A Southern Beaufort female with cubs, from the fall of 2007.
Note the non-starving condition.
Twenty-one amazing photos of polar bears feasting on the remains of a bowhead whale carcass outside of Kaktovik, Alaska, taken by wildlife photographer Michal Tyl, have been posted by the UK Daily Mail (December 12, 2013): “Now that’s what you call a spare rib! Pack of bloody-faced polar bears spend day and night stripping a beached whale to its bones.“ Have a look and see if you can spot any “starving” bears!
What you will see is the relative size of the bears: notice how much larger males are than females, how small cubs-of-the-year are relative to big males. Oh, and notice all the big fat polar bear butts. I can’t include any of the photos here because of copyright rules (the one above is from 2007) but I have included a map showing the location of Kaktovik, a quote from the article, and a link to my previous post on Kaktovik bears, which has a wealth of background information. Continue reading
[Update Nov. 23, 2013: I've added a few comments, noted, in the text]
This is a follow-up to an earlier post, Polar bear problems in N Hudson Bay not due to late freeze-up, to counter some misinformation that’s being circulated about the history of Hudson Bay freeze-up dates.
Polar bear biologists working in Western Hudson Bay published new definitions of breakup and freeze-up earlier this year. The new method better reflects how polar bears interact with seasonal changes in sea ice on the bay.
Formerly, 50% ice coverage levels were used to assign the date when major ice change phenomena were reached each year (breakup in summer, freeze-up in fall (e.g. Gagnon and Gough 2005). The new method (Cherry et al. 2013, see discussion here) defines breakup at 30% ice coverage and freeze-up at 10%.
Cherry and colleagues had a fairly complicated method of defining 30% coverage for breakup in Western Hudson Bay. However, freeze-up in the fall is much simpler because ice always forms first along the western shore, starting in the north.
This means that the weekly graphs of ice development provided by the Canadian Ice Service for Hudson Bay, which are expressed as a percentage (just like the Cherry et al. study), can be used to compare freeze-up dates historically.
These graphs refute the absurd claim that freeze-up on Hudson Bay has been “one day later each year” over the last 30 years – an assertion repeated just the other day at PBI. Let’s take a closer look, shall we?
The myth that northern Hudson Bay communities are having problems with polar bears this year because freeze-up is later than usual just won’t go away.
I discussed the well publicized craziness in Churchill last week (here and here), but there’s more. Polar bears are already leaving the shore of Northern Hudson Bay as the ice rapidly forms but I saw a story yesterday (dated late last week) that quoted a local official in Repulse Bay blaming their polar bear problems on late freeze-up.
I’ve written before about the peer-reviewed paper by polar bear researchers Seth Cherry and colleagues published earlier this year on breakup and freeze-up dates between 1991 and 2009. But perhaps the freeze-up data needs more emphasis. I’ve copied that graph again below, with notes, and added some ice maps. See for yourself.
Bottom line: A “late freeze-up” for northwestern Hudson Bay occurs when ice formation is delayed until early December or beyond. Freeze-up was nowhere near “late” this year, nor was the ice “slow to freeze.” It wasn’t last year either.
Posted in Life History, Sea ice habitat
Tagged Arviat, Canadian Ice Service, Foxe Basin, freeze-up, Hudson Bay, human-polar bear conflicts, migration, November ice extent, NSIDC, polar bear problems, polar bears, Repulse Bay
Steven Amstrup, spokesperson for Polar Bears International, has ramped up his “save the polar bear” rhetoric over last week’s nonsense.
Last night (November 13), the NBC News online story (here) that accompanied their evening news clip (h/t DB) included this appalling analogy:
“…Amstrup said greenhouse gases created by humans threaten future generations of bears by threatening their ice. He said he likes to compare climate change’s effect on polar bears to the infamous Titanic ocean liner.
“[It] didn’t matter how many people were on the Titanic or how well they were doing,” he said. “When the Titanic slipped beneath the waves and they lost their habitat, that was it. So polar bears will also go away because of their dependence on sea ice.” [my bold]
Amstrup really wants people to believe that all the polar bears in the world will die some day, all at once, in some mega ice-loss catastrophe!
