Tag Archives: Derocher

Barents Sea polar bear status and sea ice declines

Posted on October 15, 2013 | Comments Off on Barents Sea polar bear status and sea ice declines

So far, I’ve not discussed the Barents Sea subpopulation in very much detail, except in comparison to other groups. For example, the Barents is considered to be the same type of sea ice “ecoregion” as the Chukchi Sea and the Southern Beaufort (discussed here). Previous studies on the Barents Sea polar bear population (Derocher 2005) indicate it may have recovered from extreme levels of overhunting (discussed here) and had stabilized, or was increasing very slowly, as early as 2002 (discussed here) — similar to what has happened in Davis Strait (discussed here).

Figure 1. Polar bear subpopulations, with the Barents Sea region highlighted; map courtesy the IUCN Polar Bear Specialist Group (PBSG), extra labels added.

Figure 1. Polar bear subpopulations, with the Barents Sea region highlighted; map courtesy the IUCN Polar Bear Specialist Group (PBSG), extra labels added.

The most recent Barents Sea population estimate was done in 2004 (2,650; range ~1900-3600), based on an aerial survey (Aars et al. 2009). Aerial surveys are the only practical method of establishing population counts in regions like this where many bears never set foot on land. The previous estimate for the Barents (1982) was “2,000-5,000” but its accuracy was considered “poor” (discussed here).

The IUCN Polar Bear Specialist Group (PBSG), in their most recent report, lists the Barents Sea population as “data deficient” for status, current trend and estimated risk of decline within 10 years (Obbard et al. 2010:62, Table 1) and the “notes” for this entry say:

“Population estimate is based on a new aerial survey. There was likely an increase in the subpopulation size after 1973 until recently. Current growth trend is unknown.”

This 2004 estimate is now almost a decade old and potentially no longer an accurate representation of what’s happening in the Barents Sea. The most up-to-date information has not yet been published but it is available online. It’s eye-opening to say the least, if only that it appears to be yet another example of a polar bear population that is so far not showing signs of being harmed by sea ice declines, as I’ve discussed before (here).

[Update October 15, 2013: I’ve simplified the text discussion and figure regarding the Aars and Andersen denning study from the original posted]

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Polar bears have not been harmed by sea ice declines in summer – the evidence

Posted on August 18, 2013 | Comments Off on Polar bears have not been harmed by sea ice declines in summer – the evidence

PB logo colouredThe polar bear biologists and professional activists of the IUCN Polar Bear Specialist Group (PBSG) continue to insist that since 1979 increasingly smaller amounts of Arctic sea ice left at the end of summer (the September ice minimum) have already caused harm to polar bears. They contend that global warming due to CO2 from fossil fuels (“climate warming” in their lexicon) is the cause of this decline in summer ice.

In a recent (2012) paper published in the journal Global Change Biology (“Effects of climate warming on polar bears: a review of the evidence”), long-time Canadian PBSG  members Ian Stirling and Andrew Derocher (both of University of Alberta) summarized their position this way:

“Climate warming is causing unidirectional changes to annual patterns of sea ice distribution, structure, and freeze-up. We summarize evidence that documents how loss of sea ice, the primary habitat of polar bears (Ursus maritimus), negatively affects their long-term survival”

I’ve spent the last year examining their evidence of on-going harm, but in addition, I’ve looked at the evidence (much of it not mentioned in the Stirling and Derocher paper1) that polar bears have either not been harmed by less sea ice in summer or have thrived in spite of it.

This is a summary of my findings. I’ve provided links to my original essays on individual topics, which are fully referenced and illustrated. You are encouraged to consult them for complete details. This synopsis (pdf with links preserved, updated; pdf with links as footnotes, updated) complements and updates a previous summary, “Ten good reasons not to worry about polar bears” (pdf with links preserved; pdf with a foreword by Dr. Matt Ridley, with links as footnotes).

Update 8 September 2013: to include links to my post on the recently published Chukchi population report; updated pdfs have been added above.

Update 22 January 2014: added figure comparing March vs. September sea ice extent using the same scale, from NOAA’s “2014 Arctic Report Card,” discussed here.
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Southern Hudson Bay subpopulation status, farthest south of all polar bears

Posted on July 25, 2013 | Comments Off on Southern Hudson Bay subpopulation status, farthest south of all polar bears

“The Arctic” is a bit hard to define. While the Arctic Circle works as a good boundary for some purposes and the 100C isotherm for July for others, neither work for polar bears because several subpopulations live well south of these limits (Fig. 1).

In the east, Western Hudson Bay, Southern Hudson Bay and Davis Strait are all located well south of the Arctic Circle and the first two (and half of Davis Strait) are beyond the 100C July isotherm as well. In the western Arctic, the Chukchi Sea subpopulation is within the 100C July isotherm but at least half of its bears reside south of the Arctic Circle (Fig. 1) in the Bering Sea (see previous post here).

