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capture, Derocher, fat, field work, Lunn, mark-recapture, mass, polar bear, protocol, Sciullo, sea ice, Stirling, unpublished data, weight, western hudson bay
I know I was not the only one that thought the last polar bear count conducted by the US Geological Survey (USGS) in the Southern Beaufort generated an untenable result but it appears that some of those challengers are in a position to demand a recount.
CBC News ran a story late last week announcing a plan is in the works to do an aerial survey of Southern Beaufort Sea polar bears across their entire range over two years starting in 2017 (11 March 2016, “Joint U.S.-Canada Beaufort Sea polar bear survey planned“).
With luck, this period will not include another bout of the same thick spring ice conditions that decimated the population in the mid-2000s (which many reporters concluded was due to reduced summer sea ice because that’s what leading biologists implied). Even if it does, lucky timing will not negate the fact that this population is routinely subjected to devastating population declines caused by natural changes to spring sea ice conditions from which they have recovered on numerous occasions. Continue reading
Posted in Conservation Status, Population, Sea ice habitat
Tagged aerial survey, Alaska, Arctic, Beaufort Sea, facts, hunters, Invuialuit, mark-recapture, Northwest Territories, polar bear, population estimate, sea ice, traditional knowledge
In a polite but misleading article today in a BBC magazine (The polar bears are coming to town) about the relationship of polar bears and Inuit in Arviat, Western Hudson Bay, there is no mention of the on-going feud between Nunavut Inuit and Canadian polar bear scientists regarding invasive research.
Nor is there a mention of the fact that according to the most recent research, there has been no trend in sea ice conditions since 2001.
Posted in Polar bear attacks, Population, Sea ice habitat
Tagged Arviat, BBC, breakup, freeze-up, invasive research, Lunn, mark-recapture, Nunavut, polar bear, sea ice, Tyrrell, western hudson bay
Did we hear a huge hue and cry in 2013 about starving polar bears and low cub survival in the Southern Beaufort Sea? No, we did not. Despite the record-breaking low summer sea ice extent the year before (2012), and despite the fact that USGS biologists were putting collars on polar bear females there the spring of 2013 (Rode et al. 2014), we heard not a peep about a polar bear catastrophe in the Southern Beaufort. Odd, isn’t it?
Several polar bear biologists and sea ice experts were busy late last fall suggesting to the media that a decline in polar bear numbers in the Southern Beaufort was due to declines in summer sea ice, which they blamed on global warming (see quotes below and earlier discussions here, here and here). However, they made no mention of the fact that the record-breaking September ice extent in 2012 did not seem to have any noticeable effect on polar bear health or survival in 2013.
Sea ice maps from the National Snow and Ice Data Center (NSIDC) tell most of the story about what the media were, and were not, told about summer sea ice in the Southern Beaufort between 2001 and 2013. Continue reading
Posted in Advocacy, Population, Sea ice habitat
Tagged abundance, aerial survey, Amstrup, Beaufort Sea, Bromaghin, Mark Serreze, mark-recapture, polar bear, population estimate, population recovery, Red list, Rode, sea ice, Southern Beaufort, spring ice conditions, summer ice minimum, USFWS
NOAA’s list of purported evidence for harm being caused to polar bears by Arctic warming is short and weak. It puts the gloomiest spin possible on the current well-being of an animal with all the earmarks of a healthy, well-distributed species.
This year, polar bears are virtually the only species that NOAA mentions in their Arctic Report Card – they’ve put all their icon-eggs in one leaky basket [what happened to walrus??]. But polar bears are doing so well that to make an alarming case for polar bears as victims of Arctic warming, many important caveats had to be left out or misrepresented. Some details given are simply wrong.
This year’s polar bear chapter was penned by IUCN Polar Bear Specialist Group chairman Dag Vongraven (you might recall his email to me earlier this year) and a polar bear conservation activist from Polar Bears International (whose battle cry for donations is “Save Our Sea Ice!”), Geoff York.
I challenge their four weak talking points one by one below.
Posted in Population, Sea ice habitat, Summary
Tagged Arctic, Arctic Report Card, breakup, Bromaghin, cherry-picking, freeze-up, Geoff York, hybridization, IUCN Polar Bear Specialist Group, mark-recapture, polar bear, population estimate, red herring, sea ice, Southern Beaufort, thick spring ice, USFWS, Vongraven, western hudson bay
Apparently, some biologists think that outputs from complex computer models will convince native Arctic residents that invasive mark-recapture work has no long-term effect on the health and well-being of polar bears.
Posted in Uncategorized
Tagged Amstrup, Bromaghin, Government of Nunavut, handling, Inuit, invasive research, mark-recapture, models, observations, Peacock, polar bear, Rode, satellite collars, tranquilizer drugs
New evidence has come to light that mark-recapture field work used to calculate a new population estimate for Southern Beaufort polar bears did not conclude in 2010 as implied in a widely-publicized paper last month but continued until 2013.
Steve Amstrup in S. Beaufort, 2005 (USGS photo), co-author of Rode et al. paper.
As I discussed previously, last month’s widely-hyped paper (Bromaghin et al. 2015
in press) – which reported a decline of ~40% between 2004 and 2010 (based on spring mark-recapture work) – was contradicted by fall survey counts that suggested strongly a population rebound would have been apparent if the mark-recapture work had continued another two years.
A new paper by Karyn Rode and colleagues (which includes Bromaghin and others (e.g. Amstrup) from the previous paper), summarized in a USGS press release issued on Monday and published online Tuesday, utilized comprehensive data collected during mark-recapture work carried out in spring from 1982 to 2013 in the Southern Beaufort Sea.
This new paper used the same kind of comprehensive data as Bromaghin and colleagues – from the same season, in the same region – to assess potentially negative effects of the mark-recapture research method itself, up to 2012 and beyond.
More on the Rode et al. conclusions later1 – for the moment, what is important is that the work described in the paper confirms that spring mark-recapture work on polar bears in the Southern Beaufort continued beyond 2010. Bromaghin and colleagues didn’t end their mark-recapture work prematurely — they actually left data collected in 2011 and 2012 out of their population estimate analysis when they had to have known the population had not finished rebounding from the 2004-2006 decline.
Posted in Advocacy, Conservation Status, Population
Tagged abundance, aerial survey, Amstrup, Beaufort Sea, Bromaghin, cherry-picking, IUCN, mark-recapture, models, PBSG, polar bear, population estimate, population recovery, Red list, Rode, satellite collars, sea ice, Southern Beaufort, USFWS, withholding data