Category Archives: Population

Polar bear population now 22,600-32,000 – when tallied by nation

Posted on January 8, 2013 | Comments Off on Polar bear population now 22,600-32,000 – when tallied by nation

UPDATE FEBRUARY 19, 2014 – The misleading “State of the Polar Bear” graphic is now GONE (as of January 31, 2014). A new 2013 status table is offered by the PBSG here. It has detailed text explanations and harvest information, with references, hyperlinked to each subpopulation entry (“Press the subpopulation hyperlink and more information will appear“) and may have replaced the “State of the Polar Bear” graphic that the PBSG commissioned for upwards of US$50,000, although the PBSG website says it is being “updated” [A pdf copy of the 2013 colour table is here, and my commentary on it is here.] I have left the original post as is, below.

This afternoon I came across some startling information. [updated here, here from Feb. 10, 2013, and here from April 1, 2013]

According to a dynamic summary report on the home page of the IUCN/SSC Polar Bear Specialist Group website  called State of the Polar Bear, there are now 22,600-32,000 polar bears worldwide, when tallied by nation.

Here are the numbers, by nation, listed in the State of the Polar Bear summary report (see map below):
Canada                              13,300-17,500
USA                                   1,200-1,800
Russia                               2,700-4,800
Norway                             1,900-3,600
Greenland
(Denmark)                        3,5000-4,400
Total                            22,600-32,000

The “Nations” page of the Polar Bear Specialist Group’s “State of the Polar Bear,” a dynamic summary that can be launched from the home page of the IUCN PBSG http://pbsg.npolar.no/en/dynamic/app/ [published Oct. 15, 2012] Click to enlarge.

The “Nations” page of the Polar Bear Specialist Group’s “State of the Polar Bear,” a dynamic summary that can be launched from the home page of the IUCN PBSG website, http://pbsg.npolar.no/en/ [published Oct. 15, 2012] Click to enlarge.

This is a big change from the 20,000-25,000 that has been touted as the global polar bear population since 2005 (see Aars et al. 2006; Obbard et al. 2010) and my post on polar bear population estimates.
[updated Jan. 9 2013 at 8:20 PST, see end of post]

UPDATE Jan. 7. 2014 – The PBSG has announced that a new population assessment is due later this month, see this January 1 post. The graphic described in this post has moved to the page called “Population information” and the official estimate of 20,000-25,000 is no longer present. There was no press release associated with this announcement.
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Did the PBSG game the polar bear listing process?

Posted on December 26, 2012 | Comments Off on Did the PBSG game the polar bear listing process?

I was in the process of writing about something else last week when I came across a tidbit of information that, on closer examination, turned out to be part of a much bigger issue that I thought should be documented.

The story involves some machinations behind the scenes of the international Polar Bear Specialist Group, the “PBSG,” that you might find rather astonishing – and which may have implications for the various on-going battles about the polar bear’s conservation status.

A lone polar bear walking on ice [Kathy Crane (NOAA) photo]. We'll call this a metaphor for the expulsion of Mitch Taylor from the PBSG after the Group switched from emphasizing unregulated over-hunting as the primary threat to polar bear conservation to global warming.

A lone polar bear walking on ice [Kathy Crane (NOAA) photo].
We’ll call this a metaphor for the expulsion of Mitch Taylor from the PBSG,
after the Group switched from emphasizing unregulated over-hunting
as the primary threat to polar bears to global warming.

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‘Species-threatening’ population declines vs. polar bear declines

Posted on December 16, 2012 | Comments Off on ‘Species-threatening’ population declines vs. polar bear declines

In 2008, polar bears in the United States were declared ‘threatened’ under the Endangered Species Act (USFWS 2008). The IUCN (to which the Polar Bear Specialist Group (PBSG) belongs) lists the polar bear as “vulnerable” (IUCN Red List 2012). In Canada (where 60% of the world’s polar bears reside), the polar bear is listed as a ‘species of special concern’ (COSEWIC 2008:iii).

As Jonathan Adler pointed out in an excellent article that appeared on the heels of the American ESA listing decision (Adler 2008:112), “Insofar as the listing is based upon climate models, ice-melt projections, and assumptions about the effects of habitat loss on the bear’s prospects for survival in the wild, its scientific basis is quite speculative.” These are also, as I understand it, unprecedented criteria for ESA listing – no other species has been listed as endangered or threatened based on such speculation of future conditions.

So what do actual polar bear population declines look like?

The Western Hudson Bay, Canada (WHB) subpopulation is the only one that has recently declined by a statistically-significant amount. [see previous post here on the status numbers] The WHB polar bear subpopulation makes up 3-5% of the global total for the species, currently estimated at 20,000-25,000 animals.

In this post, I’ll compare the documented WHB population decline to the declines seen in a few truly endangered animals, just to put the much-bandied about numbers into some perspective. Continue reading

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Polar bears are distributed throughout their available habitat

Posted on November 28, 2012 | Comments Off on Polar bears are distributed throughout their available habitat

All Arctic sea ice habitats that are currently suitable for polar bears have polar bears living in them 1 – even the southern-most regions of Hudson Bay that are well below the Arctic Circle (see previous post on polar bear numbers here).

