Category Archives: Population

Southern Beaufort polar bear ‘decline’ & reduced cub survival touted in 2008 was invalid, PBSG now admits

It is now clear that the phenomenon of bears moving across Southern Beaufort Seapbsg logo subpopulation boundaries compromised the US decision to list polar bears as ‘threatened’ and the IUCN Polar Bear Specialist Group (PBSG) knows that was the case.

As I pointed out last week, the PBSG has admitted in their 2013 status table update (pdf here) that bears move around so much between the Chukchi Sea (CS), the Southern Beaufort (SB), and the Northern Beaufort (NB) subpopulations that major changes in the boundaries of the SB subpopulation are necessary (see Fig. 1 below).

Figure 1. From the paper by Amstrup and colleagues (2005) describing the effect that movement of bears across subpopulation boundaries has on setting harvest quotas – and population estimates. Southern Beaufort boundary is solid red, Chukchi Sea is dashed yellow and Northern Beaufort is dotted light blue. “Point Barrow” is Barrow, AK (well inside the SB boundary). Click to enlarge.

Figure 1. From the paper by Amstrup and colleagues (2005) describing the effect that movement of bears across subpopulation boundaries has on setting harvest quotas and population estimates. Southern Beaufort (SB) boundary is solid red, Chukchi Sea (CS) is dashed yellow and Northern Beaufort (NB) is dotted light blue. “Point Barrow” is Barrow, AK (well inside the SB boundary). Click to enlarge.

Well, that’s not really news — changes to the SB boundaries were promised by the PBSG back in 2009 (Obbard et al. 2010), based on research by Steven Amstrup and colleagues published in 2001 and 2005. But now, in an astonishing admission, the PBSG have acknowledged that the last population survey for the SB (Regehr, Amstrup and Stirling, 2006), which appeared to register a decline in population size and reduced cub survival over time, did not take known movements of bears into account as it should have done.

In other words, that 2006 study almost certainly did not indicate bears dying due to reduced summer sea ice in the SB, as biologists said at the time — and which they presented as evidence that polar bears should be listed by the ESA as ‘threatened’ — but reflected capture of bears that were never part of the SB subpopulation and so moved out of the region.

As the PBSG said about the 2006 estimate:

“…it is important to note that there is the potential for un-modeled spatial heterogeneity in mark-recapture sampling that could bias survival and abundance estimates.” [my emphasis]

Spatial heterogeneity” means that the sampled bears could have come from more than one population, a possibility which violates a critical requirement of the statistics used to generate the population and survival estimates. “Un-modeled” means that the ‘movement of bears’ problem was not factored into the mathematical models that generated the 2006 population size and survival estimates as it should have been.

Ecologist Jim Steele pointed some of this out in his book and his guest post last year, so it’s not news that this was done.

What’s shocking is that the PBSG have now admitted that the ‘movement of bears’ issue essentially invalidates the 2006 population estimate and the much-touted ‘reduced survival of cubs.’ The reduced survival of cubs data from that SB study was a critical component of the argument that US bears were already being negatively impacted by global warming and thus, should be listed as ‘threatened’ under the ESA (US Fish & Wildlife Service 2008).

Since the population decline and reduced survival is now acknowledged to be unfounded — and perhaps deliberately so — I ask you this: will a new SB survey — soon to be released by the same lead author (Eric Regehr) — undo the broken trust in US and PBSG polar bear biologists? Continue reading

Polar bear status changes in 2013 deconstructed, with a map to the good news

You can’t figure out what’s going on with status updates from the IUCN Polar Bear Specialist Group (PBSG) without deconstructing the spin and the 2013 update is no exception. Here’s my travel guide, with a map, to the good news.

Polar Bear Subpopulations 19_2013 updates_March 20 2014_sm

I’ve finally had a chance to go through all of the details provided with the 2013 PBSG status table (pdf here). It’s just about all good news, once you wade through the spin. Numbers aside, out of the 13 populations for which some kind of data exist, five populations are now classified by the PBSG as ‘stable’ (two more than 2009), one is still increasing, and three have been upgraded from ‘declining’ to ‘data deficient’ (I explain below why this is a promotion).

That leaves four that are still considered ‘declining’- two of those judgments are based primarily on concerns of overhunting, and one is based on a statistically insignificant decline that may not be valid and is being re-assessed (and really should have been upgraded to ‘data deficient’). That leaves only one population – Western Hudson Bay – where PBSG biologists tenaciously blame global warming for all changes to polar bear biology, and even then, the data supporting that conclusion is still not available.

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Guest Post: Invasive Research is Alive and Well in Canada

This is a guest post by Kelsey Eliasson, who blogs at Polarbearalley, with his thoughts on the issue of the invasive research involved in polar bear mark-recapture studies around Churchill, Manitoba — which, as you’ll see, is a far different situation than I described for Nunavut (previous posts here, here, and here on this topic. Map below to get you oriented).

