The newest polar bear science paper making the rounds courtesy the US Geological Survey, is a perfect example of a statistically-significant result with no biological significance. While the results are rather lame, the paper is dangerous because it repeats the disingenuous claim (see Crockford 2017) that Southern Beaufort Sea polar bear numbers declined in recent years due to summer sea ice loss.
The USGS authors (Durner et al. 2017) know this harm-from-summer-ice-loss assertion is not true for the Southern Beaufort subpopulation but the more papers they can get into print that say so, the more likely it will be believed — and the less likely readers will check older literature that documents the recent decline in polar bear numbers was due to a three year period (2004-2006) when thick ice conditions in spring made seal hunting a challenge, a repeat of a well-known phenomenon (e.g. Stirling et al. 1980; Stirling 2002) unique to this region that has been documented since the 1960s.
The Durner paper (USGS press release “Increased Sea Ice Drift Puts Polar Bears on Faster Moving Treadmill” published online 6 June ahead of print) spins the research results as potentially significant bad news but in so doing reveals how desperate they have become to make the public and their biology colleagues believe that Southern Beaufort polar bears, among others, are being negatively affected by summer sea ice loss (as per Stirling and Derocher 2012).
Durner, G.M., Douglas, D.C., Albeke, S.E., Whiteman, J.P., Amstrup, S.C., Richardson, E., Wilson, R.R. and Ben-David, M. 2017. Increased Arctic sea ice drift alters adult female polar bear movements and energetics. Global Change Biology. DOI: 10.1111/gcb.13746 http://onlinelibrary.wiley.com/doi/10.1111/gcb.13746/abstract [paywalled]
In fact, the Durner et al. paper does not document any harm to polar bears from the proposed ‘treadmill’ effect of more rapidly moving ice for the period 1999-2013 compared to 1987-1998, but instead uses models to suggest bears might have to eat one to three more seals per year to compensate for the extra energy needed to walk against the moving ice. That’s right: perhaps only 1 more seal per year out of the 50 or so they would usually consume (see Stirling and Øritsland 1995). In my opinion, that’s a pretty lame result for what one of the co-authors described as an immense amount of work.
News outlets have essentially used the USGS press release as a click-bait lede for another round of Trump-bashing with respect to the Paris climate change agreement, see here and here: the stories are hardly about polar bears at all. And predictably, polar bear activist and co-author Steven Amstrup (paid spokesperson for Polar Bears International, famous for their “Save Our Sea Ice” campaign) appears to be using the same approach: an up-coming call-in talk radio program at NPR’s Anchorage affiliate KSKA for Tuesday 13 June at 10:00 (Alaska time, see “Talk of Alaska”) is being billed as a discussion of “polar bears, climate change, and the Paris Accord” (h/t AK geologist). Continue reading
Posted in Advocacy, Conservation Status, Life History, Sea ice habitat
Tagged Alaska, Amstrup, Durner, endangered, energy, loss of summer ice, moving sea ice, polar bear, population decline, sea ice, seals, Southern Beaufort, spring feeding, summer sea ice, thick spring ice, threatened, treadmill, USGS
Relative to recent years and potential impacts on polar bear health and survival in Canada, there is nothing alarming in the pattern or speed of sea ice breakup for 2017, either over Hudson Bay, the southern Beaufort, or the eastern high Arctic.
Last year at this time (see map below), there was more open water in Hudson Bay and in the Southern Beaufort yet the polar bears came ashore in fine shape that summer and there was no hue-and-cry of dying bears anywhere. Breakup this year is on track to be about 3 weeks earlier than it was in the 1980s, as it has been since at least 2001, a conclusion reached by polar bear specialists (Castro de la Guardia et al. 2017; Lunn et al. 2016), who examined sea ice breakup to 2015.
Here are critical words to remember (more details here) from biologist Martin Obbard and colleagues (2016:29) on the relationship between body condition and sea ice for Southern Hudson Bay (SH) polar bears, which apply equally well to bears in other regions:
“Date of freeze-up had a stronger influence on subsequent body condition than date of break-up in our study. Though models with date of freeze-up were supported over models with other ice covariates, we acknowledge that lower variability in freeze-up dates than in ice duration or break-up dates could have influenced the model selection process. Nevertheless, we suggest that a stronger effect of date of freeze-up may be because even though break-up has advanced by up to 3-4 weeks in portions of Hudson Bay it still occurs no earlier than late June or early July so does not yet interfere with opportunities to feed on neonate ringed seal pups that are born in March-April in eastern Hudson Bay (Chambellant 2010). Therefore, losing days or weeks of hunting opportunities during June and July deprives polar bears of the opportunity to feed on adult seals, but does not deprive them of the critical spring period (Watts and Hansen 1987) when they are truly hyperphagic. No doubt, the loss of hunting opportunities to kill adult seals has a negative effect on body condition, but it appears that for bears in SH a forced extension of the fast in late fall has a greater negative effect on subsequent body condition.” [my bold]
In other words, by mid-June at least (maybe earlier), polar bears have largely finished their intensive feeding that’s so critical to their survival over the rest of the year.
