An article by CBC News today (3 March 2020) is a surprisingly well-balance report on a recently published paper by Kristin Laidre and colleagues on their work on Baffin Bay polar bears that I discussed last month. It presents the Inuit perspective that polar bears are currently abundant in the area and the population stable despite less summer sea ice and some documented declines in body weight and at least one scientist conceded this is indeed true.
However, the CBC writer still left out the most critical caveat included in the paper about the study: that factors other than changes in sea ice could have affected the body condition and litter size data that the authors documented but they didn’t look at anything except sea ice. This automatically means the conclusions are scientifically inconclusive.
See some quotes below from the CBC article and the caveat from the paper. Continue reading
Posted in Conservation Status, Population, Sea ice habitat
Tagged abundant, baffin bay, body condition, causation, caveat, correlation, polar bear, population size, sea ice, stable
Sea ice around Svalbard, Norway at the end of February 2020 is way above average, as the graph below shows – with more polar bear habitat now than there has been in two decades.
Some comparison charts below show that the graph above includes some very high ice years in the 1980s (reaching that dotted line above the mean) for which only global charts are available.
However, contrary to suggestions that more Svalbard ice is better for polar bears, there is no evidence that low extent of sea ice habitat in winter or summer over the last two decades harmed polar bear health, reproductive performance, or abundance. In fact, polar bear numbers in 2015 were 42% higher than they were in 2004 (although not a significant increase, statistically speaking) and most bears were found to be in excellent condition.
This suggests a return to more extensive ice to the Svalbard region in winter will have little impact on the health of the entire Barents Sea subpopulation, although it might change where pregnant females are able to make their maternity dens if ice forms early enough in the fall. In other words, the population should continue to grow as it has been doing since the bears were protected by international treaty in 1973.
UPDATE 3 March 2020: According to 28 February tweet by the Norwegian Ice Service, which I just saw today, “the last time there was this much sea ice around Svalbard on this day of the year [28 February] was 2004“. Somehow, I missed 2004 when I was looking through the archive, so I have modified the text below accordingly; see the 2004 chart below and here.
Posted in Life History, Population, Sea ice habitat
Tagged Barents Sea, body condition, cub survival, denning, facts, Franz Josef Land, polar bear, science, sea ice, Svalbard
A new paper on Baffin Bay polar bears reports data on body condition and litter sizes collected as part of a major study of the region completed in 2013 compared to sea ice declines since the 1990s; based on a computer model, the authors predict that in 37 years time (if sea ice declines continuously), the incidence of twin litters could “largely disappear.” However, no decline in population numbers was predicted and a critical caveat acknowledges that factors other than changes in sea ice could have affected the body condition and litter size data the authors analyzed, which means the conclusions are scientifically inconclusive.
The last (2013) polar bear population survey of Baffin Bay (SWG 2016) generated an estimate of almost 3,000 (2,826; range 2,059-3,593), which means that regardless of some slight changes in body condition and litter size over the last two decades (which may or may not have been caused by loss of sea ice), there are currently a lot of bears in Baffin Bay.
Posted in Conservation Status, Life History, Sea ice habitat
Tagged baffin bay, body condition, causation, correlation, extinction, fatness, Greenland, litter size, NASA, polar bear, sea ice, weight
This is week 15 for most polar bears onshore near Churchill in Western Hudson Bay, which means they have been onshore for almost 4 months. Still, photos being circulated are still showing bears in excellent condition and we are just waiting to see if freeze-up this year is as early as it has been for the last two years.
Polar bear researcher Andrew Derocher says it takes four years of good sea ice conditions to recruit a polar bear from birth but implies that 2019 is the first year in decades that conditions for bears have been ‘good’ in Western Hudson Bay. He thinks he can get away with saying this because he hasn’t published any of the data on body weight and body condition he’s collected on these bears over the last 25 years (apparently, whatever funding agency pays for his research does not require him to publish the data he collects).
But independent observations such as dates of ice freeze-up in fall, ice breakup in summer, dates and condition of bears recorded onshore, suggest he’s blowing smoke: at least five out of five of the last sea ice seasons for WH bears have been good. That means we should be seeing more bears in the next official population count.
Posted in Advocacy, Conservation Status, Polar bear attacks, Sea ice habitat
Tagged body condition, breakup, Derocher, fat bears, freeze-up, Hudson Bay, polar bear, sea ice, thriving
Earlier this year, I challenged a journalist to ask to see the data used by Andrew Derocher and his colleagues to support their repeated claims that Western Hudson Bay polar bears are having trouble surviving. It almost happened.