Have a look at the maps below and see how well the current maximum extent of sea ice correlates with the present range of polar bears around the Arctic.

Fig. 1. Sea ice extent at April 25, 2012, from NSIDC (the winter maximum). Note that although there is sea ice in the Sea of Okhotsk (top right of the map), polar bears do not currently live there nor is there any evidence they ever did1.
Compare to the polar bear’s official range below.

Fig. 2. The global range of the polar bear, showing the 19 regional subpopulations. Map from Polar Bear Specialist Group (PBSG), with a few extra labels added.

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Population size estimates for grizzly bears in British Columbia, Canada

Posted on October 22, 2012 | Comments Off on Population size estimates for grizzly bears in British Columbia, Canada

This is a follow-up to my last post, which summarized IUCN/SSC Polar Bear Specialist Group (PBSG) polar bear population estimates and status reports, here.

I was interested to see how the PBSG population estimates compared to similar studies in other animals, so I took a look at the official 2012 population estimate for grizzly bears in British Columbia, Canada here. A couple of brief excerpts are provided below.

British Columbia is the western-most province of Canada (Fig. 1). It is roughly half the size of Greenland, while sea ice habitat of polar bears is roughly 6-7x the area of Greenland.

Just nine pages long, this grizzly bear population report is short, clear and unambiguous. While it may perhaps not explain its methods in enough detail for some folks (and it is, admittedly, a small portion of global grizzly bear territory), the report is nevertheless clear about the variations in quality of population estimates over time (which began in the 1970s and so are similar to what we have for polar bears). The report is also clear about how these historical estimates impact the current population status and trend. See Fig. 2 and 3 below for short excerpts.

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PBSG polar bear population assessment made simple

Posted on October 21, 2012 | Comments Off on PBSG polar bear population assessment made simple

[Update: Feb. 10 2013. I have corrected an oversight in the summary tables – the originals neglected to indicate that the Barents Sea subpopulation is shared between Norway and Russia (not controlled by Norway alone). Here is revised Table 1 and revised Table 2. ]

[Update 2: Sept. 26, 2013. See “Global population of polar bears has increased by 2,650-5,700 since 2001″ for further insight. I have also made slight corrections to the tables below, now marked Version 3.]

A couple of weeks ago, a news report appeared highlighting an interview with Russian biologist Nikita Ovsyannikov, deputy director of Russia’s polar bear reserve on Wrangel Island in the Chukchi Sea. This is what the news report said:

“He [Ovsyannikov] guessed the number of bears around the Chukchi Sea, which also sometimes migrate in small numbers to western Alaska, had dropped over the past three decades from “about 4,000 to no more than 1,700 at best.”

See Kelsey’s comments over at Polar Bear Alley and the comment I left there, here and my related previous post here

This media focus on Chukchi Sea polar bear numbers caught my attention because I had recently spent some time going through the 15 Polar Bear Specialist Group (PBSG) meeting reports in an effort to summarize the population estimates they provided. This international group first met in Fairbanks, Alaska in 1965 to advance and coordinate polar bear research and conservation under the auspices of the International Union for Conservation of Nature (IUCN) and the Species Survival Commission (SSC). I knew that according to the PBSG, the population of the Chukchi Sea is zero – that is, no Chukchi bears are included in the official total of 20,000-25,000 bears because no reliable survey had ever been done. Ovsyannikov’s statement to the press encouraged me to finish my summary of the population estimates in the PBSG meeting report tables.

This was not an easy task, in part due to the virtually constant changes in presentation style and format in the tables used to present the data (which appeared first in the 1981 report). For example, even between the 14th (2005) and 15th (2009) meeting reports, the population data table presents the subpopulations in different order and swaps the position of two critical columns (“status” and “observed or predicted trend”), making it extremely difficult for readers to do a quick comparison between years.

So I simplified the 2009 table (the most recent available), leaving out the future predictions as irrelevant to questions about current status. I included some population estimates and status assessments from previous reports to show the changes over time (where available). The full summary table, designated Table 1,  is provided here as a pdf. [update 2013 – this is Version 3]. However, in this format, it still spans two pages, so I composed another  table that contains the 2009 status information only (2009 is the most recent available), see Table 2, version 3 below. Viewing the data this way may surprise you.

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Good news study on Chukchi polar bears is unpublished

Posted on October 10, 2012 | Comments Off on Good news study on Chukchi polar bears is unpublished

This article from yesterday (Oct 09, 2012) caught my eye: “How many polar bears live in the Arctic?” by Jill Burke

Buried deep within this article (page 3, in the default format) is this statement by US Fish & Wildlife polar bear biologist Eric Regehr:

“In 2009, when the PBSG [Polar Bear Specialist Group] issued its population status reports, it listed the Chukchi Sea population, which Alaska shares with Russia, as being of unknown size, but one thought to be in decline because of anecdotal reports about possible over-harvesting in Russia. But now, newer research yet to be published has scientists reconsidering the status designations of the Chukchi population, Regehr said. It appears the bears in this area are reproducing well and maintaining good body condition.“

[Indeed, the latest PBSG report (Obbard et al. 2010:63) lists the Chukchi subpopulation status as “reduced” and current trend as “declining” even though the population size is “unknown.” It also states that “The trend is believed to be declining and the status relative to historical levels is believed to be reduced based on legal/illegal harvest levels that were thought to be unsustainable. Sea ice loss is one of the highest levels in the Arctic.”]