Unique amongst all of these is Southern Hudson Bay – all of its polar bears make maternity dens and/or spend the summer south of 600N.

Southern Hudson Bay (SH) bears live in the Canadian provinces of Ontario, while Western Hudson Bay (WH) bears reside in Manitoba and Nunavut. The two groups mix over the winter but appear to spend the summer/fall in their respective regions (Stirling et al. 2004). [See previous posts on Western Hudson Bay bears here, here, and here]

“Further south” in the Arctic usually means warmer, with open water present more weeks every summer, sea ice for fewer weeks over the winter. So, shouldn’t the bears of Southern Hudson Bay be already suffering more harm from global warming than virtually all other subpopulations, including those in Western Hudson Bay?

After all, Western Hudson Bay bears appear to have experienced a statistically significant decline in numbers, among other effects (Regehr et al. 2007; Stirling and Derocher 2012) — surely Southern Hudson Bay bears are doing worse?

You’d think so, but they aren’t.

Figure 1. Boundary limits for “the Arctic” (top map) such as the Arctic Circle (dashed line) or the 100C isotherm for July (solid red line) would not include several polar bear subpopulations that live south of these.

Figure 1. Boundary limits for “the Arctic” (top map) such as the Arctic Circle (dashed line) or the 100C isotherm for July (solid red line) would not include several polar bear subpopulations that live south of these.

UPDATED October 28, 2014: Reference added, Obbard et al. 2013 (aerial survey results).
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Chukchi polar bear status contradicts the “message” – new details

Posted on July 7, 2013 | Comments Off on Chukchi polar bear status contradicts the “message” – new details

Previously, I summarized preliminary results of polar bear research in the Chukchi Sea undertaken between 2008 and 2011 by US Fish & Wildlife biologist Eric Regehr and US Geological Survey researcher Karyn Rode. At the time, a peer-reviewed paper on this study was promised shortly.

It now appears this paper is indeed on the way. I’m sure of that because a few weeks ago, I came across a conference presentation given by Karyn Rode that is a summary of the upcoming Chukchi research paper. The title of both presentation and ‘in review’ paper is:

“Variation in the response of an Arctic top predator experiencing habitat loss: feeding and reproductive ecology of two polar bear populations.”

Rode’s slide presentation (given at the annual Lowell Wakefield Fisheries Symposium at the end of March, in Anchorage, Alaska) was posted online by the symposium organizers. It provides some very interesting details on the status of Chukchi Sea bears compared to bears in the Southern Beaufort, and contains some mighty “inconvenient” conclusions that should raise some eyebrows.

I’ve summarized these details and conclusions below in point form, below the maps.

Figure 1. Chukchi and Beaufort Seas (from Wikipedia), upper. ‘Chukchi Sea’ polar bears are shared between the USA and Russia; ‘Southern Beaufort’ bears are shared between the US and Canada, lower (from PBSG, with labels added). Pink dots are the subpopulations featured in the Rode et al. presentation and upcoming paper.

Figure 1. Chukchi and Beaufort Seas (from Wikipedia), upper. ‘Chukchi Sea’ polar bears are shared between the USA and Russia; ‘Southern Beaufort’ bears are shared between the US and Canada, lower (from PBSG, with labels added). Pink dots are the subpopulations featured in the Rode et al. presentation and upcoming paper.

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Great polar bear red herring in the Southern Beaufort

Posted on July 4, 2013 | Comments Off on Great polar bear red herring in the Southern Beaufort

Red herring iconWe know that thick-ice springs occurred in 1974, 1975, 1986, 1992, 2004, and 2005 in the former ‘Eastern Beaufort’ – now the southern portion of the ‘Northern Beaufort’ and the eastern portion of the ‘Southern Beaufort.’ We know that these severe spring ice conditions negatively impacted both polar bears and ringed seals in this region every decade since the 1960s because the effects have been documented by numerous studies conducted in April through May for polar bears (Amstrup et al. 2006; Cherry et al. 2009; Pilfold et al. 2012; Stirling 2002; Stirling and Lunn 1997; Stirling et al. 1980; Stirling et al. 1993; Stirling et al. 2008) and in June and July for ringed seals (Harwood et al. 2012; Smith 1987), see previous posts here, here, and here.

