Tag Archives: Derocher

No extirpation looms for Svalbard polar bears: no pending catastrophe in Norway

Despite a wild claim that a “slow Arctic freeze” this year increases the risk that polar bears will become extinct, sea ice charts show ice returning earlier than it has for decades everywhere except the Svalbard area of the Barents Sea. That’s good news for pregnant polar bears. Although Svalbard is without ice, that’s been true for so many years that pregnant Svalbard females long ago abandoned the use of islands they used in good ice years and now make their dens in the Franz Josef Land archipelago to the east (which is still within the Barents Sea subpopulation region).

Svalbard polar bear fall 2015_Aars

Polar bears give birth around 25 December each year, so pregnant females prefer to be snug in a safe den by around the end of November at the latest. That’s been possible for all regions of the Arctic this year, including the Barents Sea — because sea ice returned to Franz Josef Land weeks ago, even though Svalbard is still ice-free.

Franz_Josef_Land_location_wikipedia

Major denning areas in Russia, including Wrangel Island, have been surrounded by ice since the middle of the month, allowing pregnant females that did not remain on shore over the summer to return to make maternity dens. Elsewhere, bears that have been confined to shore over the ice-free season (such as along Hudson Bay and Baffin Island in eastern Canada) returned to the ice to hunt seals weeks ago after the earliest freeze-up in more than two decades.

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Nunavut government has a draft plan to deal with unsafe numbers of polar bears

In the news today: “Nunavut Draft Plan Says There Are Actually Too Many Polar Bears In Territory” (CTV News via The Canadian Press, Bob Weber, 12 November 2018).

Polar Bear seaweed_Lorraine Brandson Churchill_taken Nov 2012

Polar bear eating seaweed near Churchill, Manitoba (November 2012). Lorraine Brandson photo.

From the Canadian Press story:

“There are too many polar bears in parts of Nunavut and climate change hasn’t yet affected any of them, says a draft management plan from the territorial government that contradicts much of conventional scientific thinking.

The proposed plan — which is to go to public hearings in Iqaluit on Tuesday — says that growing bear numbers are increasingly jeopardizing public safety and it’s time Inuit knowledge drove management policy.

“Inuit believe there are now so many bears that public safety has become a major concern,” says the document, the result of four years of study and public consultation.”

I’ve noted previously that there were two fatal polar bear attacks in Hudson Bay this summer. Both of them happened outside local communities and both happened early during the ice-free period (when bears would have been onshore for only a few weeks). Neither incident can be reasonably blamed on lack of sea ice, an extended ice-free period, or lack of management of problem polar bears within or near communities. The bears involved in the August attack were described as being in good condition.

Update 13 November 2018: See The Guardian‘s take on this story, by a different writer. Despite potential to talk to other polar bear specialists about this issue, only Derocher is quoted. Is no one else talking? “Polar bear numbers in Canadian Arctic pose threat to Inuit, controversial report says” (The Guardian, 13 November 2018).

Update 14 November 2018: See a new CBC story on Inuit perspectives on this issue. “Nunavut community says Inuit lives need to be protected over polar bear population” (CBC News, 14 November 2018).

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Svalbard polar bear data 2016 through 2018 shows no impact of low ice years

Last week, the Norwegian Polar Institute updated their online data collected for the Svalbard area to include 2017 and 2018 — fall sea ice data and spring polar bear data. Older data for comparison go back to 1993 for polar bears and 1979 for sea ice, showing little to no impact of the reduced ice present since 2016 in late spring through fall.

Svalbard polar bear_NP015991-isbjorn-JA

Here’s what the introduction says, in part [my bold]:

“…The polar bear habitat is changing rapidly, and the Polar Basin could be ice-free in summer within a few years. Gaining access to preferred denning areas and their favourite prey, ringed seals, depends on good sea ice conditions at the right time and place. The population probably increased considerably during the years after hunting was banned in 1973, and new knowledge indicates that the population hasn’t been reduced the last 10-15 years, in spite of a large reduction in available sea ice in the same period.”

See Aars et al. 2017 for details on the 2015 Svalbard polar bear population count, keeping in mind that the subpopulation region is called “Barents Sea” for a reason: only a few hundred individuals currently stick close to Svalbard year round while most Barents Sea bears inhabit the pack ice around Franz Josef Land to the east (Aars et al. 2009; Crockford 2017, 2018).
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Critical evidence on W Hudson Bay polar bears still not published after 25 years

Polar bear researchers have been doing capture/recapture studies in Western Hudson Bay for decades yet most of the data claimed to be critical for assessing effects of human-caused global warming on this species have not been published. I raised this point in one of my early blog posts (27 Sept 2012) but the situation has not changed in 6 years. Here’s an update.

Derocher in the field in WH_CBC story 2016

From CBC story 14 Sept 2016.

Years ago now, in an oft-cited paper, Stirling and Derocher (2012) claimed to summarize the evidence that climate warming was negatively impacting polar bear health and survival. Several life history parameters were considered crucial, particularly body condition.

Despite almost a dozen papers (and perhaps more) on various aspects of WH polar bear health and life history studies based on capture/recapture data published since 2004  (e.g. Castro de la Guardia 2017; Lunn et al. 2016; Pilfold et al. 2017), none have reported the body condition data that supposedly support the claim that sea ice loss is having a severe impact — and the same is true for litter size, proportion of independent yearlings, and cub survival.1

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Polar bear numbers, margins of error, & consequences for conservation status

Large margins of error in polar bear population estimates means the conservation status threshold of a 30% decline (real or predicted) used by the US Endangered Species Act and the IUCN Red List is probably not valid for this species.

Polar_Bear_Biologist_USFWS_working_with_a_Bear_Oct 24 2001 Amstrup photo

Several recent subpopulation estimates have shown an increase between one estimate and another of greater than 30% yet deemed not to be statistically significant due to large margins of error. How can such estimates be used to assess whether population numbers have declined enough to warrant IUCN Red List or ESA protection?

What do polar bear population numbers mean for conservation status, if anything?

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Polar bear specialist Mitch Taylor on accountability in polar bear science

Polar bear specialist Mitch Taylor emailed me and others his response to the New York Times article that appeared Tuesday (10 April) about the Harvey et al. (2018) BioScience paper attacking my scientific integrity. Here it is in full, with his permission, and my comments. Don’t miss the footnote!

Mother with cubs Russia_shutterstock_71694292_web size

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Polar bear population numbers are for kids, says specialist Andrew Derocher

Polar bear specialists made global population numbers the focus of the world’s attention when they predicted a dramatic decline and possible extinction of the species. But now that the numbers have increased slightly rather than declined, the same scientists say global numbers are meaningless: the public should give those figures no credence and anyone who cites global population numbers should be mocked.

NBC 2015_3 there will soon be a big decline in polar bear numbers snap

See the screen shot from a 2015 NBC news video above and another from the science journal NATURE in 2008 below (Courtland 2008):

Courtland 2008 headline

Yet, below is a recent message from one of the world’s most vocal polar bear specialists, four years after a similar incident raised the public’s ire:

Derocher tweet 2018 Feb 28 quote

However, you can’t make a plausible prediction of future survival without an estimate of present population size: not even today’s worst journalists would buy it, nor should they.
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