Tag Archives: triplets

More Davis Strait polar bears onshore in the last two days

Four bears were photographed outside of Red Bay, Southern Labrador on Thursday 8 March and a bear was spotted ashore in NE Newfoundland overnight on Wednesday.

Red Bay Labrador polar-bears 8 March 2018_Vicki Hancock photo_CBC 9 March 2018

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Russia confirms Chukchi Sea polar bears not at risk from climate change or poaching

A statement yesterday from Yegor Vereshchagin, wildlife conservation manager from Chukotka, Russia  (Polar Bears Adjust to Climate Change, 20 February 2018) confirms that Chukchi Sea polar bears are currently doing extremely well.

Rode and Regehr 2010_Chukchi_report2010_Fig1_triplets_labelled

Contrary to previous reports and predictions (e.g. Amstrup 2011; Amstrup et al. 2007, 2008; Durner et al. 2009), there appears to be no threats due to recent declines in summer sea ice (Rode and Regehr 2010; Rode et al. 2013, 2014, 2018) or from poaching.
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New Chukchi Sea polar bear survey – exciting preliminary results

Back in October, I wrote about US Fish & Wildlife biologist Eric Regehr comments about a recent survey of Chukchi Sea polar bears, the results of which are still not published. Since then, I’ve been able to track down a bit of information.

This project appears to have run for five years, from 2008 to 2011. The work was confined to the eastern (US) portion of the Chukchi, see maps below (Polar Bear News 2010; Rode and Regehr 2010). Researchers were doing mark-recapture work with helicopters, putting radio collars on some females and radio ear tags on a few males. They worked primarily in March and April (mating season for polar bears), operating entirely on the offshore sea ice – working, I might add, on bears that technically speaking do not exist, since the official population estimate for this region is “zero” (they are not included in the global estimate of 20,000-25,000, see pdf here,, discussed here).

Figure 1. Chukchi Sea – getting you oriented. Note the location of Kotzebue Sound, northeast of the Bering Strait. Map from Wikipedia.

Figure 1. Chukchi Sea – getting you oriented. Note the location of Kotzebue Sound, northeast of the Bering Strait. Map from Wikipedia.

In 2012, US Fish & Wildlife biologist Eric Regehr told reporter Jill Burke at Alaska Dispatch that they found the bears were “reproducing well and maintaining good body condition.” I’ve finally found some details regarding what he meant by that statement (although no final reports or peer-reviewed papers are out, see footnote below).

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Extirpated polar bears of St. Matthew Island spent five months on land during the summer

Did you know there used to be resident polar bears on two small islands in the Bering Sea? Given how much we don’t know about the polar bears of the Bering Sea, the bears that used to den and spend their summers on the St. Matthew Islands are a bright spot. These islands lay at the southern-most limit of the modern “Chukchi Sea” subpopulation (see Fig. 1) and were uninhabited by people when they were discovered in the 1760s – but they were a haven for polar bears.

We have details of the polar bears that gave birth and summered there because a US government biologist (Henry Wood Elliott) and a US navy Lieutenant (Washburn Maynard) surveyed the islands in 1874. Elliott wrote both an official report and a popular magazine article (for Harper’s Weekly Journal of Civilization) in 1875 describing the polar bears they saw; Maynard wrote a separate report in 1876. By 1899, there were none left, victims of the relentless slaughter of polar bears everywhere in the Arctic in that era (see previous discussion here).

Figure 1. St. Matthew Island is in the Bering Sea off the west coast of Alaska: north of the Pribilofs and south of St. Lawrence Island, at about 60°N latitude. Compare this to the southern end of James Bay, Canada – which has a stable population of polar bears – at about 53 0N and Churchill, Manitoba – the “polar bear capital of the world” – at 58 046’N. Maps from Wikipedia.

Figure 1. St. Matthew Island is in the Bering Sea off the west coast of Alaska at about 60°N latitude. Compare this to the southern end of James Bay, Canada (which has a stable population of polar bears) at about 53 0N and Churchill, Manitoba (the so-called “polar bear capital of the world) at 58 046’N. Maps from Wikipedia.

Figure 2. A drawing of polar bears on St. Matthew Island that accompanied the May 1, 1875 Harper’s Weekly Journal of Civilization article written by Henry Elliot. See here.

Figure 2. A drawing of polar bears on St. Matthew Island that accompanied the May 1, 1875 Harper’s Weekly Journal of Civilization article written by Henry Elliot. See here.

[UPDATE: Jan. 27, 2013: a follow-up to this post is here.]

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Western Hudson Bay polar bears are not like the others – Part 2

In Part 1 of the Western Hudson Bay (WHB) polar bear story, I promised to explore the idea that rather than declining due to the effects of global warming, WHB polar bear populations may simply be returning to ‘normal’ after the rapid population increase that followed the intense over-harvests that occurred between 1890 and 1930 and again from 1945 to 1970.

Derocher and Stirling (1995:1664) had this to say about the life history features (like incidence of triplets and age of weaning) that made the polar bears of WHB unique:

The results of our analyses suggest that the unique reproductive characteristics of polar bears in western Hudson Bay in the 1960s and 1970s were either a function of a population increasing from a depleted state and feeding on a relatively abundant prey base, or density-independent fluctuations in prey population size, or availability due to sea ice variation.

In my last post, I discussed some of the evidence for how polar bear reproductive characteristics had changed since 1985. But how different were WHB polar bears, before and after 1985, from the other populations that had been dramatically reduced between 1890 and 1970, such as those in Svalbard/Barents Sea and Davis Strait?

There are two factors to consider in this recovery from over-harvest: population size changes and reproductive characteristics. Turns out, we don’t know much about the Davis Strait subpopulation but we do know a bit about Svalbard/Barents Sea bears since the 70s. And the Svalbard/Barents Sea vs. WHB comparison is a bit of an eye-opener.
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Western Hudson Bay polar bears are not like the others – Part 1

A review paper, purporting to list the “effects of climate warming on polar bears” (Stirling and Derocher 2012:2697), has this to say about the state of research in western Hudson Bay:

“The most comprehensive long-term research on polar bear demography, body condition, subpopulation size, abundance, and reproductive success has been conducted on the Western Hudson Bay subpopulation.”

This means that compared to all of the 19 subpopulations of polar bears (see fig. 1), the very best information we have is for Western Hudson Bay (WHB) bears (fig. 2).

But are western Hudson Bay polar bears biologically typical of all polar bears? In this post, I’ll begin to examine that question.

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