For example, even though Ian Stirling and colleagues argued in their 2008 paper that the thick spring ice conditions in 2004, 2005 and 2006 (but not those in previous decades) were caused by storms initiated or intensified by greater amounts of open water in previous summers, they did not deny that the thick-ice springs occurred. They stated quite clearly that:

“The 1960s, 1970s, and 1980s each experienced a two- to three-year decline in seal productivity in the eastern Beaufort Sea and Amundsen Gulf, associated with heavy ice conditions, around mid-decade. Each was followed by a decline in polar bear reproduction and condition, after which both seal and bear populations recovered (Smith, 1987; Harwood et al., 2000; Stirling, 2002). The beginning of each of those three periods was associated with heavy ice conditions through the winter before the reproductive decline of the seals, followed by a late spring breakup.” [my bold]

So, I have to say, I was shocked but not surprised to find that in the more recent scientific literature, the phenomenon of thick-ice springs every decade in Southern and Northern Beaufort has been deliberately ‘disappeared.’ 

Not surprised because I suspected it had happened — this issue was a feature of the Stirling and Derocher (2012) paper from late last year which was the topic of my very first blog post, “Cooling the polar bear spin.”

However, I think it is important to document how the transmogrification of sea ice effects on polar bears was managed in the scientific literature so that everyone can see exactly what has been done. In a truly astonishing move for what is supposed to be a field of science, thick-ice springs have been effectively replaced by an open-water red herring as the scourge of Southern Beaufort polar bears.

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Guest post: How ‘science’ counts bears

Posted on July 3, 2013 | Comments Off on Guest post: How ‘science’ counts bears

This essay by Dr. Jim Steele, professor emeritus, San Francisco State University, is reblogged from a July 3 2013 post at WUWT post, with Dr. Steele’s permission. I am not a field biologist and have never done a mark-recapture study but Dr. Steele has. His perspective on the way polar bear biologists count bears and estimate survival in the Southern Beaufort is a perfect companion to yesterday’s post, a related post that I’ll put up later this week, and this one from December, among others. I’ve added links to the references cited in this essay where they are available, as is my custom. See the original post for Jim’s responses to comments and questions.

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Guest post by Jim Steele   “How ‘science’ counts bears”

The Inuit claim “it is the time of the most polar bears.” By synthesizing their community’s observations they have demonstrated a greater accuracy counting Bowhead whales and polar bears than the models of credentialed scientists. To estimate correctly, it takes a village. In contrast the “mark and recapture” study, which claimed the polar bears along South Beaufort Sea were victims of catastrophic global warming and threatened with extinction, relied on the subjective decisions of a handful of modelers.

In mark and recapture studies, the estimate of population abundance is skewed by the estimate of survival. For example, acknowledging the great uncertainty in his calculations of survival, in his earlier studies polar beat expert Steven Amstrup reported three different population estimates for bears along the South Beaufort Sea. If he assumed the adult bears had an 82% chance of surviving into the next year, the models calculated there were 1301 bears. If survivorship was 88%, the abundance climbed to 1776 bears. If he estimated survivorship at a more robust 94%, then polar bear abundance climbed to 2490.1 Thus depending on estimated survival rates, a mark-and-recapture study may conclude that the population has doubled, or that it has suddenly crashed.

Here are the simplified basics of estimating survival.

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Signs that Davis Strait polar bears are at carrying capacity

Posted on June 10, 2013 | Comments Off on Signs that Davis Strait polar bears are at carrying capacity

Exciting news about polar bears in eastern Canada: the peer-reviewed paper on the Davis Strait subpopulation study has finally been published (Peacock et al. 2013). It concludes that despite sea ice having declined since the 1970s, polar bear numbers in Davis Strait have not only increased to a greater density (bears per 1,000 km2) than other seasonal-ice subpopulations (like Western Hudson Bay), but it may now have reached its ‘carrying capacity.’

This is great news. But where is the shouting from the roof-tops? This peer-reviewed paper (with its juicy details of method and analysis results), considered by some to be the only legitimate format for communicating science, was published February 19, 2013. No press release was issued that I could find and consequently, there was no news coverage. Funny, that.

There was a bit of shouting back in 2007 when the study ended and the preliminary population count was released – polar bear biologist Mitch Taylor is quoted in the Telegraph (March 9 2007) as saying:

“There aren’t just a few more bears. There are a hell of a lot more bears.”

There was also a CBC news item in January 2007 and a Nunatsiaq|Online report in October 2009 when the official government report was completed. But these were all based on preliminary information and focused on the population increase only.

This new paper (Peacock et al. 2013) reveals that the story in Davis Strait is about more than simple population growth. Small wonder no one is drawing attention to it. Continue reading

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Cannibalism update and insight on the timing of media hype

Posted on April 19, 2013 | Comments Off on Cannibalism update and insight on the timing of media hype

In my last post, I went over some of the spin and misrepresentation of fact contained in the claim by leading polar bear biologists Steven Amstrup, Ian Stirling and Andrew Derocher (Amstrup et al. 2006; Stirling and Derocher 2012) that cannibalism is on the increase because of the effects of global warming on Arctic sea ice.