Kelsey is a writer, artist and polar bear guide who has spent 14 bear seasons watching the polar bears of Churchill. For five years, he ran Churchill’s monthly newspaper published occasionally, the Hudson Bay Post. Currently, he divides his year between the Yukon, Churchill and, occasionally, Riverton, home of Manitoba’s largest moose statue.

Churchill is in the Western Hudson Bay polar bear subpopulation, governed by the Province of Manitoba, while the community of Arviat, also in 'Western Hudson Bay' is overseen by the Government of Nunavut.

Churchill lies in the Western Hudson Bay (WHB) polar bear subpopulation, governed by the Province of Manitoba, while the community of Arviat, also in the Western Hudson Bay subpopulation, is overseen by the Government of Nunavut – different governments, different rules – as Kelsey points out below.

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Invasive Research is Alive and Well in Canada, by Kelsey Eliasson

The recent post about Foxe Basin was of particular interest to me, as I have been following the growing gap between the north and science for some time now. The stance taken by the Inuit is viewed as an inspiration by the guides over here in Churchill. For many years, we have tried to voice our deep concerns over the levels of handling and drugging that our bears (the Western Hudson Bay population) are subjected to on an annual basis.

This time last year, I tried to raise the topic for discussion after Andrew Derocher announced that ‘everything was on the table’ including feeding bears. At that time, the top polar bear researchers had sat down to discuss options for saving bears – except reducing handling and research – i.e. chasing bears down by helicopter and then shooting them with tranquilizers. Continue reading

Foxe Basin aerial survey a watershed moment for polar bear research, Part 2

As I outlined earlier this week, Canadian Inuit objected so strenuously to routine mark-recapture methods used by polar bear biologists during the early days of a Foxe Basin population study in 2008 that the work was abandoned and an aerial survey done instead.

In this post, I’ll examine how the polar bear biologists involved reacted to that crisis, which they called a “control of research” issue.

In a published version of a conference paper, co-authored by two of the original investigators of the Foxe Basin mark-recapture study, Lily Peacock and Andrew Derocher (Peacock et al. 2011:374), had this to say:

Control of research is a developing source of conflict. In recent years, some permits for management-oriented research on polar bears were denied by the Government of Nunavut, local hunting and trapping organizations in the Northwest Territories, and by Makivik Corporation in Quebec. Furthermore, in a 2009 resolution, Inuit Tapiriit Kanatami opposed the capture of polar bears throughout Canada (available by request from http://www.itk.ca), even though the application of physical marks is one of the most effective methods of population estimation. Co-management is particularly difficult in Nunavut because of the large number of subpopulations (12), which makes it difficult to fund and conduct research.” [my bold]

They raised an interesting point – since the Government of Nunavut has the power to insist biologists do more than reiterate that their way of counting bears is the only acceptable way, and because the government can deny permits to projects that don’t measure up, it can lock out traditional polar bear research for virtually all of Canada (the vast majority of Canada’s 13 subpopulations are in Nunavut, see Fig. 1), especially since aboriginal organizations in the Northwest Territories and Quebec have followed Nunavut’s lead.

Figure 1. Territory covered by the Government of Nunavut (top, Wikipedia) and the 13 polar bear subpopulations in Canada (bottom, Environment Canada).

Figure 1. Territory covered by the Government of Nunavut (top, Wikipedia) and the 13 polar bear subpopulations in Canada (bottom, Environment Canada).

That means if polar bear researchers can’t find a way to make their research mesh with Inuit concerns, they’ll be out of work in Canada. Let’s take a look at their approach and see how well it worked for them — explaining in part the new prominence of aerial surveys for population assessments. Continue reading

Tranquilizing polar bears and meat tainted with drugs

This follow-up to my last post has some new information about drug residues remaining in polar bear meat after the animals have been tranquilized.

Chukchi male 1240 lbs labeled Durner 2008

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Foxe Basin aerial survey – a watershed moment for polar bear research, Part 1

While researching the population status of Foxe Basin polar bears I came across an issue that seems to have garnered relatively little attention outside the polar bear community – Inuit objections to the handling of polar bears during mark-recapture surveys and the effect of this on polar bear research in Canada.

 Figure 1. US Fish and Wildlife biologists handling a polar bear in the southern Beaufort during a fall survey, October 24, 2001. Steve Amstrup photo.


Figure 1. US Fish and Wildlife biologists handling a polar bear in the southern Beaufort during a fall survey, October 24, 2001. Steve Amstrup photo.

Foxe Basin is a large polar bear subpopulation region that encompasses the northern portion Hudson Bay into the area west of Baffin Island, see map below (courtesy IUCN Polar Bear Specialist Group).

