Svalbard is still ice-free this fall, which it has been rather consistently for at least ten years but the amount of sea ice greater than ‘normal’ in the Eastern Canadian Arctic at this date is something to behold. Yet contrary to predictions, polar bears in Svalbard are thriving.
Comments Off on Eastern Canadian Arctic has much more sea ice than usual while Svalbard polar bears deal with less
Posted in Life History, Sea ice habitat
Tagged baffin bay, Barents Sea, Davis Strait, Franz Josef Land, freeze-up, Hudson Bay, polar bear, sea ice, Svalbard, western hudson bay
Last week (24 February 2021), The Guardian was promoting a study that claims polar bears now use four times more energy than expected to survive because of ‘major ice loss’ in the Arctic, as a way of suggesting that the animals are already on their way to extinction.
But like many papers of this type, this study by Anthony Pagano and Terri Williams (Pagano and Williams 2021) is yet another model describing what biologists think may be happening based on experimental data collected from individual bears, not a conclusion based on evidence collected from subpopulations with the worst amounts of ice loss.
Comments Off on More polar bear catastrophe hype: bears use four times more energy than expected
Posted in Advocacy, Conservation Status, Life History, Sea ice habitat
Tagged baffin bay, Barents Sea, Chukchi Sea, contraditions, energy, experimental evidence, habitat loss, polar bear, real world evidence, sea ice
An article by CBC News today (3 March 2020) is a surprisingly well-balance report on a recently published paper by Kristin Laidre and colleagues on their work on Baffin Bay polar bears that I discussed last month. It presents the Inuit perspective that polar bears are currently abundant in the area and the population stable despite less summer sea ice and some documented declines in body weight and at least one scientist conceded this is indeed true.
Fat polar bear, summer 2012 near Thule, NW Greenland (Baffin Bay subpopulation). Robin Davies photo.
However, the CBC writer still left out the most critical caveat included in the paper about the study: that factors other than changes in sea ice could have affected the body condition and litter size data that the authors documented but they didn’t look at anything except sea ice. This automatically means the conclusions are scientifically inconclusive.
See some quotes below from the CBC article and the caveat from the paper. Continue reading
Comments Off on Baffin Bay polar bears are abundant and the population is stable, study scientist admits
Posted in Conservation Status, Population, Sea ice habitat
Tagged abundant, baffin bay, body condition, causation, caveat, correlation, polar bear, population size, sea ice, stable
A new paper on Baffin Bay polar bears reports data on body condition and litter sizes collected as part of a major study of the region completed in 2013 compared to sea ice declines since the 1990s; based on a computer model, the authors predict that in 37 years time (if sea ice declines continuously), the incidence of twin litters could “largely disappear.” However, no decline in population numbers was predicted and a critical caveat acknowledges that factors other than changes in sea ice could have affected the body condition and litter size data the authors analyzed, which means the conclusions are scientifically inconclusive.
Fat polar bear, summer 2012 near Thule, NW Greenland (Baffin Bay subpopulation). Robin Davies photo.
The last (2013) polar bear population survey of Baffin Bay (SWG 2016) generated an estimate of almost 3,000 (2,826; range 2,059-3,593), which means that regardless of some slight changes in body condition and litter size over the last two decades (which may or may not have been caused by loss of sea ice), there are currently a lot of bears in Baffin Bay.
Comments Off on New paper says Baffin Bay polar bears may have been affected by less summer sea ice
Posted in Conservation Status, Life History, Sea ice habitat
Tagged baffin bay, body condition, causation, correlation, extinction, fatness, Greenland, litter size, NASA, polar bear, sea ice, weight
Large margins of error in polar bear population estimates means the conservation status threshold of a 30% decline (real or predicted) used by the US Endangered Species Act and the IUCN Red List is probably not valid for this species.
Several recent subpopulation estimates have shown an increase between one estimate and another of greater than 30% yet deemed not to be statistically significant due to large margins of error. How can such estimates be used to assess whether population numbers have declined enough to warrant IUCN Red List or ESA protection?
What do polar bear population numbers mean for conservation status, if anything?
