Category Archives: Conservation Status

Polar bears move around as sea ice habitat changes – this is what resilience looks like

Oddly, it seems some people expect polar bears to sit around and suffer (or die) when local conditions deteriorate, rather than move elsewhere.

PolarBear_2008_USGS

While there are perhaps a few places where moving is not really an option over the short term, over the long term (more than one season) polar bears are free to shift to another locale if ice conditions change (either too much ice or too little).

An announcement by the WWF last week (10 April) caught my eye, as it talked about bears moving from one area to another because of changing ice conditions — as if this was surprising, extraordinary and newsworthy. That said, at least they weren’t suggesting the bears are all going to die because of declining ice, which is a huge improvement.

See what you think of this part of the press release (below), in the context of what we know about the movement of bears between regions:

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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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Davis Strait polar bear habitat higher now than in 1979 and early 1980s

The Davis Strait polar bear subpopulation is said to be ‘vulnerable’ to the supposed effects of global warming because, like Hudson Bay, Davis Strait sea ice retreats every summer, leaving polar bears on land for several months.

However, Davis Strait bears have been upgraded to ‘stable’ status, according to the latest table (2013) issued by the IUCN Polar Bear Specialist Group (see their boundary map for Davis Strait bears below). Recent development of sea ice in the region can only improve that rating.

[More background here and heremap-DavisStrait

It seems that sea ice in Davis Strait is well above normal for this time of year – a recent announcement by the Canadian Ice Service (CIS) says it’s 10% above average, higher than it’s been in 25 years (h/t S. Goddard).

The Canadian Ice Service, an arm of Environment Canada, said there is 10 per cent more ice this year compared to the 30-year average.

We probably haven’t seen a winter this bad as far as ice for the past 25 years,” said Voight, referring to both the amount and thickness of the ice.

He said the Gulf of St. Lawrence is covered and some areas are “quite severe.” [my bold]

Full story here.

Latest ice map (March 12) below from the US National Snow and Ice Data Service (NSIDC).

As I pointed out recently here, Barents Sea ice is below average this year, largely due to natural variation in the Atlantic Multidecal Oscillation (AMO), but is higher over the western Atlantic (Sea of Okhotsk ice is below average too but there are no polar bears there).

There is lots of ice around Labrador and Newfoundland, however.

Sea ice extent 2014 March 12 NSIDC

I thought I let you see exactly what CIS are talking about: what did the ice look like 25 years ago, in 1989? What about 35 years ago, in 1979, the start of the satellite record for sea ice? It might surprise you. Continue reading

Barents Sea polar bear condition varies with AMO and spring sea ice conditions

Fig. 1. NSIDC sea ice extent at March 8, 2014 (a "MASIE" product), with labels added. Click to enlarge.

Figure 1. NSIDC sea ice extent at March 8, 2014 (a “MASIE” product), with labels added. Click to enlarge.

In its end of February report, the US National Snow and Ice Data Center (NSIDC) noted that Barents Sea ice was below average for this time of year (see Fig. 1 above, and Fig. 5 below) but suggested this was primarily due to natural variation driven by the Atlantic Multidecadal Oscillation (AMO):

“The Barents Sea has experienced consistently low extents, particularly in winter, and this year has been no different. While the Barents and Kara seas normally have close to 2 million square kilometers (772,000 square miles) of ice in February, recent years have seen 500,000 square kilometers (193,000 square miles) of ice extent or lower. This year, the Kara Sea is near average, but the Barents Sea remains low (Figure 4a). Unlike other regions in the Arctic, longer records of Barents Sea ice extent exist from records of fishing, whaling, and other activities. A recent paper (Miles et al., 2013 [2014, now in print]) examined these records, along with paleoproxy data, to examine extent over the past four hundred years. They found a 60- to 90-year cycle in Barents and Greenland seas ice extent related to the Atlantic Multidecadal Oscillation (AMO); the AMO is a basin-wide cycle of sea surface temperature variability similar to the El Niño and La Niña cycles in the Pacific, but varying over much longer periods. This research shows that in addition to the warming trend in the Arctic, some sea ice regions are likely also responding to natural climate variability.” [my bold]

The paper they cite (Miles et al. 2014, discussed elsewhere in December 2013 here) described the AMO this way:

“The AMO is a coherent pattern of basin-wide sea surface temperature (SST) variations with a period of roughly 60–90 years. ..Paleoenvironmental studies suggest that the AMO has persisted through previous centuries [Gray et al., 2004] and even millennia [Knudsen et al., 2011].”

Note that Miles and colleagues were looking at ice records on or around the sea ice maximum in winter/spring.

The Polar Bear Twist: Norwegian biologists Jon Aars and Magnus Andersen, who I’ve discussed before, have pointed out that the condition of polar bear males and females around Svalbard (Fig. 2) they examined over the last 20 years varied with the AMO and sea ice levels in spring and early summer. [research results posted at the website for Environmental Monitoring of Svalbard and Jan Mayen (MOSJ), Norwegian Polar Institute].

Figure 1. The Barents Sea polar bear subpopulation, courtesy the IUCN Polar Bear Specialist Group. "Svalbard" is the largest archipelago, in the eastern portion.

Figure 2. The Barents Sea polar bear subpopulation boundaries, courtesy the IUCN Polar Bear Specialist Group. Svalbard is the largest archipelago, closest to the East Greenland Sea.

That makes a lot of sense to me, given that spring/early summer is the most critical feeding season for polar bears because it’s when fat young seals are most easily available.

It also makes sense to me that you may need a record hundreds of years long to understand the natural variability of Arctic Sea ice in its various regions. Recall that natural variation, not global warming, is now being used to explain the large variation in annual sea ice cover in the Bering Sea (home to Chukchi Sea polar bears). 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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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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Chukchi-Beaufort sea ice atlas: check out polar bear habitat 1850-2013

It’s here – as promised and right on schedule — the sea ice atlas put together by University of Alaska Fairbanks (UAF) now has ice concentration maps for Alaska going back to 1850 — and for every year up to 2013. 

Several examples are included below: August 1850 vs August 1870, and April 1850 vs. April 1920 and April 2012.

For background, see my post announcing the site preview, which was then limited to 1953-2012 data, when it became available in late January.

Sea ice atlas_1850_Aug
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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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