Monthly Archives: September 2021

Fat polar bear of late summer in Arctic Canada

Retired Mountie and bird photographer Clare Kines captured on film one of those ‘canaries of in the coal mine’ of the Canadian Arctic we hear so much about. Kines is from Arctic Bay and took the photo a few weeks ago, on 9 September, on the north end of Baffin Island (just east of where the famous National Geographic ‘starving’ bear was filmed in 2017). His photo was published 14 September by Nunatsiaq News.

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Wrangel Island research team counted a record number of Chukchi Sea polar bears in 2020

Many Chukchi Sea polar bears spend the summer on Wrangel Island and a survey there conducted by Russian researchers in 2020 reportedly collected data on a record 747 bears, well up from the 589 reportedly counted in 2017 by the same team (photo below is from 2015).

Note the latest survey of the Chukchi Sea estimated about 3,000 bears inhabit the region (AC SWG 2018; Regehr et al. 2018), at least 1,000 more that the figure of 2,000 used in recent IUCN assessments and survival predictions (Amstrup et al. 2007; Regehr et al. 2016; Wiig et al. 2015). Wrangel Island is the primary terrestrial denning area in the Chukchi Sea (Garner et al. 1984; Rode et al. 2014) and a recently published study showed that the body condition (i.e. fatness) and litter size of Chukchi Sea polar bears has not been negatively affected by low summer sea ice (Rode et al. 2021).

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Still waiting for two thirds of polar bears worldwide to disappear due to lack of summer sea ice

It’s hard to believe that a polar bear specialist would claim that their predictions have come true, given the facts of the matter: that polar bears arguably number over 30,000 worldwide and regions with the most dramatic sea ice declines have not documented reduced polar bear health or survival. But in mid-July this year, Andrew Derocher – one of the field’s most vocal promoters – did just that: proclaimed on twitter that “virtually all of our predictions are coming true.” Except, none of them did, especially the most widely-promoted one, which failed spectacularly.

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Svalbard polar bear paper falsely assumes that loss of genetic diversity has negative consequences

A new paper published today deals with an animal conservation issue I’ve addressed twice before: the theoretical assumption that loss of genetic diversity must be detrimental to species survival despite there being little evidence that this has been the case in real life. For this new study, the authors carried out some complicated measuring of genetic diversity loss and inbreeding amongst and between Svalbard region polar bear populations between 1995 and 2016 (see map below), and then modelled what this could lead to in 100 generations (1210 years), with the over-anxious hand-wringing we’ve all come to expect from such prophesies. As far as I can see, it’s all meaningless number-crunching without relevance to the real world of polar bears.

To support their claim of harm from loss of genetic diversity, the authors of this paper (Maduna et al. 2021) cite four theoretical papers that assume as fact that loss of genetic diversity is harmful but not the evidence to back up the claim. They apparently never bothered to look at species that have actually suffered dramatic loss of genetic diversity. Northern elephant seals, for example, reduced to 20-30 animals more than 100 years ago, have rebounded to a population of about 170,000 with extremely low genetic diversity but no apparent health or survival repercussions. Similar genetic bottlenecks and recoveries have been documented in Guadalupe fur seals, San Nicolas Island foxes, mouflon sheep, and North Atlantic right whales (among others), which I discussed in detail here (with references). I discussed the issue again in regards to a similar polar bear ‘genetic diversity’ paper in 2016.

Conspicuous by its absence in this new publication is a citation of the recent paper that revealed the body condition of female Svalbard polar bears had increased significantly between 2004 and 2017 despite a pronounced decline in summer and winter sea ice extent (Lippold et al. 2019: 988). Nor did the paper cite data collected by the Norwegian Polar Institute that show the body condition of adult males in Svalbard has not changed since 1993 or that population numbers have not declined. Instead, the authors mention only that reduced numbers of pregnant females have reached traditional denning areas due to lack of ice and that bears have spent less time feeding at glacier fronts than they used to do (Maduna et al. 2021: 2), as if the only polar bear data available in relation to sea ice decline was negative.