Comments Off on Polar bear numbers, margins of error, & consequences for conservation status
Posted in Conservation Status, Population
Tagged baffin bay, declining, Derocher, errors, ESA, estimate, facts, IUCN Red List, numbers, polar bear, population, science, significance, statistics, Svalbard, western hudson bay
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.
Comments Off on Breakup of sea ice on track in Canada as critical feeding period for polar bears ends
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
The 2016 Scientific Working Group report on Baffin Bay and Kane Basin polar bears was released online without fanfare last week, confirming what local Inuit have been saying for years: contrary to the assertions of Polar Bear Specialist Group scientists, Baffin Bay and Kane Basin subpopulations have not been declining but are stable.
Until recently, the Baffin Bay (BB) and Kane Basin (KB) polar bear subpopulations, that live between NW Greenland, and Baffin and Ellesmere Islands, were assessed with confidence by the IUCN Polar Bear Specialist Group (PBSG) to be declining due to suspected over-hunting (see 2016 Report, Ch. 1, pg. 4).
It turns out they were wrong.
Baffin Bay – 2,826 (95% CI = 2,059-3,593) at 2013
[vs. 1546 (95% CI = 690-2,402) expected 2004]
vs. 2,074 (95% CI = 1,553-2,595) in 1997
Kane Basin – 357 (95% CI: 221 – 493) at 2013
vs. 164 (95% CI: 94 – 234) in 1997
[1997 figures from 2015 IUCN Red List estimates, from Supplement, pg. 8); 2004 “expected” figure for Baffin Bay from 2016 SWG report, Ch. 1, pg. 4]
In 2014, Environment Canada’s assessments were ‘data deficient’ for Kane Basin and ‘likely declining’ for Baffin Bay (see map below):
However, the results of this new study (conducted 2011-2013) would likely make KB in the map above dark blue (‘stable’), and BB light blue (‘likely stable’), depending on how the new information is interpreted (given differences in methodology between the 1991-1997 and 2011-2013 counts). Note that a recent paper by Jordan York, Mitch Taylor and others (York et al. 2016) suggested this outcome for Baffin Bay was likely (i.e. ‘stable’) but thought that the status of Kane Basin would remain ‘declining.’
This new information leaves only the Southern Beaufort subpopulation (SB) in a ‘likely declining’ condition, but since that decline was due to thick spring ice conditions in 2004-2006 (Crockford 2017), it does not reflect a response to recent loss of summer sea ice. The new population estimates for Baffin Bay and Kane Basin also suggests that a revision needs to be made to the 2015 IUCN Red List assessment with respect to the global population estimate because polar bears are clearly more abundant in Baffin Bay and Kane Basin than previously thought.
Comments Off on Baffin Bay and Kane Basin polar bears not ‘declining’ concludes new report
Posted in Conservation Status, Population, Sea ice habitat
Tagged abundance, baffin bay, declining, genetic mark-recapture, Kane Basin, overhunting, PGSG, polar bear, population size, Red list, stable, TEK, trends
A part-time Arctic researcher eager for media attention suggested earlier today that the ice entrapment of narwhals in 2008 and again in 2015 at Pond Inlet (that made headlines around the world) was the result of “sudden changes in temperature” caused by climate change. This grossly misleading claim ignores the facts: ice entrapment of narwhals is an entirely natural feature of the Arctic that has been known about for hundreds of years.
“Narwhals: the ‘giant unicorn of the sea’ at risk from climate change” (CBC, 13 August 2016), a print version of a CBC Radio interview with Clint Wright that aired 8 August 2016. Wright is the general manager at the Vancouver Aquarium and apparently has “joined a team of researchers to tag and study” narwhals for several years – but does not seem to know much about the history or circumstances of natural ice entrapment.
Ice entrapment of small whales is nothing new. The first formally documented incident – in English – occurred in 1915 (Porsild 1918) and the phenomenon has probably occurred as long as there has been ice in the Arctic (millions of years).