David Rose, writing for The Mail on Sunday, has produced an excellent feature on the conflict between Nunavut Inuit and biologists about polar bear management, got Andrew Derocher to tell the truth about current polar bear health and survival.
Or, to be more precise, to waffle a bit on his standard message of doom:
“Even Prof Derocher, who is convinced the bears’ long-term future is bleak, accepts that ‘the wheels are not coming off yet’, while ‘some bear populations are doing fine’. In West Hudson Bay, there has been ‘a recent period of stability’, he says, and though ‘we were seeing starving bears, starving cubs on land, that seems to have slowed down’. Then again, the computer models ‘are not great on the 5 – 10 year time-frame’, and it was possible that although the Arviat bears might look healthy now, they may be about to ‘fall off a cliff’.” [my bold]
This concession by Derocher suggests that Western Hudson Bay bears indeed are thriving, because he’s the guy who holds all the data. But he couldn’t help adding that disaster might be just around the corner.
But did he actually produce the data that show what’s been happening with cub survival or the body condition of females since 2004? Apparently not — but his admission that conditions are not as bleak as he continually portrays them suggests he is covering for data that says the same: polar bears in Western Hudson Bay are doing just fine and Inuit are right to be worried.
This may be as good as it gets unless the people of Nunavut can force Derocher to show his data.
Read the whole story here: “Why all you’ve been told about these polar bears could be WRONG: Animals driven to the edge of their natural habitat by shrinking ice have become one of the defining images of climate change, but Inuits who know the predators have a very different story.” (The Mail on Sunday, David Rose, 30 December 2018).
Posted in Conservation Status, Polar bear attacks, Population
Tagged Arviat, attacks, body condition, cub survival, Derocher, estimates, fat, Hudson Bay, polar bear, population, problem bears, sea ice
The Chukchi Sea finally has a polar bear population estimate! According to survey results from 2016 only recently made public, about 2937 bears (1522-5944) currently inhabit the region, making this the largest subpopulation in the Arctic. This is exciting news — and a huge accomplishment — but the US Fish and Wildlife Service responsible for the work has been oddly mum on the topic.
Not only that, but an extrapolation of that estimate calculated by USFWS researchers for Chukchi plus Alaska (the US portion of the Southern Beaufort Sea subpopulation) was estimated at 4437 (2283-9527), although with “significant uncertainty.” Nevertheless, it means the 2016 estimate for Alaska could be roughly three times what it was in 2010: a whopping 1500 or so, up from about 450 (or about 225-650) for the same area estimated during the last survey (Bromaghin et al. 2015: Fig. 5a).
Even if the real number for Alaska is only twice as large (~1000), that’s still a huge improvement. It would eliminate the Southern Beaufort as the only polar bear subpopulation in the Arctic to have shown a significant decline blamed on human-caused global warming (Crockford 2018). If the recovery is real, it means the 2004-2006 decline was a temporary fluctuation after all, just like previous declines in the region. I expect, however, that it will take a dedicated SB population survey for officials to concede that point.
not yet now a detailed report to cite (Regehr et al. 2018 in prep, see update below), but the numbers were announced at the 10th meeting of the Russian-American Commission on Polar Bears held at the end of July this year (AC SWG 2018) by Eric Regehr (formerly of the US Fish & Wildlife Service, as of 2017 at the University of Washington). [h/t to G.H.] This was the same report that raised the quota for subsistence hunting in the Chukchi from 58 to 85, based on these new figures, as I discussed last week.
From “Military bases to open on Wrangel Island and Chukotka” 22 October 2015.
Regehr was quoted as saying:
“Chukchi bears remain larger and fatter and have not seen downward trends in cub production and survival, according to new preliminary information on the health and numbers of bears.”
UPDATE 15 November 2018: The scientific paper describing the entirely new method (yes, yet another one: see Bromaghin et al. 2015) used to estimate the size of the Chukchi Sea population is now available (University of Washington press release here), in an open-access paper: Regher et al. 2018. News reports (see one here) spin the positive outcome as something that researchers expected all along but that’s simply not true. They expected Chukchi Sea bears and Southern Beaufort Sea bears to respond similarly to reduced amounts of summer sea ice, as explained here and in Crockford 2017).
Posted in Conservation Status, Population
Tagged Alaska, body condition, Chukchi Sea, cub survival, fat bears, guesstimate, healthy, increase, polar bear, population, Regehr, sea ice, Southern Beaufort, thriving, triplets