polarbearscience | Polar bear science past and present

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Posted on February 26, 2020 | Comments Off on Global polar bear abundance best guess estimate is 39,000(26,000-58,000) This is a sticky post link to my March 2019 essay on polar bear numbers at 2018. View it here. Comments Off on Global polar bear abundance best guess estimate is 39,000(26,000-58,000) Posted in Population Posted on December 22, 2020 | Comments Off on Late fall polar bear habitat 2020 compared to some previousyearsIt s time to look at sea ice habitat at 15 December (Julian Day 350), now that virtually all bears except pregnant females throughout the Arctic are either out on the sea ice attempting to hunt for seals or hunkered down against the darkness.As is usual at this time of year, the Canadian Archipelago, the Beaufort, East Siberian and Laptev Seas are well covered in ice (see regions on map below). As for the rest, despite what one polar bear specialist has implied there is no evidence that a slower-than-usual fall freeze-up in the other peripheral seas of the Arctic negatively affects polar bear health or survival.In fact, because of the attractiveness of the ice edge for seals in the fall, as I discussed last month, it s possible that the longer the ice edge persists in fall, the more successful polar bears will be in hunting seals – except those above the Arctic Circle where lack of daylight from early November may cause polar bears to hunker down and rest rather than try to hunt through the darkness. But we ll never know for sure, because bears have never been studied at this time of year – experts simply make assumptions about what happens (e.g. Stirling and Oritsland 1995).Sea ice thickness also varies year to year throughout the season but does not matter much to polar bears, who hunt most successfully in first year ice less than 2m in thickness, which comprises all of the regions currently purple in the ice thickness chart below.Hudson BayThis year at mid-December, there was more ice than usual in central and southern Hudson Bay (below) and somewhat less than usual in the eastern portion.However, the ice is forming so fast now that by 18 December there was hardly any open water remaing over Hudson Bay and the ice to the north was solidifying (below). Recall that a similar freeze-up pattern left a pod of a dozen or so killer whales stranded in mid-January 2013 and killed four others in 2016. Such ice-entrapment suggests that despite a warming Arctic, freeze-up patterns would have to change very dramatically for Hudson Bay to be an attractive place for killer whales. A recent DFO report concluded:Killer whale ice entrapments are almost always fatal and can wipe out entire family groups, with long-lasting demographic impacts. Ice entrapments could therefore slow Arctic killer whale range expansions, particularly in areas where killer whales that are unfamiliar with sea-ice patterns fail to exit prior to ice formation in winter.Compare Hudson Bay weekly stage of development charts (below) for this year back to 2014, from the Canadian Ice Service archives. You ll see that this year appears to have more extensive 1st year ice (light green, ca. 30-70 cm) than any other year (although last year had almost as much) and that 2016 was notable as being a very late freeze-up year:Western Hudson Bay polar bears with collars or tags deployed by Andrew Derocher and his University of Alberta crew (below) are spread out over the ice of the bay (two on land are denning females), a number are on the thickest ice in the north but others are on thinner ice to the south and east:Baffin Bay, foxe basin, and Davis StraitIce covereage in the Canadian Eastern Arctic at mid-December is about average this year, according to CIS charts – only a bit of red and pink indicating below normal in the east (off of Greenland): Pack ice has moved down from the north through Baffin Bay into Davis Strait (below) and will soon be off the coast of Labrador, which has somewhat less ice than usual this year at mid-December:The ice off Labrador at this time is shorefast ice developing and thickening in place (below). As far as we know, few polar bears summer on the northern Labrador coast, so this late ice development is unlikely to affect local bears. However, pack ice will move down during January and February until it engulfs the area north of Newfoundland, bringing some polar bears with it.Greenland and Barents SeaFreeze-up in the Greenland Sea is progressing a bit faster than usual for the last five years (below), but not remarkably so:Ice cover in the Barents Sea (below) has been slow so far but has been progressing faster over the last few weeks. There is now ice off the east coast of Novaya Zemlya, shorefast ice that should allow any bears summering there to hunt for seals just as Western Hudson Bay bears do during early freeze-up stages. Within the next few weeks, the Arctic pack ice will move south into the Kara Sea, allowing bears to move more freely.Ice off Svalbard has been much below normal (below), as it has been for years now, which is why virtually all Barents Sea pregnant females currently make maternity dens in Franz Josef Land or on the sea ice to the north. These alternative areas for safely giving birth is the primary reason that the much reduced sea ice around Svalbard in recent years has not impacted Barents Sea polar bear health or survival.Kara SeaIce cover in the Kara Sea at 15 December (below) is lower compared to the last five years but it s unclear how much effect this will have on local polar bears.Animals that have opted to spend the ice-free season on Novaya Zemlya or on the Russian mainland will have had a long wait for ice, but those that spent the summer on the Severnya Zemlya archipelago to the east had access to sea ice before the end of November. There has been no word from Belushaya Guba on whether the polar bear problems they had because of poorly maintained garbage dumps in December 2018 that went on until February 2019 have recurred this year.Despite what Andrew Derocher claims (below), there is no evidence that slightly less sea ice in the fall is detrimental to polar bear health or survival in the Kara Sea or elsewhere. It is possible that it might but no one has