Tag Archives: population increase

Global population size estimates for polar bears clash with extinction predictions

How many polar bears are there in the world? This was the primary question the International Union for Conservation of Nature (IUCN) had for the newly-formed Polar Bear Specialist Group (PBSG) back in 1968. Assessing the species global population size was part of the group’s mandate ahead of the 1973 international treaty to protect polar bears from wanton overhunting. For decades, this was an important objective for the scientists that made up the group.

However, about 15 years ago that goal disappeared. I contend it was abandoned because it had become incompatible with the PBSG claim that polar bears are ‘Vulnerable’ to extinction due to human-caused global warming. The group now insists that global population estimates cannot be used to determine if numbers have gone up or down: a Catch-22 that prevents public and scientific scrutiny. This is why they push back so hard when anyone suggests that global polar bear numbers have increased.

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Sea ice off Newfoundland thickest ever yet another polar bear comes ashore

Amid reports that ice conditions between Newfoundland and southern Labrador are the worst in living memory, another polar bear was reported ashore in the area — just after biologist Andrew Derocher explained to the CBC that bears only come on land when sea ice conditions “fail.”

Strait-of-belle-isle pack ice_April 19 2017_Nordik Relais

“Ice too thick for coast guard’s heavy icebreaker” said a 20 April 2017 CBC report on the state of ice in the Strait of Belle Isle. The pack is thick first year ice (four feet thick or more in places) and embedded with icebergs of much older, thicker ice. The ice packed along the northern shore of Newfoundland is hampering fishermen from getting out to sea and is not expected to clear until mid-May.

NASA Worldview shows the extent of the pack ice over northwest Newfoundland and southern Labrador on 19 April 2017 (the Strait of Belle Isle is the bit between the two):

Newfoundland Labrador sea ice 19 April 2017 NASA Worldview

The same day that the above satellite image was taken (19 April), at the north end of the Strait on the Newfoundland side, a polar bear was spotted in a small community northwest of St. Anthony (marked below,  “Wildberry Country Lodge” at Parker’s Brook). It’s on the shore of north-facing Pistolet Bay on the Great Northern Peninsula, near the 1000 year old Viking occupation site of L’Anse aux Meadows.

Parkers Brook location on Pistolet Bay

There were no photos of the Parker’s Brook bear but lots of others have been taken this year of almost a dozen seen along Newfoundland shorelines since early March: see my recently updated post, with an updated map of reported sightings. Harp seals are now abundant in the pack ice of southern Davis Strait, providing polar bears with an ample source of food when they need it most and therefore, a strong attractant to the area.

St brendan's bear 01 VOCM report 5 April 2017 Tracy Hynes

Yet, as I reported yesterday, polar bear specialist Andrew Derocher told the CBC this week that polar bears are almost always “forced” ashore by poor ice conditions. The CBC report included his tweet from 10 April, where he suggested “failed” Newfoundland ice conditions were the cause of multiple bears onshore in Newfoundland this year.

Similar thick ice conditions off northern Newfoundland (perhaps even worse) occurred in 2007, see Twillingate in the spring of 2007 below:

Twillingate-heavy ice-20070523_2007 CBC David Boyd photo

Yet, in 2007 there was not a single polar bear reported onshore in Newfoundland (as far as I am aware) but this year there were almost a dozen. And the photos taken this year show fat, healthy bears – not animals struggling to survive.

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Polar bears roaming Labrador in winter due to climate change, says minister

This is a follow-up to a post on my book blog that I wrote this morning because it’s relevant to the scenario I describe in my novel, set in the year 2025 in northern Newfoundland. I’m cross posting it for the benefit of regular readers here.

It appears that most of the blame for this phenomenon of multiple sightings of hungry bears onshore in the dead of winter (creating havoc and roaming among houses in the coastal Labrador communities of Black Tickle and Charlottetown) has been placed squarely on…climate change. By a government minister. You have to hear this man’s words to believe it.

Labrador south and Fogo Nfld marked

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Are Polar Bears Really Endangered?

Christina Wu at the Urban Times (July 3, 2014) recently asked this question. She came up with a surprisingly balanced argument but some predictable responses from IUCN Polar Bear Specialist Group (PBSG) biologists. As a consequence, she overlooked some critical facts that make a big difference to the answer.

Figure 1. Are polar bears really endangered? The US Fish and Wildlife Service thinks so, but only because Steven Amstrup, based on a computer model projecting sea ice out to 2050, said so (Amstrup et al. 2007). This information has been used by the Center for Biological Diversity and other NGOs, like WWF and Polar Bears International (where Amstrup is now employed), to solicit donations.

Figure 1. Predictions of polar bear population declines by 2050 are being used by the Center for Biological Diversity, WWF and Polar Bears International to solicit donations.

UPDATED 18 May 2015 – see below.

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Graphing polar bear population estimates over time

I’ve already commented on the 2013 update of polar bear population status released by the IUCN Polar Bear Specialist Group (PBSG).