Animals routinely become trapped in a few specific areas due to local geography: when ice that forms in the north moves south quickly, it blocks the entrances to inlets or coastal bays that still have open water. The presence of the pack ice causes nearby temperatures to drop quickly. Rapid development of ice on the bay proceeds from the mouth toward the head of the bay. Any whales present cannot escape to open water and will eventually die or be eaten.
Pond Inlet at the north end of Baffin Island is one such place but Disko Bay in western Greenland is another. In fact, Pond Inlet and Disko Bay are almost identical in geographic layout even though they lie on opposite sides of Baffin Bay, so it’s not surprising that both are locations of repeated entrapment events.
Three highly informative journal articles on the phenomenon of ice entrapment of narwhals and beluga are open access documents that reveal some fascinating details of such incidents, including polar bear predation on trapped whales. h/t T. Nelson Continue reading
Comments Off on Narwhal and beluga ice entrapment is natural – not caused by global warming
Posted in History, Life History, Sea ice habitat, Uncategorized
Tagged Arctic, baffin bay, beluga, climate, climate change, Clint Wright, Disko Bay, entrapment, facts, global warming, narwhal, polar bear, Pond Inlet, predation, prey, risk, sea ice, threatened, trapped, unicorn, Vancouver Aquarium, weather, whales
National Geographic has just posted an exclusive video shot mid-summer of 2015 of a male polar bear killing and eating a young cub.
It’s worth watching (23 February 2016; “Polar bear cannialzies cub“) [update: Youtube version posted below]. It was filmed in 2015 in Baffin Bay at mid-summer (during either their July 28-Aug 9 or Aug 7- 19 cruise; pdf of itinerary, dates and prices – oh my god, the prices! here). [Summer is 1 July-30 September]
You’ll soon realize the male bear was not thin or starving (as was true of a much-publicized 2011 event captured on film off Svalbard).
It is also obvious based on the dates listed above that this incident debunks the explanation that cannibalism by adult males is driven primarily by their desire to mate with the mother of the consumed cub: this incident occurred sometime between August 7 and August 19 (as I was informed via email, by a reader on one of those two cruises), which is well past the breeding season for polar bears. A male bear would not still have viable sperm by August and a female could not be forced into estrus. [added 26 February 2016]
National Geographic is already hyping this incident as more evidence of climate change harming polar bears, as the article accompanying the video suggests. However, this is just the typical oversell that accompanies much to do with polar bear these days.
The bear was not “driven to desperation” : he simply took advantage of a rare chance to eat during the summer:
“Without the ability to hunt seals, polar bears may be driven to ever more extreme cannibalism, if they’re not already.”
It’s clear to me that this was an opportunistic kill made at a time of year when few seals are available, as even Stirling admits. It reiterates the point I’ve made many times before, that polar bears on the sea ice in summer have few feeding opportunities.
Incidents of cannibalism cannot be said to be increasing because there is no scientific baseline for which recent occurrences can be compared. Scattered anecdotal reports of any behaviour cannot be touted as evidence for a trend even though they may be of interest and worth recording.
UPDATE 23 February 2016: Video now posted on Youtube, see it copied below:
Comments Off on Cannibalism video shot in 2015 did not involve a starving polar bear
Posted in Cannibalism, Life History
Tagged baffin bay, cannibalism, climate change, desperation, facts, National Geographic, polar bear, starving
Fall is the season when polar bears that have spent the summer fasting can return to the refreezing sea ice to resume successful hunting. For polar bears, fall is the second-most important time of year for hunting, after spring.
The date when freeze-up occurs across the Arctic varies from place to place and year to year, but the process is well underway this year. The US National Snow and Ice Data Center’s MASIE map for 20 October 2015 (above) shows 7.7 mkm2 of sea ice, up from the annual low of 4.41 mkm2 almost 6 weeks ago.
Comments Off on Winter returns to the Arctic – freeze-up 2015 at October 20 expands polar bear habitat
Posted in Sea ice habitat
Tagged baffin bay, Barents Sea, Beaufort Sea, Foxe Basin, freeze-up, habitat, polar bear, sea ice
You must be logged in to post a comment.