I’ve had an opportunity to follow up on three points that puzzled me. Three relate to the Amstrup et al. paper that described three cases of cannibalism in the southeastern Beaufort Sea in 2004 and one to the incidents in western Hudson Bay in 2009. In the process, I found at least three more misrepresentations of fact and gained some insight on why these incidents of cannibalism were hyped so enthusiastically when they were. Continue reading

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Cannibalism in polar bears: spin and misrepresentation of fact galore

Posted on April 10, 2013 | Comments Off on Cannibalism in polar bears: spin and misrepresentation of fact galore

In my next to last post, I discussed some of the anecdotal reports of den collapses included in the peer-reviewed summary of facts presented by biologists Ian Stirling and Andrew Derocher (2012) that supposedly support the premise that global warming is already having an impact on polar bear populations (discussed previously here, here, and here), prophesied to be even greater in the future. While they admit that such reports are not based on scientific studies, they nevertheless include them in their published list of global warming impacts, and not surprisingly, that is how others have interpreted them.

The same is true for their treatment of the phenomenon of cannibalism in polar bears. In that same paper, Stirling and Derocher (2012:2701) have a section called “Anecdotal observations consistent with predictions of the effects of climate warming.” This section begins with a discussion of cannibalism:

“There have been several well-publicized observations that are consistent with predictions of the effects of climate warming on polar bears, but cannot be statistically linked. For example, intraspecific aggression and cannibalism were predicted to increase in polar bears with climate warming (Derocher et al. 2004, Table 1). Observations of infanticide and cannibalism by thin adult males on land during the open water period have been documented (e.g., Lunn & Stenhouse, 1985; Derocher & Wiig, 1999; Amstrup et al., 2006; Stone & Derocher 2007). Such events have been known to occur for many years and, although their significance is unclear, there is some evidence suggesting the frequency of occurrence is increasing in areas where bears fast on land for extended periods. ” [my bold]

And this is the evidence for the supposed increase in occurrence:

“For example, in late summer and autumn 2010 [sic], there were eight observations of cannibalism on the western coast of Hudson Bay compared to one or two in the previous 5 years (I. Stirling, unpublished data).” [my bold; 2010 should be 2009 – more on this later.]

Were these observations of cannibalism made by polar bear researchers or someone else? Were there as many observers in the area in each of the five years prior to the year they occurred, as there were when these incidents were observed? We don’t know, because it’s unpublished data.

Stirling and Derocher have again included critical information in their list of facts that has not been published. I guess I’ll have to add “evidence for cannibalism” to my previous list of “Critical evidence on polar bears in W. Hudson Bay is unpublished” (see also “Stirling and Derocher’s sea ice trick”) [there is more information available, but it’s not from peer-reviewed sources – more on this below]

In this post, I take a look at some of the evidence that is published, some of the media interviews and reports that followed, and the information that came from a press release issued by an advocate group. I’ve made a table summarizing the details of all recent papers and reported incidents, and some of them are described in more detail. In a footnote, I have a brief summary of why polar bears kill and eat each other.

These details reveal some rather shocking evidence of scientists misrepresenting evidence – in their peer-reviewed papers and in interviews with the media – and bathing their global warming prophesies in the blood-lust of cannibalism. It’s past time to shine a big bright light on the cannibal issue, so pardon the length of this post.

[See followup post April 19 here]

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Collapse of polar bear snow dens – Stirling and Derocher’s anecdotal evidence

Posted on April 5, 2013 | Comments Off on Collapse of polar bear snow dens – Stirling and Derocher’s anecdotal evidence

In their summary of facts supposedly supporting the premise that global warming is already having an impact on polar bear populations (discussed previously here, here, and here), biologists Ian Stirling and Andrew Derocher (2012:2700) include a list of incidents of warm winter weather and/or “rain on snow events” that have led to the collapse of polar bear maternity dens and ringed seal birthing lairs.

Stirling and Derocher state that both polar bears and ringed seals (their primary prey) have a demonstrated

“high vulnerability …to increased mortatily resulting from warm temperatures and rain. Such rain on snow events are predicted to increase as the climate warms in the Arctic (Hansen et al. 2011).”[my bold]

However, their so-called evidence for polar bears and ringed seals having a proven vulnerability to these events comes not from scientific studies but what they admit outright are anecdotal reports.

They describe four incidents, including one case of a maternity den collapse (involving a 6 yr old, probably first-time mother and two, 3-4 week old cubs) in the southern Beaufort in 1989, apparently caused by a bit of warm weather followed by heavy snow in late January (a picture of the dead bear is included, see below, just so we don’t forget that a bear died).

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