Here is the October follow-up to my post on the July track map for female polar bears being followed by satellite in the Beaufort Sea by the US Geological Survey (USGS) – Ten out of ten polar bears being tracked this summer in the Beaufort Sea are on the ice. See that post for methods and other background on this topic, and some track maps from 2012 (also available at the USGS website here).
The track map for October is copied below (Figure 1).
By the end of October, ice reached the coast in several areas. The ten bears from July were down to seven – their collars might have stopped working or fallen off (most likely), they might have left the area entirely (also possible) or they might have died (the researchers don’t say which).
Here’s the ground-truth follow-up to my suggestion of what polar bear habitat would likely look like 6 weeks after the minimum extent was reached this year – which was looking then like it would mirror 2009.
You’ll find my discussion, posted on September 22, here. At that point (September 13), ice extent was 5.1 million square kilometers; now it is 9.1 million square kilometers (Fig.1).
Have a look at the maps below: Fig. 2 to see how ice extent at October 31st compares to ice extent at the end of October 2009, and Fig. 3 to see what ice concentrations looked like in the Canadian Arctic.
Posted in Life History, Sea ice habitat
Tagged Beaufort, Canadian Ice Service, Chukchi, Eastern Beaufort, Ferguson, grey-white ice, Hudson Bay, polar bear, sea ice extent, summer ice minimum, young ice
The end of September sea ice summary from the US National Snow and Ice Data Center (NSIDC) finally became available late last week (October 3, “A better year for the cryosphere”).
The summary figure NSIDC provides are the average ice extent for the month (not the maximum achieved at the end of the month), which are compared to previous years.
[There has been considerable ice growth since the end of September (updated daily here].
Here is why the September extent doesn’t matter to polar bears: it is the extent in June that is important to polar bear survival. June is the end of the critical spring feeding period for polar bears (see previous post here) – healthy bears eat more seals over a shorter period of time from March to June than any other time of year. After the end of June, most bears have enough fat to survive a fast of 4 months or more.
In contrast to September – when many bears are taking a time-out on shore – ice extent for June over the last 30 years or so provided an extensive hunting platform for polar bears throughout the Arctic. To show you how extensive, I’ve constructed a composite of ice maps from selected years (Fig.1, below).
Posted in Life History, Sea ice habitat
Tagged Arctic ice extent, average monthly ice extent, hunting platform, June sea ice extent, NSIDC, polar bear survival, polar bears, ring seals, sea ice maps, September ice extent
Here is the follow-up to my post on the July track map for polar bears being followed by satellite in the Beaufort Sea by the US Geological Survey (USGS) – Ten out of ten polar bears being tracked this summer in the Beaufort Sea are on the ice. See that post for methods and other background on this topic, and some track maps from 2012 (also available at the USGS website here).
The track map for September was posted on the USGS website on October 17 (delayed due to the US government shutdown) and is copied here below (Figure 1). The ice rebounded during the second half of the month (after the annual minimum was reached on September 13). The ten bears from July were down to eight – their collars might have stopped working or fallen off (most likely), they might have left the area entirely (also possible) or they might have died (the researchers don’t say which).
Figure 1. Original caption: “Movements of 8 satellite-tagged polar bears for the month of September, 2013. Polar bears were tagged in 2013 on the spring-time sea ice of the southern Beaufort Sea. All 8 of these bears have satellite collar transmitters [i.e., all are females]. Polar bear satellite telemetry data are shown with Ice Analysis charts from 26 August, 2013. Ice Analysis charts are made available by the National Ice Center. The land cover is made available by Natural Earth. Click on the above image to enlarge.” [Note that the dots with the polar bear icons are the end points (end September), while the other end of the string is their position in early September, indicating that the ice is now moving towards the shore. The pink dot present in August is almost entirely obscured by the purple dot, which is overlapping the yellow dot on shore in Alaska; also, the light brown dot is on Banks Island, far right.]
It appears that of the eight polar bears still being followed by USGS researchers in September, four are on shore and four are still on the ice.
Only time will tell if the four females on shore are pregnant and preparing maternity dens for the winter, but this seems the likely reason they are not on the ice with the others.