So, it turns out that what these expert polar bear biologists “believed” to be the case – without any data to back it up – is not actually true. Even with “sea ice loss [at] one of the highest levels in the Arctic,” polar bears are doing just fine. Sort of makes you wonder what else polar bear experts “believe” to be true but actually isn’t.

However, what really popped out at me was the tossed-off comment that the results of this potentially game-changing study for US polar bears (since the Chukchi subpopulations is shared between the US and Russia) have not yet been published. Nor are we told who did the study or when, even though it is complete enough for Regehr to be discussing the results with a journalist.

Finally, some good news to report, but no peer-reviewed study to quote or examine.

Again, results are in but we are not allowed to see the data. Sound familiar? See my earlier post on the critical evidence for western Hudson Bay polar bears that is also unpublished.

Really makes me wonder how many polar bears live in the Chukchi Sea? Sounds to me like they still don’t have an estimate but I suspect when they get one, we might be surprised by how big it is.

Reference
Obbard, M.E., Theimann, G.W., Peacock, E. and DeBryn, T.D. (eds.) 2010. Polar Bears: Proceedings of the 15th meeting of the Polar Bear Specialists Group IUCN/SSC, 29 June-3 July, 2009, Copenhagen, Denmark. Gland, Switzerland and Cambridge UK, IUCN.

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Western Hudson Bay polar bears are not like the others – Part 2

Posted on October 5, 2012 | Comments Off on Western Hudson Bay polar bears are not like the others – Part 2

In Part 1 of the Western Hudson Bay (WHB) polar bear story, I promised to explore the idea that rather than declining due to the effects of global warming, WHB polar bear populations may simply be returning to ‘normal’ after the rapid population increase that followed the intense over-harvests that occurred between 1890 and 1930 and again from 1945 to 1970.

Derocher and Stirling (1995:1664) had this to say about the life history features (like incidence of triplets and age of weaning) that made the polar bears of WHB unique:

“The results of our analyses suggest that the unique reproductive characteristics of polar bears in western Hudson Bay in the 1960s and 1970s were either a function of a population increasing from a depleted state and feeding on a relatively abundant prey base, or density-independent fluctuations in prey population size, or availability due to sea ice variation.“

In my last post, I discussed some of the evidence for how polar bear reproductive characteristics had changed since 1985. But how different were WHB polar bears, before and after 1985, from the other populations that had been dramatically reduced between 1890 and 1970, such as those in Svalbard/Barents Sea and Davis Strait?

There are two factors to consider in this recovery from over-harvest: population size changes and reproductive characteristics. Turns out, we don’t know much about the Davis Strait subpopulation but we do know a bit about Svalbard/Barents Sea bears since the 70s. And the Svalbard/Barents Sea vs. WHB comparison is a bit of an eye-opener.
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Critical evidence on polar bears in W. Hudson Bay is unpublished

Posted on September 27, 2012 | Comments Off on Critical evidence on polar bears in W. Hudson Bay is unpublished

In my last post, Western Hudson Bay polar bears are not like the others – Part 1 I stopped at the point where the following question arose: “The documented decline in cub survival and condition of females documented above occurred between 1985 and 1992 – what about now?”

I promised to address that question in a separate post because it revealed some interesting issues that deserve star billing.

What I found might surprise you: apparently, virtually all of the data supporting a decline in the western Hudson Bay polar bear population since 1985 has been collected but has not been published. This revelation came from none other than the 2012 summary by Ian Stirling and Andrew Derocher that I’ve mentioned before here.

[updated Sept. 28, 2012 – reference added, see below]

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The slaughter of polar bears that rarely gets mentioned (ca. 1890-1930)

Posted on September 20, 2012 | Comments Off on The slaughter of polar bears that rarely gets mentioned (ca. 1890-1930)

Chock this post up as another example of mind-blowing information you sometimes find while looking for something else.

In their dendrochronology paper on trees associated with polar bear dens in western Hudson Bay, Scott and Stirling (2002:157) reference an MA thesis in Geography by James Honderich (1991), in regards to a discussion of denning frequency during the period 1850-1899, “when polar bear hides were more or less traded consistently.”

It turns out the James Honderich’s thesis is actually a summary of polar bear harvests in Canada from about 4,000 years ago to 1935. The number of polar bears taken by Arctic explorers (1594 to mid-1900s), Hudson’s Bay Company fur traders (from 1670 to 1935) and Arctic whalers (1820s-1935) were calculated from a variety of historical sources. This post is a summary of the results for the period 1800-1935. It is likely you have never seen this astonishing information before and the implications for polar bear biology are substantial. Continue reading →

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