This is the second year in a row that freeze-up of Western Hudson Bay ice has come earlier than average. Movement of tagged bears and reports by folks on the ground in WH show some polar bears are starting to hunt seals on the sea ice that’s developing along the shore. It’s unlikely that a strong wind will again blow the newly-formed ice offshore (as happened earlier this year) because the ice is more extensive. It seems polar bear viewing season in Churchill will be ending early this year, just like it did last year.
The 9 November map Andrew Derocher (University of Albera) published on twitter showing tagged and collared polar bear movements on Hudson Bay makes it look like almost no ice is present:
However, the Canadian Ice Service chart for 10 November shows the ice very clearly:
UPDATE 13 November 2018: See more recent ice charts and the latest (November 4-11, week 19) report from the Polar Bear Alert Program in Churchill that confirms the bears are moving offshore.
Posted in Conservation Status, Life History, Sea ice habitat
Tagged alert, charts, Churchill, concentration, freeze-up, Hudson Bay, hunting, polar bear, problem bears, sea ice, seals
Ryrkaypiy on the Chukotka coast of Russia is similar to Churchill, Manitoba: both human settlements are of similar size and are close to where polar bears wait for sea ice to form in the fall and where some pregnant females make their maternity dens in preparation for the birth of cubs over the winter (Durner et al. 2018:xxii). Sea ice advances from the west along the Chukotka shore and bears cannot move offshore to resume hunting until the sea ice reaches the village of Ryrkaypiy. According to the Siberian Times, the village is again having problems with local polar bears, as they have for the last several years (including 2013).
“At least twelve polar bears are inside the village, with some of them paying daily visits.
The rest are within three kilometres away.
‘We have to constantly scare the bears away with signal rockets, so far thanks to efforts of the Bear Patrol we manage well’, said acting head of Ryrkaypiy Yevgenia Malakhova.
The large group of bears started to form a month ago when they came close to Cape Kozhevnikov.
‘Now the bears moved close to the village, they also walk back and forth all along the shore line. The animals are irritated because they are ready to leave the area and start hunting in the deep sea, but ice is too thin’, said Malakhova.
All 760 locals are aware of the dangerous situation and take extreme care when moving around the place.”
More below, including map and ice chart.
Posted in Life History, Polar bear attacks, Sea ice habitat
Tagged attractants, carcasses, Chukchi Sea, Chukotka, Churchill, polar bear, problem bears, Russian, sea ice, Wrangel Island
What a difference two weeks make! When the seasonal minimum Arctic sea ice extent occurs in September, polar bear doom-mongers always forget to tell you that within two months, sea ice will return to virtually all regions where polar bears have spent the summer on land, including Hudson Bay. Just as it did in 2007, when polar bears did not die by the thousands due to lack of fall sea ice, polar bear habitat is reforming.
This year, the seasonal minimum came on 23 September. Despite the fact that the US National Snow and Ice Data Center proclaimed that “unusual warmth” in the Arctic continued during October, over the last two weeks sea ice expanded from 6 mkm2 to 9 mkm2. At the current rate of ice growth documented by sea ice charts (see below), Arctic sea ice will be wide-spread by 23 November.
Churchill, Manitoba is proud of its management of problem polar bears and rightly so. But it took time and money to implement the solutions that allowed Churchill to function as it does today, and that should be a lesson for other Arctic communities that have only really started to have problems with polar bears in recent years.
For those who want to understand the problems facing other communities, including Arviat (formerly “Eskimo Point”), a town 260 km north of Churchill. Arviat has a population more than three times the size of Churchill and has been having significant problems with bears since about 2007. I’ve made an excerpt of an excellent paper written by Ian Stirling and colleagues that was published back in 1977 (Stirling et al. 1977).
It describes in detail the problems Churchill had with polar bears in the 1960s and 70s when bear numbers were on the rise — and the various steps that were taken to try and resolve them (even by the time the paper was written, not all of them had been adequately resolved, see Kearney 1989). It’s a fascinating read — see it here.
What’s a good analogy for sea ice as essential polar bear habitat? Biologist Andrew Derocher claims that the soil in a forest is appropriate, because without the soil you can’t have the forest ecosystem. However, that’s a specious comparison because the amount of soil in a forest does not change markedly with the seasons the way that Arctic sea ice does.
A much better analogy is a big pond that dries up a bit every summer. The amount of habitat available to sustain aquatic plants, amphibians and insects is reduced in the dry season but many species have special adaptations for surviving reduced water availability. For the rest of the year, however, the pond provides an abundant and non-limiting habitat for all the creatures and plants that live there.
Posted in Advocacy, Life History, Sea ice habitat
Tagged analogy, ecosystem, extinction, forest, habitat, Interglacials, polar bears, resilience, sea ice, wetlands
Last year, an early freeze-up of Western Hudson Bay sea ice almost ruined the Polar Bear Week campaign devised by Polar Bears International to drum up donation dollars and public sympathy for polar bear conservation. Many bears were on the ice hunting by 7-8 November in 2017 before the celebratory week was done (the average date that bears left the ice in the 1980s): sea ice charts suggest the same may be happening this year.
Ice is forming along the Hudson Bay coast more than a week earlier than it was last year (barely discernible on the map below but detailed ice charts show it clearly), consistent with early build-up of ice in the Canadian Archipelago, East Greenland, and Foxe Basin since mid-September.
The question is: will the ice continue to build over the next few weeks or get blown offshore? See the ice charts below for this year and 2017.
Posted in Life History, Sea ice habitat
Tagged Churchill, freeze-up, gray ice, Hudson Bay, new ice, polar bear alert, polar bears, sea ice, shorefast ice, western hudson bay, winds
A recent study by Norwegian biologist Karen Lone and colleagues, who tagged 57 polar bear females with sensors around Svalbard, discovered that polar bears can dive to a maximum depth of 13.9m and can swim long distances across open water without rest. Contrary to previous claims, polar bears are excellent divers and their breath-holding ability did not seem to limit how deep they could dive.
From the abstract of the new paper by Lone and colleagues (Lone et al. 2018):
“Some bears undertook notable long-distance-swims. Dive depths up to 13.9 m were recorded, with dives ≥5 m being common. The considerable swimming and diving capacities of polar bears might provide them with tools to exploit aquatic environments previously not utilized.”
Compare the above statement to one made by Stirling and van Meurs (2015), after describing a 3 minute dive video-taped during an aquatic stalk of a bearded seal, also in the Svalbard area:
“…increased diving ability cannot evolve rapidly enough to compensate for the increasing difficulty of hunting seals because of the rapidly declining availability of sea ice during the open-water period resulting from climate warming.” [my bold]
These two papers really show the difference between using anecdotal accounts as if they were evidence of species-wide physical abilities and doing a scientific study on the physical ability of interest.
Posted in Advocacy, Life History, Sea ice habitat
Tagged continuous swims, depth, dive, harbour seals, polar bear, Spitsbergen, stalk, Stirling, Svalbard, swimming, underwater