One very interesting point worth noting:
the one bear (light brown) captured onshore in the Southern Beaufort
subpopulation region in the spring of 2013
, has moved into the Northern Beaufort
subpopulation region, on Banks Island (see map here
), and may be denning there. This inter-subpopulation movement is relatively uncommon.
The map for July 2013 is below, for comparison: Continue reading
Posted in Life History, Sea ice habitat
Tagged Beaufort Sea, denning females, Eastern Beaufort, females with radio collars, habitat, Northern Beaufort, polar bears, sea ice extent, Southern Beaufort, summer ice minimum, summer sea ice, tracking polar bears, tracking polar bears by satellite, USGS
So far, I’ve not discussed the Barents Sea subpopulation in very much detail, except in comparison to other groups. For example, the Barents is considered to be the same type of sea ice “ecoregion” as the Chukchi Sea and the Southern Beaufort (discussed here). Previous studies on the Barents Sea polar bear population (Derocher 2005) indicate it may have recovered from extreme levels of overhunting (discussed here) and had stabilized, or was increasing very slowly, as early as 2002 (discussed here) — similar to what has happened in Davis Strait (discussed here).
Figure 1. Polar bear subpopulations, with the Barents Sea region highlighted; map courtesy the IUCN Polar Bear Specialist Group (PBSG), extra labels added.
The most recent Barents Sea population estimate was done in 2004 (2,650; range ~1900-3600), based on an aerial survey (Aars et al. 2009). Aerial surveys are the only practical method of establishing population counts in regions like this where many bears never set foot on land. The previous estimate for the Barents (1982) was “2,000-5,000” but its accuracy was considered “poor” (discussed here).
The IUCN Polar Bear Specialist Group (PBSG), in their most recent report, lists the Barents Sea population as “data deficient” for status, current trend and estimated risk of decline within 10 years (Obbard et al. 2010:62, Table 1) and the “notes” for this entry say:
“Population estimate is based on a new aerial survey. There was likely an increase in the subpopulation size after 1973 until recently. Current growth trend is unknown.”
This 2004 estimate is now almost a decade old and potentially no longer an accurate representation of what’s happening in the Barents Sea. The most up-to-date information has not yet been published but it is available online. It’s eye-opening to say the least, if only that it appears to be yet another example of a polar bear population that is so far not showing signs of being harmed by sea ice declines, as I’ve discussed before (here).
[Update October 15, 2013: I’ve simplified the text discussion and figure regarding the Aars and Andersen denning study from the original posted]
Posted in Conservation Status, Life History, Population, Sea ice habitat
Tagged aerial survey, Barents Sea, body condition, Derocher, ecoregrions, Environmental Monitoring of Svalbard and Jan Mayen, Jon Aars, litter size, Magnus Andersen, maternity dens, Mauritzen, MOSJ, number of cubs, Olga Pavlova, population size, pregnant females, reproduction, sea ice, Sebastian Gerland, Svalbard
It’s Thanksgiving weekend here in Canada. As a special treat, I thought I’d point you in the direction of a delightful bit of video footage of beluga whales.
If you haven’t seen this Arctic Watch Beluga Foundation clip already, it’s worth a few minutes. It’s footage of belugas and their calves frolicking in the shallow water of Cunningham Inlet, on Somerset Island, Nunavut (within the Lancaster Sound polar bear subpopulation, which is north of the Gulf of Boothia subpopulation region that I discussed previously here and here).
While I previously surmised that Gulf of Boothia polar bears might hunt beluga from remnant ice during the summer in years when the ice doesn’t totally melt (like they do in Hudson Bay, see belugas as food for hungry polar bears), it appears they also successfully hunt beluga in shallow waters like those found in Cunningham Inlet. But there is no hunting footage in this post.
Link and further info below, including a map and references on beluga, and polar bear predation on beluga in this region.
Posted in Life History
Tagged Arctic Watch Beluga Foundation, beluga, beluga whale, Cunningham Inlet, Delphinapterus leucas, DFO, Gulf of Boothia, High Arctic, Lancaster Sound, Monodon monoceros, narwhal, polar bears, Prince Regent Inlet, Somerset Island