That’s why the latest count of SH polar bears (Obbard et al. 2015) showed a stable population (and see this recent post on WHB polar population estimates). But freeze-up was late last year and that’s what will make the difference to polar bears over the coming year.
Posted in Conservation Status, Life History, Sea ice habitat
Tagged baffin bay, breakup, feeding, freeze-up, Hudson Bay, hunting, Kane Basin, polar bear, sea ice, snow cover, Southern Beaufort, spring feeding, trends
Last week biologist Andrew Derocher recently implied via twitter that less sea ice in the eastern portion of the Southern Beaufort (SB) this year at mid-May is harmful to polar bears (calling it “a hole in the ice where polar bears used to live“), but both long-term and short-term data don’t support such a glass-half-empty interpretation.
Not only does spring breakup of sea ice in the SB normally begin with such open patches of water (see the video above from last year) — driven by the powerful currents of the Beaufort Gyre, not ice melt (explained in detail here) — it may actually be necessary for the survival of local seals, polar bears and whales in spring and early summer (Citta et al. 2015; Crawford et al. 2015; Harwood et al. 2015; Stirling et al. 1981).
As I’ve pointed out before, the biggest threat to SB bears is thick sea ice in spring and its associated late breakup, a 2-3 year-long phenomenon unique to this region known to have occurred about every 10 years since the early 1960s (well documented in the scientific literature) but which has not (as far as I know) happened since 2004-2006.
In other words, a considerable patch of open water and less concentrated ice in the eastern SB around Cape Bathurst is almost certainly a good thing for this particular subpopulation (see previous post here for an in-depth discussion) because historically, when a polynya of some extent has not formed by April or May it has been devastating for local marine mammals.
The fact that an extensive patch of open water existed at mid-May in this region last year and the year before (2015 and 2016) — with no public hue-and-cry about a great dying of SB bears from Derocher or anyone else — suggests that open water in the eastern SB this year is likely to be beneficial for SB polar bears, or at least benign. Continue reading
Posted in Life History, Population, Sea ice habitat
Tagged bearded seals, Beaufort Gyre, Cape Bathurst, Derocher, hole in the ice, polar bear, polynya, ringed seals, sea ice, shore leads, Southern Beaufort, thick spring ice
A few days ago in a radio interview, a senior US Fish & Wildlife biologist repeated the tall tale that Southern Beaufort Sea polar bear numbers declined in recent years due to loss of summer sea ice. But restating this egregious misinformation does not make it true.
The Southern Beaufort population did decline between 2001 and 2006 but it was due to natural causes (thick ice in spring from 2004 to 2006) – it had nothing to do with recent summer sea ice loss and Eric Regehr knows it.
There is no evidence that the population decline continued after 2006, so it cannot be said to be still declining. Moreover, the situation in the Southern Beaufort does not support the predictions made by Regehr and his colleagues that polar bear populations will decline precipitously if summer sea ice declines further.
My recently published paper demolishes the message of doom for polar bears and the misinformation it’s based upon: it’s free and written in straight-forward scientific language.
Crockford, S.J. 2017. Testing the hypothesis that routine sea ice coverage of 3-5 mkm2 results in a greater than 30% decline in population size of polar bears (Ursus maritimus). PeerJ Preprints 19 January 2017. Doi: 10.7287/peerj.preprints.2737v1 Open access. https://peerj.com/preprints/2737/ (pdf here).
Here’s an excerpt of the nonsense broadcasted on KNOM Radio Alaska by Regehr and transcribed for their website (29 January 2017) [my bold]: Continue reading
Posted in Advocacy, Population, Sea ice habitat
Tagged advocacy, Eric Regehr, hypothesis testing, KNOM, misinformation, polar bear, poster child, predictions, Regehr, Southern Beaufort, US Fish and Wildlife Service
PBS has published a bizarre poor-starving-polar-bears story that uses pictures of fat, healthy bears to illustrate the supposed desperation of malnourished bears of the Southern Beaufort Sea that is blamed on declining sea ice.
The photo of the fat bear above, taken by the Kaktovik resident quoted in the 15 October 2016 PBS story, Polar bears, growing desperate for food, threaten native Alaskans, accompanies this statement:
“While images of malnourished polar bears have become a national symbol of the effects of climate change, they are a front line reality for Native Alaskans, who face them on their own property and do not want them to get hurt.”
