No extirpation looms for Svalbard polar bears: no pending catastrophe in Norway

Despite a wild claim that a “slow Arctic freeze” this year increases the risk that polar bears will become extinct, sea ice charts show ice returning earlier than it has for decades everywhere except the Svalbard area of the Barents Sea. That’s good news for pregnant polar bears. Although Svalbard is without ice, that’s been true for so many years that pregnant Svalbard females long ago abandoned the use of islands they used in good ice years and now make their dens in the Franz Josef Land archipelago to the east (which is still within the Barents Sea subpopulation region).

Svalbard polar bear fall 2015_Aars

Polar bears give birth around 25 December each year, so pregnant females prefer to be snug in a safe den by around the end of November at the latest. That’s been possible for all regions of the Arctic this year, including the Barents Sea — because sea ice returned to Franz Josef Land weeks ago, even though Svalbard is still ice-free.

Franz_Josef_Land_location_wikipedia

Major denning areas in Russia, including Wrangel Island, have been surrounded by ice since the middle of the month, allowing pregnant females that did not remain on shore over the summer to return to make maternity dens. Elsewhere, bears that have been confined to shore over the ice-free season (such as along Hudson Bay and Baffin Island in eastern Canada) returned to the ice to hunt seals weeks ago after the earliest freeze-up in more than two decades.

Last week, a Guardian newspaper article trumpeted an alarming headline:

SELRES_9a1b24d3-2c02-40c8-a664-751da1a3de15Slow Arctic freeze raises risk of polar bear extinction, say scientistSELRES_9a1b24d3-2c02-40c8-a664-751da1a3de15s: Record absence of ice after freak warm spells denies pregnant bears birthing dens and triggers ‘extirpation event’ warning.” [23 November 2018, The Guardian]

It is unclear from the headline that the article means only Svalbard in the Barents Sea and neglects to inform readers that ice has been late returning in the fall consistently since 2011 and was late several other times before that.

Andrew Derocher, who was the source for the impending “extirpation” suggestion for Svalbard bears (“Polar bears here may be the first extirpation event“), makes it sound like ice conditions this year are a new phenomenon for Svalbard.

Data published by the Norwegian Polar Institute shows low fall ice in 1999-2001, 2004, 2006-2007, 2009-2017.

In 2015 and 2016, no ice at all reached Kong Karls Land (a Svalbard denning area popular in the 1980s) by December 31 and no polar bear dens were found: 2017 had no ice by that date also but no den counts were attempted.

Researcher Jon Aars is quoted in the Guardian article regarding the impact of low fall ice around Svalbard:

“The most immediate concern is for pregnant females, who normally travel across the ice at this time to make maternity dens on Hopen and other islands that are important for reproduction, said Jon Aars of the Norwegian Polar Institute.

“Unless sea ice forms within the next few weeks, pregnant females will have to swim,” he said, noting this uses five times as much energy and runs down fat reserves that are important for producing milk and raising cubs.

Aars said if current climate trends continued bears would struggle, although it was hard to say when the tipping point would be.

“In 2000, we didn’t foresee that Svalbard would be ice-free at this time of the year,” he said. “If this continues, there’ll be a threshold where it will be hard for the bears to reproduce. Things can happen fast. I’m not optimistic about whether the bears will survive. If the sea ice disappears, then so will the bears.”

You will notice that Aars he does not mention that polar bears have not made dens on Hopen since 2008. Polar bears are not going to swim there this year if the ice does not form, because they do not have to den on Hopen Island or any other island in eastern Svalbard. They can den in Franz Josef Land in Russia and safely have their cubs there.

There will be no extirpation event in Svalbard because Svalbard bears have already adjusted to repeated instances of low fall sea ice coverage by shifting their feeding and denning focus a bit further eastward. Franz Josef Land is an official portion of the Barents Sea polar bear subpopulation region (Svalbard is no more an autonomous polar bear region than Churchill: each is part of a larger whole).

Barents Sea polar bears now den around Franz Josef Land in Russia, where there has been enough ice this year for bears to reach the area since mid-month:

masie_all_zoom_4km 2018 Nov 12

Franz Josef Land is a recognized refugium for pregnant Barents Sea polar bears: an area with suitable habitat that gets ice early enough in the fall to allow them to den successfully, even in low-ice years. This is not my opinion but the discovery made by polar bear specialists working in the region (Aars 2015; Aars et al. 2017; Andersen et al 2012).

However, Norwegian and Canadian researchers cannot study polar bears in Franz Josef Land because it is in Russia. They are understandably upset over loosing their study subjects but the movement of “Norwegian” bears to Russia is not a catastrophe: it is a triumph of survival that should have been anticipated.

Current ice conditions:

masie_all_zoom_4km 2018 Nov 27

References

Aars, J. 2015. Research on polar bears at Norwegian Polar Institute. Online seminar (‘webinar”), January 14. pdf here.

Aars, J., Marques,T.A, Lone, K., Anderson, M., Wiig, Ø., Fløystad, I.M.B., Hagen, S.B. and Buckland, S.T. 2017. The number and distribution of polar bears in the western Barents Sea. Polar Research 36:1. 1374125. doi:10.1080/17518369.2017.1374125

Andersen, M., Derocher, A.E., Wiig, O. and Aars, J. 2012. Polar bear (Ursus maritimus) maternity den distribution in Svalbard, Norway. Polar Biology 35:499–508. https://link.springer.com/article/10.1007/s00300-011-1094-y

via polarbearscience

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November 29, 2018 at 03:56AM

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