Monthly Archives: February 2014

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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Thriving Foxe Basin and Davis Strait polar bears threaten nesting sea birds

UPDATE February 11, 2014. A reader (Kevin, at “Afton’s Waterfowl List”) has pointed out an error in Fig. 3, where I inadvertently labeled the bars on the upper graph as ending in 2011 instead of 2012 (the Pembroke graph ends at 2011. sigh..). I have corrected the figure and the text that refers to it, but do not believe it affects the overall conclusion. See for yourself. Thanks Kevin — and Alan for getting in touch!

Another round of press release inspired news stories emerged last week insisting that polar bear predation on ground-nesting birds during the summer ice-free period is evidence that they are nutritionally stressed by global warming.

A few weeks ago it was snow goose eggs in Western Hudson Bay – this time it’s thick-billed murre (Uria lomvia) and common eider (Somateria mollissima) eggs in Foxe Basin and Hudson Strait (e.g. see the story at Canada’s National Post and a short summary provided by Science [and it’s not even their paper!]). The source of the media attention this time is a newly-published paper by Samuel Iverson and colleagues (Iverson et al. 2014).

Figure 1. From Iverson et al. 2014 (their Fig.1), “map of the study area.” Most of the study sites are within the Foxe Basin polar bear subpopulation region (see Fig. 2 below), although the Ungava Peninsula (E), Ungava Bay (F) and Frobisher Bay (C) sites are in the Davis Strait subpopulation.

Figure 1. From Iverson et al. 2014 (their Fig.1), “map of the study area.” Most of the study sites are within the Foxe Basin polar bear subpopulation region (see Fig. 2 below), although the Ungava Peninsula (E), Ungava Bay (F) and Frobisher Bay (C) sites are in the Davis Strait subpopulation.

Polar bears have always preyed on ground-nesting sea bird and goose eggs while onshore (see Kelsey Eliasson’s take on the situation around Churchill, at his PolarBearAlley blog). The issue in this case is whether the increase in predation can be unquestionably blamed on reduced sea ice cover and nutritionally-stressed bears – that is, predation increases that correlate with year-to-year sea ice changes and bears in poor condition found consuming bird eggs.

As I did for the “polar bears eat more caribou and snow geese than they used to” press release, I refused to take the PR or the news stories at face value and went to the published paper and its supplemental data (it’s open access, see it for yourself here).

What I see in this paper is a spurious sea ice correlation and no data on the condition of the few bears observed consuming eggs. There is also no mention of the fact that polar bear numbers have increased in part of the study area (Davis Strait) or that bears in Foxe Basin and southern Davis Strait have been found to be in very good condition and reproducing well (Rode et al. 2014; Peacock et al. 2013). See my analysis below and judge for yourself.

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Tracking polar bears in the Beaufort Sea: January map

Here is the January 2014 follow-up to my post on the July 2013 track map for female polar bears being followed by satellite in the Beaufort Sea by the US Geological Survey (USGS) – Ten out of ten polar bears being tracked this summer in the Beaufort Sea are on the ice.

See that post for methods and other background on this topic, and some track maps from 2012 (also available at the USGS website here).

The USGS track map for January 2014 is copied below (Fig. 1).

Both the Southern Beaufort and the Chukchi Sea were completely ice-covered by the end of January. The seven bears tracked during November and December were reduced to five in January — down 50% from the ten bears collared in July.
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Eat, wash up, repeat; eat, wash up, repeat…polar bears do it too!

Ah, that never-ending treadmill of meal preparation and cleanup. You might be surprised to find out that polar bears do it too.

Figure 1. How do polar bears look so clean most of the time when they get this bloody on a regular basis? They wash up! [This picture is not from Stirling’s paper].

Figure 1. How do polar bears look so clean most of the time when they get this bloody on a regular basis? They wash up!

I found an interesting description of polar bears washing during and after feeding, by a young Ian Stirling in one of his earliest published polar bear papers (Stirling 1974). At the time, he was observing polar bears on southwest Devon Island (74°43′ N; 91°10′ W, see Fig. 2 below) between 24 July and 8 August 1973. Even today, there’s ice for hunting seals in mid-to-late-summer in that part of Canada (Fig. 3).
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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

Polar Bear Specialist Group population status update is much ado about nothing

I cannot for the life of me fathom why the IUCN Polar Bear Specialist Group (PBSG) bothered to insert an announcement on their website back in mid-December, promising an updated polar bear status assessment, since the posted January 31 “update” is nothing of the sort — there have been no changes of any consequence.

It therefore appears I interpreted the oddly worded announcement incorrectly and none of the anticipated changes were forthcoming. Baffling, to say the least. Have a look at the new updated documents that were posted yesterday and see what you think.

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