However, I thought it might be interesting to graph the changes in global population estimates over time (from 1981-2013) — not just the actual estimates from PBSG status tables (with their min/max error ranges) but those totals plus the so-called “inaccurate” estimates that the PBSG have dropped from their accounts in recent (2005-2013) assessments: Chukchi Sea, East Greenland, Queen Elizabeth Islands (now known as the “Arctic Basin”), and Laptev Sea.

In 2001, those “inaccurate” estimates contributed 5,000-5,400 bears to the global total, but now they’re gone — no bears from those regions contribute to the official totals listed on recent PBSG status tables.

Adding those dropped estimates back into the global totals makes it possible to generate a graph in which the global estimates are truly comparable over time.

To see how the dropped estimates influenced the perception of population change over time, I’ve also graphed the estimates given by the PBSG in their status tables. I’ve combined the two into one image (Fig. 1, click to enlarge) to make comparison easy.

UPDATE 5 December 2014: Links to more recent posts relevant to this issue added below. The most recent numbers, added 31 May 2015, are here.

UPDATE 26 March 2019: See “Latest global polar bear abundance ‘best guess’ estimate is 39,000 (26,000-58,000)
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Polar Bear Specialist Group population status update – officially postponed

I kept a close watch on the website of the IUCN Polar Bear Specialist Group (PBSG) over the weekend to see if an actual population status update might eventually appear (see my last post).

Nothing all weekend, but today (Monday, February 3), the “Population status – Status table” tab (where the 2010 status table was inserted on Friday), returned an error message — the out-of-date status table put up on the day an updated one was promised was simply gone.

However, I noticed that the last sentence of the original December 16, 2013 “Population status reviews announcement had been changed, without any indication that it had been amended.

From December 16, 2013 until February 2, 2014 that last sentence said:

“The new status table and assessments will be published as they are available in web format no later than February 1, 2014.

Now it reads:

“The new status table and assessments will be published as they are available in web format in February, 2014.” [my bold]

The date stamp on this page is February 3, 2014, see screen cap below.

What do you call this — “Bayesian transparency”? I think it means a polar bear population status update may be forthcoming…sometime.

PBSG Population status reviews_Feb 3 2014 notice

Global population of polar bears has increased by 2,650-5,700 since 2001

The official population estimates generated by the IUCN Polar Bear Specialist Group (PBSG) give the impression that the global total of polar bears has not changed appreciably since 2001:

2001 PBSG report                  21,500-25,000

2005 PBSG report                  20,000-25,000

2009 PBSG report                  20,000-25,000

2013 PBSG website                20,000-25,000

2015 IUCN Red List              22,000-31,000 [see latest update note]

However, some accounting changes were done between 2001 and 2009 (the latest report available) that mean a net increase in numbers had to have taken place (see summary map below and previous post here. Note this is a different issue than the misleading PBSG website graphic discussed here).

And while it is true that population “estimates” are just that — rather broad estimates rather than precise counts — it is also true that nowhere do the PBSG explain how these dropped figures and other adjustments were accounted for in the estimated totals. 

The simple details of these changes are laid out below, in as few words as I could manage, to help you understand how this was done and the magnitude of the effect. It’s a short read — see what you think.

UPDATE 15 May 2016: In late November 2015, the IUCN Red List of Threatened Species published a new assessment for polar bears that estimated the global population at 22,000-31,000 and stated the trend was ‘Unknown’. See details here and here – which includes links to the official report and the press release. Sorry for the delay in updating this post.

UPDATE 31 May 2015: See the latest population numbers here.

UPDATE 5 December 2014: Links to more recent posts relevant to this issue added below. [including this one: Status of Canadian polar bear populations has been changed – more good news October 28, 2014

UPDATE February 14, 2014a new status table has been released, see new post here 

UPDATE February 18, 2014 — see graphs of the 1981-2013 estimates here.

Polar bear subpopulations as defined by the PBSG: Top, in the 2001 report; Bottom, 2009 report. Map courtesy PBSG, with a few labels added and the subpopulations identified where “accounting” changes or adjustments to estimates took place.SB, Southern Beaufort; NB, Northern Beaufort; VM, Viscount Melville; MC, M’Clintock Channel; LS, Lancaster Sound; GB, Gulf of Boothia; NW, Norwegian Bay; KB, Kane Basin; WH, Western Hudson Bay. Click to enlarge.

Polar bear subpopulations as defined by the PBSG: Top, in the 2001 report; Bottom, 2009 report. Map courtesy PBSG, with a few labels added and the subpopulations identified where “accounting” changes or adjustments to estimates took place.
SB, Southern Beaufort; NB, Northern Beaufort; VM, Viscount Melville; MC, M’Clintock Channel; LS, Lancaster Sound; GB, Gulf of Boothia; NW, Norwegian Bay; KB, Kane Basin; WH, Western Hudson Bay. Click to enlarge.

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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