Figure 1 from Maduna et al. 2021

Population bottlenecks during the Last Glacial Maximum when suitable habitat was scarce and another in the late 1800s/early 1900s due to wanton overhunting left polar bears with remarkably low genetic diversity but no apparent ill-effects to their overall heath. Oddly, this recent work by Maduna and colleagues assumes without evidence that a bit less genetic diversity could be devastating to Svalbard bears more than 1000 years from now. While the media expectedly promote this as scary new evidence of what climate change has wrought (here and here), I am not impressed.

This is conservation biology done WWF-style: loss of genetic diversity sounds bad to people who don’t know better, but real-world evidence shows it isn’t.

References

Lippold, A., Bourgeon, S., Aars, J., Andersen, M., Polder, A., Lyche, J.L., Bytingsvik, J., Jenssen, B.M., Derocher, A.E., Welker, J.M. and Routti, H. 2019. Temporal trends of persistent organic pollutants in Barents Sea polar bears (Ursus maritimus) in relation to changes in feeding habits and body condition. Environmental Science and Technology 53(2):984-995. https://pubs.acs.org/doi/10.1021/acs.est.8b05416

Maduna, S. N., Aars, J., Fløystad, I., Klütsch, C. F. C., Zeyl Fiskebeck, E. M. L., Wiig, Ø. et al. 2021. Sea ice reduction drives genetic differentiation among Barents Sea polar bears. Proceedings of the Royals Society B  288 (1958): 20211741. https://doi.org/10.1098/rspb.2021.1741 OPEN ACCESS

Abundant Chukchi Sea ice explains silence on walrus haulouts in Alaska and Russia so far

There has been abundant sea ice in the Chukchi Sea this summer: so much so that walrus herds have not found it necessary to use beaches on the Alaskan coast as resting haulouts. Now, in early September, almost the entire northern Chukotka coast is covered in ice, blocking use of those beaches that have been traditionally used in September through November. Wrangel Island (an important denning area for polar bears) is still almost surrounded by ice, which hasn’t happened in decades.

Just two years ago, a big deal was made of the fact that the entire coast of Alaska was ice-free by early August and that walrus herds had come ashore at Point Lay earlier than any year since 2007 – all put down to climate change. Last year, walrus started to come ashore one day earlier than in 2019, on July 29. Although no one has presented any evidence that the walrus are suffering in any way due to using beach haulouts during the ice-free season (MacCracken et al. 2017), the haulouts are still presented as bad news and portends of catastrophe to come.

Inset map above shows the location of Point Lay, Alaska where Pacific walrus haulout during the ice-free season.

This year is a totally different story and of course, the biologists are suddenly silent.

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My new science book for kids Walrus Facts & Myths is available now!

I am thrilled announce that my new science book for kids, Walrus Facts & Myths is now available for sale on Amazon. This unique book fills an enormous need.

Thanks to media reports and television documentaries – here’s looking at you David Attenborough – many children around the world have been led to believe that walrus are dying in large numbers every year because of reduced sea ice. This has left kids feeling despondent and powerless. The relentless messaging that walrus are doomed (and that it’s all the fault of humans burning fossil fuels) is fortunately false. It’s time the children learned the truth and now, there’s a book for that!

This is a walrus science book for kids with lots of great photos and a format that readers of all ages will enjoy.

In the US, find it here and in Canada here.

In the UK, find it here. And if you want to know more, there is a review by Kip Hansen posted at WUWT.

My nonfiction book for adults Fallen Icon: David Attenborough and the Walrus Deception, will be released in a few weeks but here is a science book just for the kids. If the children in your life enjoyed Polar Bear Facts & Myths, I’m sure they’ll love this one too. The colour photos are beautiful and engaging. It’s also perfect for homeschoolers wanting to learn about Arctic ecology and walrus life history.

Walrus Facts & Myths is available in paperback and ebook formats.