studied it, so to suggest that low sea ice cover is trouble for polar bears at this time of year is very misleading.High temperatures = low sea ice cover trouble for polar bears. We know little about the Kara Sea polar bears but we have many studies showing negative effects of warming on polar bears in other areas. The problems all start with declining sea ice. pic.twitter.com/qlFilxrtHm Andrew Derocher (@AEDerocher) December 14, 2020Chukchi/Bering SeaSea ice cover over the Chukchi Sea is a bit lower than it has been over the last few years, about as low as it was in 2017 (below).Chukchi Sea polar bears at 14 December (below) had abundant sea ice habitat.In 2016, when Chukchi polar bears were counted for the first time, there was a similar amount of ice at this time of year (below):ReferencesStirling, I. and Øritsland, N. A. 1995. Relationships between estimates of ringed seal (Phoca hispida) and polar bear (Ursus maritimus) populations in the Canadian Arctic. Canadian Journal of Fisheries and Aquatic Sciences 52: 2594 – 2612. http://www.nrcresearchpress.com/doi/abs/10.1139/f95-849#.VNep0y5v_gU Posted on December 20, 2020 | Comments Off on Polar bears again attracted to Russian town by dead walrus Attenborough blames on no seaice In the news again: Cape Schmidt (on the Chukchi Sea) made famous by Sir David Attenborough s false claim that walrus fell to their deaths because of lack of sea ice due to climate change when a clever polar bear hunting strategy was actually to blame.Ryrkaypiy overrun by polar bears Dec 2019 WWF photoLast year in December (above), some bears were feeding at Ryrkaypiy s garbage dump and wandering around town after being displaced from feeding on walrus carcasses by bigger, stronger bears on the nearby point.This year, the town has managed to keep the bears out of town, so while the residents are having no real problems, more than 30 bears have been spotted near town, almost certainly feeding on natural-death carcasses of walrus along the shore (see photo below from 2017 where Ryrkaypiy can be seen in the background). Continue reading Posted on December 17, 2020 | Comments Off on The conundrum of Hudson Bay bears that left shore late in 1983 with video from CBCarchives In 1983, it was claimed that freeze-up of Hudson Bay was so late that polar bears didn t leave the shore until the 4th of December – several weeks later than had been usual at that time. However, the fact that sea ice charts show significant ice offshore weeks before that time suggests something else was probably going on.About three weeks ago, CBC News republished an article (with video) from their 1983 archives for 1 December, about the plight of the people of Churchill who had already suffered one death and one serious mauling by polar bears. That was thirty-seven years ago, long before lack of sea ice was blamed for everything bad that happened to Western Hudson Bay polar bears. In fact, rather than a really late freeze-up, it appears the problem had more to do with the fact the bears had had an especially tough spring that year and arrived onshore in only OK condition – and as a consequence, the town dump became such a strong attractant for many bears that they were reluctant to leave when the sea ice formed offshore. Continue reading Posted on December 10, 2020 | Comments Off on Raise your hand if you knew Newfoundland was devastated by a major tsunami in1929 Posted on December 6, 2020 | Comments Off on Speculation on ice-trapped whales: science-based fiction vs. dishonestscienceIce entrapment of whales is known to happen across the Arctic, including Davis Strait and the Gulf of St. Lawrence. How common such phenomena were in the past or might be in the future are subjects of conjecture. However, while speculation is the bread-and-butter of science-based fiction, it is the bane of peer-reviewed science. I ve written two novels informed by science set a bit in the future (2025-2026) in Eastern Canada: EATEN was set in Newfoundland and my latest book UPHEAVAL –see a review here – is set in Cape Breton Island, Nova Scotia. In UPHEAVAL, one of the issues I explore is ice entrapment of large whales, like North Atlantic right whales. I speculate in the story whether carcasses of ice-killed whales might provide a powerful enough attraction to lure Davis Strait polar bears down from Labrador and the Strait of Belle Isle into the Gulf of St. Lawrence – and if they did, what might be the repercussions of that shift in distribution.Here I argue that a novel is the appropriate place for this kind of speculation and researchers who offer such conjecture to the public in a way that conflates a science-informed guess with evidence-based fact risks eroding public trust in science. Continue reading My new short novel is out! UPHEAVAL is a future disaster thriller about an ice tsunami that devastates Nova Scotia on the Canadian east coast in 2026. And yes, there are polar bears. It s a follow-up to my 2015 novel EATEN but with a completely different focus! Sea ice formation is ahead of usual in some regions and behind in others but overall, sea ice habitat is abundant enough for this time of year for virtually all polar bears across the Arctic to be back out on the sea ice hunting seals.Overall, there was more sea ice at 24 November 2020 than there was on the same date in 2016, which was the last year that a number of polar bear subpopulations were surveyed, including Western and Southern Hudson Bay, Southern Beaufort, Chukchi Sea (Crockford 2019, 2020), see graph below from NSIDC Masie:Northern Hemisphere sea ice at 24 November, 2016-2020.UPDATE 27 November 2020: Problem bear report published today (for week 13, Nov. 16-22) has been added below. Continue readingMy new short novel is set to be published within the next week, in time for Christmas orders. UPHEAVAL is a future disaster thriller about an ice tsunami that devastates Nova Scotia on the Canadian east coast in 2026. And yes, there are polar bears. It s a follow-up to my 2016 novel EATEN but with a slightly different focus! It will be available in paperback and ebook formats. Enter your email address to follow this blog and receive notifications of new posts by email. Join 5,259 other followers Email Address:

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