FoxeBasin_PBSG website_Oct 2013Mark-recapture research methods routinely used by polar bear biologists became especially contentious in Foxe Basin during a population study initiated in 2007/2008, with Inuit residents voicing objections and biologists defending its practice. The following year, the mark-recapture effort was halted and an aerial survey took its place.

The aerial survey has been completed and a report on it was released in 2012 (Stapleton et al. 2012; see previous post for results) but we’ve heard very little about what happened to that mark-recapture study and why the Government of Nunavut pulled the plug on it. I plan to change that with the next couple of posts.

I’m not claiming to understand the nuances of the story because I’m only going by available documents. However, I think it’s important to shine some light on this issue since it has clearly changed the shape of polar bear research in Canada.
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2013 PBSG polar bear status table information in one document

As I pointed out on Valentine’s Day, the IUCN Polar Bear Specialist Group (PBSG) has released a revised population estimate for polar bears of 18,349 (range 13,071-24,238), based on a new status table posted February 14, 2014.

PBSG status-table-2013_Feb 14 2014_intro

In that February 14th post, I also pointed out that as for the 2005 and 2009/2010 status tables, the PBSG did not add up the columns and give the totals — you had to do that yourself, which is how I got the numbers above (last week, I made a couple of graphs that show changes over time in their status table estimates). Oddly enough, there is now no mention of an official global polar bear estimate anywhere on the PBSG website.

In addition — and the point of this post — is that to see the details of how and why the PBSG biologists arrived at the population estimates and the status assessments they present (with references), you have to click on the hyperlinked title of each separate subpopulation in the table. While they made a one-page black and white summary of the online colour table available as a pdf (linked at the bottom of the page), they did not make the assessment details from the status table available in pdf format.

So I did it myself, via copy/paste into a Word document that I converted to a searchable pdf, without editorial comment except that I included the totals given above and noted a few glaringly obvious omissions (see below). It took me all of 30 minutes.

I offer it here for more effective scrutiny, convenient reference and archival purposes — because the way it stands now, the online table could disappear tomorrow without any hard-copy evidence of the information hyperlinked within it.

UPDATE February 26, 2014 I checked the PBSG website this morning and the omissions I noted below that were present a few days ago have been fixed. I did not receive a reply to my email notification of the issue. An updated pdf is now available.

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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.
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Polar bear population now officially 13,071-24,238 says IUCN Polar Bear Specialist Group

Without fanfare of any kind (so far), the IUCN Polar Bear Specialist Group (PBSG) has just announced, via a notice posted on its website, that it has revised the population estimate for polar bears to 18,349 (range 13,071-24,238), based on a new status table posted today.

The average is down slightly from the 2009 estimate of 19,747 (which was officially stated as “20,000-25,000″), but that “decline” is an illusion.

As for the 2005 and 2009/2010 status tables, they do not add up the columns to give the totals — you have to do that yourself, which is how I got the numbers above. There is no mention of a change to the global estimate total in any of the “announcements” on their website.

As occurred in 2005 and 2009
, an overall reduction in the total was achieved primarily through removal of an estimate present on their tables since 1993 (Laptev Sea, “800-1200″). Changing this estimate to zero reduced the average total by 1,000 but does not reflect a real-world change.

In addition, four subpopulation estimates were reduced, three of them only slighty (details below) and three subpopulation estimates (Foxe Basin, Western Hudson Bay and Southern Hudson Bay) were increased to reflect recent aerial survey results. Two others were increased slightly.

A new column has been added to the status table, again without explanation, called the Trend relative to historic level (approx. 25-yr past).” Although only seven out of 19 subpopulations had anything like an accurate estimate in 1989, four are now considered to have been “not reduced” while three are considered “reduced.” Why this is considered meaningful enough to add to the table is not clear.

The PBSG say they have decided to update the status table independent of their meetings, which means that no written report or document will be made available to explain any changes — the “justifications” will only be available online.

These are the people we are supposed to trust to provide honest and accurate information about the status of polar bears worldwide. The changes in the status table provided today, which have been made without oversight of any kind, hardly inspire confidence in the information they provide. See what you think.
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Foxe Basin polar bear status – another stable population

Foxe Basin_PBSG

Figure 1. Polar bear subpopulation regions defined by the Polar Bear Specialist Group, Foxe Basin marked.

Foxe Basin is a large subpopulation region (Fig. 1), with a total area of 1.18 million square km (Vongraven and Peacock 2011). It comprises Northern Hudson Bay and western Hudson Strait, and the area between western Baffin Island and eastern Melville Peninsula, with a large island (Southampton Island) in the middle (Figs. 2 and 3).

Figure 1. Foxe Basin polar bears subpopulation region, courtesy IUCN PBSG

Figure 1. Foxe Basin polar bears subpopulation region, courtesy IUCN PBSG

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