Except this is not a story about starving bears but too many fat bears hanging around one particular community looking for other kinds of food – after being lured in by the enticing smell of rotting whale meat left onshore by the residents.
If photos of starving Beaufort bears existed that PBS could have used to illustrate this story, I’m certain those photos would have been used. But virtually all of the pictures I’ve seen of Kaktovik bears are the epitome of health – fat and sassy – but none that could be described as starving.
It turns out that while native Kaktovik residents have profited from tourists and journalist who have shown up in droves to view the large numbers of bears attracted to the bone piles left after butchering summer-caught bowhead whales, the bears have also put the community at risk of personal attack and loss of stored food. Who would have thought?
Residents of Kaktovik (see map below) have unwittingly enticed these polar bears ashore and now must deal with the consequences. As the residents of Churchill discovered decades ago, having polar bears close to your community comes with benefits, problems – and danger.
There is no doubt that Kaktovik has a polar bear problem but it cannot plausibly be blamed on anthropogenic global warming, retreating sea ice, or starving bears – an irresistible attractant close to the community is the cause and solutions must be found to keep residents safe and their food secure. The PBS article discusses a few of those solutions. Some quotes and background below.
Posted in Life History, Polar bear attacks, Sea ice habitat
Tagged Atwood, Barter Island, bone piles, climate change, desperate, facts, fat bears, global warming, Kaktovik, malnourished, polar bears, retreating sea ice, sea ice, Southern Beaufort, starving, stressed
Even though it is well known that subadult male polar bears (≤ 4 years old) continue to grow in mass and bulk as they mature – so that their thick necks get even larger – in recent years Andrew Derocher and his students at the University of Alberta potentially endangered the lives of many subadult males in the Southern Beaufort in the process of learning relatively little they didn’t already know.
Money quote from a just-accepted paper by Master’s student Jody Pongracz and supervisor Derocher (“Summer refugia of polar bears (Ursus maritimus) in the southern Beaufort Sea” Polar Biology, in press 2016):
“The number of bears tracked varied over time due to collar design, deployment, and both planned and unplanned collar retention.”
So, how much “unplanned collar retention” issues [collars that did not fall off as expected] went on during this 2007-2010 study? They don’t say.
Is this paper saying U of A researchers knew they had ‘collar retention’ issues as far back as 2010 but continued to deploy them on subadult males after that study was over? It seems so, because they had an issue with just such a bear last year.
The bear with an apparently tight collar that was photographed last fall (see photo above) went out onto the ice and no one knows what happened – there has been no more information on him since, although researchers have apparently been watching for him, updated just yesterday). The University of Alberta statement says (under the June 2 update):
“Ongoing research at the University of Alberta is shifting to ear tag radios as required”
So now they realize that putting collars on subadult males is not such a good idea. Brilliant!
CBC News (28 October 2015): “Photo shows polar bear injured by tight radio collar“. See previous posts here and here. In a Global News interview (23 November 2015), Derocher admitted his team had “likely” put the collar on that bear, prompting the University of Alberta to issue a “Q & A” statement on the incident – which continues to insist that failure of collars to release is “rarely seen.”
Posted in Life History, Sea ice habitat, Uncategorized
Tagged Andy, Derocher, failures, problems with collars, satellite collars, sea ice, Southern Beaufort, subadult males, thick spring ice, tight collar, University of Alberta
Take-home quote from a new polar bear paper by Todd Atwood and colleagues (2016):
“…there is no causal link between the patterns in polar bear vital rates and increased use of terrestrial habitat…”
In other words, there was no information to link the increased time polar bears spent onshore with either an increase or a decrease in body condition, survival or cub production. The authors did find that polar bears were strongly attracted to the bone piles that accumulated in the fall from 2010-2013 after Inuit bowhead whale (Balaena mysticetus) hunting at Barrow, Cross Island, and Kaktovik. Isn’t that a surprise?
The results also appear to confirm previous work that showed terrestrial (land-based) foods are not important to polar bears – a conclusion I totally agree with and which I discussed last year here. No wonder there was no press release issued by USGS about this study. It’s only “news” because someone the Anchorage Daily News interviewed lead-author Atwood yesterday as a way of promoting the International Bear Conference (see previous post here, now updated with a link to the Talk of Alaska radio podcast). Atwood implied there could be advantages to bears from feeding on the bone piles but admitted he had no data to support that assumption.
Posted in Advocacy, Life History, Population
Tagged Atwood, bone piles, Cross Island, decline, Kaktovik, polar bear, population size, sea ice, Southern Beaufort, terrestrial foods, whale carcasses