Category Archives: Population

Challenging NOAA’s “Arctic Report Card 2014” on polar bears

NOAA’s list of purported evidence for harm being caused to polar bears by Arctic warming is short and weak. It puts the gloomiest spin possible on the current well-being of an animal with all the earmarks of a healthy, well-distributed species.

Arctic report card 2014 screencap_Dec 18 2014

This year, polar bears are virtually the only species that NOAA mentions in their Arctic Report Card – they’ve put all their icon-eggs in one leaky basket [what happened to walrus??]. But polar bears are doing so well that to make an alarming case for polar bears as victims of Arctic warming, many important caveats had to be left out or misrepresented. Some details given are simply wrong.

This year’s polar bear chapter was penned by IUCN Polar Bear Specialist Group chairman Dag Vongraven (you might recall his email to me earlier this year) and a polar bear conservation activist from Polar Bears International (whose battle cry for donations is Save Our Sea Ice!”), Geoff York.

I challenge their four weak talking points one by one below.

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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. 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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W Hudson Bay polar bear mark-recapture study report 2013 – at last

I have finally secured a copy of the 2013 Western Hudson Bay mark-recapture study produced by Environment Canada.

The pertinent figure is below: as you can see, there was no declining trend in Western Hudson Bay polar bears between 2000 and 2011. Click to enlarge.

WH EC Polar Bear Demography report Lunn 26 Nov 2013 Final _Fig 8

I have relatives visiting so I don’t have time to do an in-depth summary but the report’s opening “Summary” is copied below and a pdf provided. More later when I have had time to look at it more closely. Background on the issue here.

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Public misled about W Hudson Bay bears since November 2013

Leading polar bear biologists knew by November 2013 that mark-recapture studies showed the Western Hudson Bay subpopulation had not changed appreciably since 2004 but none said so. This includes Steven Amstrup and Ian Stirling at Polar Bears International, Andrew Derocher (University of Alberta), and Nick Lunn (Canadian Wildlife Service), all of whom are (or have been) extensively involved in Western Hudson Bay polar bear research and have made recent statements to the media on this topic.

Polar_Bear_2004-11-15_Wapusk Nat Park_Wikipedia

More details have emerged about the status of Western Hudson Bay (WHB) polar bears (reported a few days ago here), reported this morning in NunatsiaqOnline, excerpts below.

The story reveals that there are two Canadian Wildlife Service (Environment Canada) reports containing population estimates of Western Hudson Bay polar bears – one produced in 2011 and another in November 2013 (reversing the 2011 conclusion) – that have not been made public.

[In contrast, Nunavut Government reports on their 2011 population estimate, based on aerial surveys, were made public in both draft and final report formats (and have since been peer-reviewed and published)]

The conclusion of the 2013 report, quoted in this mornings article, suggests that some of our most vocal polar bear specialists have been misleading the public about the status of the Western Hudson Bay population for the last year.
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Western Hudson Bay polar bear population is stable: press release

Slowly but surely, word is leaking out: the Western Hudson Bay polar bear population is stable at ~1000 bears, confirming the good news contained in maps posted on the Environment Canada website a few months ago (discussed by me here and here). Environment Canada has apparently been giving presentations in local Western Hudson Bay communities relaying their decision.

Courtesy IUCN PBSG

Courtesy IUCN PBSG

Yesterday, a press release was issued by one of the official Inuit organizations in Nunavut announcing the new official status of the Western Hudson Bay polar bear population.
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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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