Monthly Archives: December 2012

Bearded and ringed seals join the polar bear as “threatened” by a computer-modeled future

Posted on December 30, 2012 | Comments Off on Bearded and ringed seals join the polar bear as “threatened” by a computer-modeled future

As I pointed out in Featured Quote #22 (posted on Dec. 23, 2012), bearded and ringed seals have recently joined the polar bear on the American ESA’s list of animals that are “threatened” by computer-modeled predictions of Arctic sea ice declines projected 50-100 years into the future (USFWS 2008, 2012a, 2012b).

NOAA photos of bearded seal (top) and ringed seal (bottom)

NOAA photos of bearded seal (top) and ringed seal (bottom). The bearded seal is one of the largest Arctic ice seal while the ringed seal is the smallest. Both are eaten by polar bears, although ringed seals are consumed most often.

The decision by NOAA (National Oceanographic and Atmospheric Administration) affects the Arctic subspecies of ringed seal (Phoca hispida hispida) as well as the Okhotsk subspecies (Phoca hispida ochotensis) (in addition to several others) and thus includes all ringed seals off Alaska’s coast in the Beaufort, Chukchi and Bering Seas. The decision also affects two particular subpopulations of bearded seal (Erignatha barbatus): the “Beringia” [Bering Sea/Chukchi] subpopulation (about half of which reside in Alaskan waters), and the subpopulation that lives in the Sea of Okhotsk. (Alaska Fisheries (NOAA) Final Decision). Continue reading

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Posted in Conservation Status, Sea ice habitat

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Did the PBSG game the polar bear listing process?

Posted on December 26, 2012 | Comments Off on Did the PBSG game the polar bear listing process?

I was in the process of writing about something else last week when I came across a tidbit of information that, on closer examination, turned out to be part of a much bigger issue that I thought should be documented.

The story involves some machinations behind the scenes of the international Polar Bear Specialist Group, the “PBSG,” that you might find rather astonishing – and which may have implications for the various on-going battles about the polar bear’s conservation status.

A lone polar bear walking on ice [Kathy Crane (NOAA) photo]. We'll call this a metaphor for the expulsion of Mitch Taylor from the PBSG after the Group switched from emphasizing unregulated over-hunting as the primary threat to polar bear conservation to global warming.

A lone polar bear walking on ice [Kathy Crane (NOAA) photo].
We’ll call this a metaphor for the expulsion of Mitch Taylor from the PBSG,
after the Group switched from emphasizing unregulated over-hunting
as the primary threat to polar bears to global warming.

Continue reading

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Posted in Conservation Status, Population

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Merry Christmas

Posted on December 24, 2012 | Comments Off on Merry Christmas
My rendition, in gingerbread, of three polar bears on an iceberg. Happy holidays to you all.

My rendition, in gingerbread, of three polar bears on an iceberg.
Happy holidays to you all.

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‘Species-threatening’ population declines vs. polar bear declines

Posted on December 16, 2012 | Comments Off on ‘Species-threatening’ population declines vs. polar bear declines

In 2008, polar bears in the United States were declared ‘threatened’ under the Endangered Species Act (USFWS 2008). The IUCN (to which the Polar Bear Specialist Group (PBSG) belongs) lists the polar bear as “vulnerable” (IUCN Red List 2012). In Canada (where 60% of the world’s polar bears reside), the polar bear is listed as a ‘species of special concern’ (COSEWIC 2008:iii).

As Jonathan Adler pointed out in an excellent article that appeared on the heels of the American ESA listing decision (Adler 2008:112), “Insofar as the listing is based upon climate models, ice-melt projections, and assumptions about the effects of habitat loss on the bear’s prospects for survival in the wild, its scientific basis is quite speculative.” These are also, as I understand it, unprecedented criteria for ESA listing – no other species has been listed as endangered or threatened based on such speculation of future conditions.

So what do actual polar bear population declines look like?

