Headline run by The Independent last Friday (20 July 2018):
‘A death sentence for polar bears’: Trump administration seeks changes to endangered species protections: Conservation groups are already vowing to sue the Donald Trump administration if the revisions go into effect
Such over-the-top rhetoric is as predictable as puddles after a cloud-burst (see a statement by the WWF here, and the Center for Biological Diversity (source of the “death sentence for polar bears” claim here) but the proposed changes only apply to future listings, not listings already in place. See the USFWS press release below.
However, both The Independent and ABC News featured polar bears in their stories, a species listed as threatened in 2008.
It would be hard to beat the irony of ABC: it ran video of fat Kaktovik polar bears behind their anchor as he delivered the ESA story. The Independent not only used the “death sentence to polar bears” quote but included the video clip from last year of the dying Baffin Island bear even though it is very likey the bear was emaciated due to cancer rather than lack of food (Crockford 2018).
Why would anyone mention polar bears? Why is the Center for Biological Diversity so afraid?
Because if polar bears face a delisting challenge, the new rules apply.
Posted in Advocacy, Conservation Status, Population, Sea ice habitat
Tagged delisting, endangered, ESA, foreseeable future, polar bear, proposed changes, sea ice, threatened, US Fish and Wildlife Service
Last week’s media coverage made me realize that James Hansen’s testimony to a US Senate committee in 1988 provided well-timed answer to a vexatious problem facing polar bear biologist Ian Stirling. Thirty years ago, Stirling was struggling to understand why polar bear productivity in Western Hudson Bay had dropped. He was ripe for the suggestion from Hansen (and his follow-up paper) that human-caused global warming could be the explanation. An interview with Stirling and colleague Andrew Derocher published in 2016 helps connect the dots.
Many bears were in poor condition in the fall of 1983 (Calvert et al. 1986:19, 24; Ramsay and Stirling 1988). In general, the 1980s saw weights of bears decline and cub mortality increase, with a marked increase in the loss of whole litters over what had been documented in the 1960s and 1970s (Derocher and Stirling 1992, 1995).
Until Hansen and climate change came along, density-dependent effects (such as the number of bears out-pacing food supply) were seen as the most likely explanation. But sea ice decline blamed on human-caused global warming was suddenly a new possibility that Stirling soon embraced (Stirling and Derocher 1993). By the late 1990s, sea ice coverage on Hudson Bay had indeed declined but the correlation with polar bear productivity produced a weak trend that was not statistically significant (Stirling et al. 1999).
The 1999 Stirling paper did not provide scientific evidence to explain the 1980s decline in productivity as much as it presented a novel scapegoat to blame when a more plausible explanation could not be made.
Bottom line: Global warming could not have been the proximate cause of the productivity changes in WH polar bears documented during the 1980s but Stirling spent the next two and a half decades vigorously pushing climate change as the cause of all polar bear ills. Continue reading
Posted in Conservation Status, Life History, Population, Sea ice habitat
Tagged body condition, climate change, decline, density-dependent response, global warming, Hansen, natality, polar bear, productivity, sea ice, Stirling, survival
Wednesday 21 June is the longest day of the year: wear something white tomorrow to acknowledge and celebrate the success of polar bears despite such low summer sea ice since 2007 that 2/3 of them were predicted to disappear.
White tie, white shirt, white socks work too. Keep cool and signal to the world that you love outstanding survivors of climate change, fat though they may be.
Read here and here.
Global sea ice extent at 19 June 2018, well past the end of the intensive spring feeding period for polar bears:
Just out (6 June 2018) — new population assessment and status maps of the 19 polar bear subpopulations according to Environment Canada. Contrary to the map presented at the Range State meeting in February 2018 (pdf here), these maps show Western Hudson Bay and Southern Hudson Bay (along with the Southern Beaufort) as “likely declined.” A new category has been added for the Barents Sea: it’s considered “data deficient/uncertain,” but a population estimate of 2,001-3,000 has been provided.
No press release or other notice regarding the availability of these new maps was issued, as far as I know: I came across them by accident while looking for something else.
Global map above, more below, including a comparative map that shows 2010, 2014, and 2018 together. I will update the two recent posts of mine (here and here) that used the February Range State map with the information that more recently revised maps are now available.
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.
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
Posted in Conservation Status, Life History, Population, Sea ice habitat
Tagged body condition, capture, Derocher, fat, field work, Lunn, mark-recapture, mass, polar bear, protocol, Sciullo, sea ice, Stirling, unpublished data, weight, western hudson bay
A newly-published paper by Martyn Obbard and colleagues in the journal Arctic Science claims a 17% decline in abundance of polar bears in the Southern Hudson Bay region after years of reduced sea ice and declining body condition (Obbard et al. 2018). The decline in numbers was not statistically significant but an additional statistical analysis (“Monte Carlo simulation”) not applied to any other estimate in recent years suggested the decline could be real, so a real decline is what was reported to the press.
Only one Canadian Press story has so far been circulated amongst outlets in the media (published hours after the paper appeared online, not at the same time), suggesting there was no press release issued for this study. Odd, that — especially if the decline is as real and significant as the authors suggest.
While no evidence was provided for a correlation of this decline in numbers to recent (2012-2016) sea ice decline, previous evidence from the region (Obbard et al. 2016) showed a decline in body condition was correlated only with much later than usual freeze-up, a situation that did not occur from 2012 to 2015 (freeze-up was late in the fall of 2016 but occurred months after the Obbard et al. (2018) survey was completed).
Moreover, the paper reports that a decline in survival of yearling cubs (from 12% of the population in 2011 to 5% in 2016) was not associated with especially poor sea ice conditions in spring. We are likely to see a follow-up paper next year reporting the body condition and sea ice data from this study (as for the previous survey: Obbard et al. 2015, 2016), but there is no suggestion in this paper that body condition declined further from 2011/2012 levels or that sea ice conditions deteriorated markedly enough after 2012 to precipitate a population decline.
UPDATE 11 June 2018: See below, more recent versions of population and status assessment maps has been issued by Environment Canada that conclude Southern Hudson Bay is “likely declined.”