Monthly Archives: January 2013

The 32,000 population estimate for polar bears is not an error due to counting overlapping territories twice

UPDATE FEBRUARY 19, 2014The 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.

[UPDATE April 1, 2013: see updates here and here ]

This is a brief follow-up to my last post.

I got an email from a reader suggesting that the high numbers for the world’s polar bear population, as given by the Polar Bear Specialist Group (PBSG) on their website in their State of the Polar Bear (SoPB) summary feature – as tallied by nation (22,600-32,000) – may simply be an error resulting from counting overlapping territories twice (i.e. where a subpopulation with one population estimate is shared by two nations, the total amount has been attributed to each nation, rather than giving each of them half of the total).

That is not the case and I’ll tell you why.

If you haven’t yet seen the last post, pop back and have a look – it’s short.

Then note the following:
1) Re: the numbers given for Russia (given as 2,700-4,800 in SoPB-by-nation). Russia has three subpopulations of polar bears: Chukchi (shared with the USA), Kara Sea and Laptev Sea. See previous post here on these estimates by the PBSG.

Chukchi officially has a population of zero because it has never been surveyed. The same is true for the Kara Sea: its population is officially zero and always has been. The Laptev Sea is given a tentative estimate of 800-1,200 in most subpopulation estimates but on the “State of the Polar Bear” summary, it is given as zero. Thus, at the very most, the total for Russia could be 800-1,200.

Conclusion: the estimate of 2,700-4,800 for the Chukchi Sea is not a result of an overlap in count. It’s a new number and there is no information given about where it comes from (it’s remotely possible that the SoPB-by-nation number comes from a recent survey of the Chukchi Sea, see previous post here, but that number has not been made public and the study results have not yet been published).

2) Re: numbers for the USA (given as 1,200-1,800 in SoPB-by-nation). The US has two subpopulations: Southern Beaufort (which it shares with Canada) and the Chukchi Sea (which it shares with Russia). The number usually given for the Southern Beaufort is 1,200-1,800 – so the US share is something like 600-900. While the US shares the Chukchi population with Russia, the Chukchi has never been surveyed – its population is officially zero (half of zero is still zero).

Conclusion: if there has been any “doubling up” going on, it is here. The official (documented) number for the US should be about 600-900.

3) Re: numbers for Greenland (given as 3,500-4,400 in SoPB-by-nation). East Greenland has never been surveyed and the official estimate for that subpopulation is zero. West Greenland comprises three polar bear subpopulations that it shares with Canada: Baffin Bay (total count 1,544-2,604), Davis Strait (total count 1,811-2,534) and Kane Basin (total count 94-234). That comes to 3,449-5,372. Conclusion: if there had been a “doubling” of shared population numbers, the number for Greenland should have been listed in the SoPB-by-nation map as 3,449-5,372 (not 3,500-4,400).

The estimate for the world’s polar bear population, as given by the Polar Bear Specialist Group (PBSG) on their website in their State of the Polar Bear summary feature – as tallied by nation (22,600-32,000) – is not simply an error resulting from counting overlapping territories twice.

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

UPDATE FEBRUARY 19, 2014The 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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Polar bears in winter: insights from Behouden Huys, 1596-1597

As a follow-up to my previous post on polar bears giving birth (December is polar bear nativity month) I thought I’d continue the generalized theme of “polar bears in winter.”

polar bear aurora_borealis_3-t2 free

While we don’t really know for sure what non-pregnant polar bears do during the depth of the Arctic winter, we have bits of evidence – some from modern hunters and polar bear researchers but also from Arctic explorers. One explorer in particular comes to mind: William Barents [Willem Barentsz] of Holland, who attempted to reach China via the Arctic Northeast Passage in the late 16th century. On their third voyage (1596-1597), Barents and his crew were forced to spend the winter on the northern tip of Novaya Zemlya (latitude 760N, see Fig. 1) when their ship became trapped in the sea ice. Crew member Gerrit De Veer (1609) kept a journal account of the long, horrifying winter they spent on shore, in a shelter they built with materials salvaged from the ship. They called their winter home Behouden Huys (“the saved house”).

Figure 1. Location of Novaya Zemlya, in the Barents Sea. On the map at left (a), the black square marks the location of Behouden Huys, the over-winter home of William Barents and his crew (1596-97) on Novaya Zemlya (the “track of boats” noted marks the return journey of Barents in the summer of 1597). This is modified from Zeeberg et al. 2002:331. The map on the right is from Wikipedia, for perspective. click to enlarge.

Figure 1. Location of Novaya Zemlya, in the Barents Sea. On the map at left (a), the black square marks the location of Behouden Huys, the over-winter home of William Barents and his crew (1596-97) on Novaya Zemlya (the “track of boats” noted marks the return journey of Barents in the summer of 1597). This is modified from Zeeberg et al. (2002:331). The map on the right is from Wikipedia, for perspective. click to enlarge.

An English translation of De Veer’s journal is now available online and it offers a fascinating glimpse of what it meant to live through that long dark winter under almost-constant fear of attack by polar bears. The Dutchmen were plagued by polar bears almost the entire time they were on Novaya Zemlya (see Fig. 2). De Veer’s notes on these encounters provide a unique perspective on polar bear activities over the Arctic winter – ironically, it is not the havoc the bears caused that provides the most important clue but rather, the timing of when they left Barents and his crew alone.

Figure 2. An engraving from De Veer’s journal conveys the struggle the crew faced in warding off polar bears during their winter stay at Novaya Zemlya. The bears not only stalked and attacked the crew - they got into the food stores on the ship (From Wikipedia).

Figure 2. An engraving from De Veer’s journal conveys the struggle the crew faced in warding off polar bears during their winter stay at Novaya Zemlya. The bears not only stalked and attacked the crew, they got into the food stores on the ship.
(From Wikipedia).

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