The Western Hudson Bay, Canada (WHB) subpopulation is the only one that has recently declined by a statistically-significant amount. [see previous post here on the status numbers] The WHB polar bear subpopulation makes up 3-5% of the global total for the species, currently estimated at 20,000-25,000 animals.

In this post, I’ll compare the documented WHB population decline to the declines seen in a few truly endangered animals, just to put the much-bandied about numbers into some perspective. Continue reading

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December is Polar Bear Nativity Month

Posted on December 12, 2012 | Comments Off on December is Polar Bear Nativity Month

Polar bears are generally out of sight at this time of year and will be for several more months. Pregnant females will be snug in maternity dens giving birth and all others will be out on the sea ice looking for seals to eat – if they can find them in the dark.

In most areas of the Arctic, December is when polar bear cubs are born, although in southern regions (like Western and Southern Hudson Bay), some may be born in late November and in the far, far north, a few may be born as late as early February.

The actual “date of birth” for polar bear cubs is often back-calculated from when they emerge with their mothers in the spring, because they are born well away from our prying eyes in the dark of the Arctic winter, deep with a snow or soil den dug for that purpose (see previous post here). So our knowledge of the “true” dates of birth in various regions is limited. We have some evidence from native Canadian hunters prior to 1968, when it was both legal and common practice in Canada for Inuit to hunt bears in their dens (Van de Velde et al. 2003), and from a few scientific research expeditions (Amstrup and Gardner 1994; Harington 1968; Ramsay and Stirling 1988; Derocher et al. 1992).

Polar bear cubs, like all bears, are born tiny and rather undeveloped (see Figs 1 and 2 below). Their eyes do not open until about one month after birth. By the time they are 63 days old (two long months after birth, see Toronto Zoo photo here ), their eyes are wide open and they are well furred. Keep in mind, for perspective, that domestic dogs are born after a 63 day gestation period and their eyes open at about 12 days.
Continue reading

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Posted in Life History

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Now that Bering Sea ice cover is high again, variability is normal

Posted on December 10, 2012 | Comments Off on Now that Bering Sea ice cover is high again, variability is normal

Sea ice development in the Bering Sea is trending higher than average again this year, even though it is early in the season. The NSIDC sea ice extent image for Dec 6 2012 below (Fig. 1) shows extensive ice development in the Bering Sea. [courtesy WUWT sea ice reference page]

“Seven of the last 10 years have produced above-average freezing in the waters west of Alaska” says Kathleen Cole of the Alaska National Weather Service (Dec. 6, 2012) – see “Featured Quote” #20 in the right column (also filed in the “Quote Archive“).

Fig. 1 National Snow and Ice Data Center (NSIDC) sea ice extent at Dec. 6 2012. The orange line is the median extent for this date for 1979-2000.

Figure 1. NSIDC sea ice extent at Dec. 6 2012.
The orange line is the median extent for this date for 1979-2000. Click to enlarge.

The NSIDC, in their report on the annual freeze-up of the Arctic (November 2012), have this to say about the ice in the Bering Sea:

“…ice extent in the Bering Sea by the end of the month was greater than average, continuing a pattern seen in recent years. Extent in the Bering Sea was at record high levels last winter.”
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More evidence that the polar bear is a distinct species

Posted on December 6, 2012 | Comments Off on More evidence that the polar bear is a distinct species

Most people would not question the species status of the polar bear (Ursus maritimus). While it is true that polar bears – under certain circumstances – have successfully interbred with brown bears (aka ‘grizzlies,’ Ursus arctos)[see previous post on hybridization], there are many characteristics that distinguish each of these species as unique entities (see diagram below).

Grizzly vs polar skulls composite

Now, new genetic evidence adds weight to the balance on this issue. In this post, I’ll discuss very briefly the implications of this new paper:

Cronin, M. A. and MacNeil, M. D. 2012. Genetic relationships of extant brown bears (Ursus arctos) and polar bears (Ursus maritimus). Journal of Heredity 103 (6): 873-881. doi:10.1093/jhered/ess090 http://jhered.oxfordjournals.org/content/103/6/873.abstract

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Posted in Evolution, Hybridization

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