2006 decline, says new study

A bit more good news about polar bear populations, this time from an abundance study in the Southern Beaufort Sea. A paper released yesterday showed a 25-50% decline in population size took place between 2004 and 2006 (larger than previously calculated). However, by 2010 the population had rebounded substantially (although not to previous levels).

All the media headlines (e.g. The Guardian) have followed the press release lead and focused on the extent of the decline. However, it’s the recovery portion of the study that’s the real news, as it’s based on new data. Such a recovery is similar to one documented in the late 1970s after a significant decline occurred in 1974-1976 that was caused by thick spring ice conditions.

Polar bear with collar and tag_USGS_labeled

The title of the new paper by Jeffery Bromaghin and a string of polar bear biologists and modeling specialists (including all the big guns: Stirling, Derocher, Regehr, and Amstrup) is “Polar bear population dynamics in the southern Beaufort Sea during a period of sea ice decline.” However, the study did not find any correlation of population decline with ice conditions. They did not find any correlation with ice conditions because they did not include spring ice thickness in their models – they only considered summer ice conditions.

I find this very odd, since previous instances of this phenomenon, which have occurred every 10 years or so since the 1960s, have all been associated with thick spring ice conditions (the 1974-76 and 2004-2006 events were the worst). [Another incident may have occurred this spring (April 2014) but has not been confirmed].

Whoever wrote the press release for this paper tried hard to suggest the cause of the 2004-2006 event might have been “thin” winter ice caused by global warming that was later deformed into thick spring ice, an absurd excuse that has been tried before (discussed here). If so, what caused the 1974-1976 event?

It seems rather unscientific as well as implausible to even try to blame this recent phenomenon on global warming. However, neither the authors of the paper or the press release writers seemed to want to admit that 2-3 years of thick ice development in the Southern Beaufort could have been the cause of the population decline in 2004 (as for all of the previous events). No, that wouldn’t do, not in the age of global warming.

So, we are left with this equally absurd conclusion from the author:

The low survival may have been caused by a combination of factors that could be difficult to unravel,” said Bromaghin, “and why survival improved at the end of the study is unknown.

I’ve summarized the paper to the best of my understanding (there was a lot of model-speak to wade through), leaving out the prophesies of extinction, which in my opinion don’t add anything.

UPDATE November 19, 2014: Don’t miss my follow-up post, with some startling new information, Polar bear researchers knew S. Beaufort population continued to increase up to 2012
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