Category Archives: Sea ice habitat

Polar bear habitat update – Arctic sea ice today covers same area as it did on June 30

Arctic refreeze is well underway. Less than half way through the Arctic autumn (Oct-Dec), polar bear habitat on 11 November 2015 covered the same total area as it did on the last day of Arctic spring (April-June); it’s just distributed differently.

polar_bear_usfws_no date_sm

Yesterday, courtesy NSIDC Masie

masie_all_zoom_4km_2015 Nov 11

Here is what 30 June 2015 ice extent looked like, with the same amount of ice coverage:


For the week of 12 November, Hudson Bay sea ice development is well underway, with more ice in the north than there has been in many years; Davis Strait ice is the highest this week since 1999 and Baffin Bay ice coverage is above average. Foxe Basin and the Beaufort Sea are both approaching maximum coverage, which means bears there will be back out on the ice hunting. Chukchi Sea ice has finally surrounded Wrangel Island but the Svalbard Archipelago in the Barents Sea is still ice-free. More ice maps and charts below.
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Specialists mum on low Chukchi Sea polar bear habitat this summer and fall

You may or may not have noticed that even though Chukchi Sea ice coverage has been way below average this melt season, there has been no hue-and-cry about poor suffering Chukchi polar bears. That’s because polar bear biologist’s own research has shown that the health and survival of these bears has not been negatively impacted by low summer sea ice. There may be threats from poaching in Russia, but not lack of summer sea ice.

Chukchi vs Beaufort ice at 29 Oct 2015_polarbearscience

As of this date, developing sea ice is only just approaching Wrangel Island, a major polar bear denning region in the Chukchi Sea, see maps below (Ovsyanikov 2006).

Yet, polar bear specialists insist that neighbouring Beaufort Sea bears – who endure a much shorter open-water season – are in peril of extinction because of scarce summer sea ice.
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Hudson Bay freeze-up moving faster than recent years, WHB polar bear habitat imminent

There may not be ice for Western Hudson Bay polar bears to walk on yet but there is still more ice forming along the northwest shore of the bay than last year at this time or even the year before. The Canadian Ice Service (CIS) map for 5 November shows this early formation.

Canadian Arctic Nov 5 2015_CIS

What’s present is mostly grey ice defined by CIS as:

“Young ice 10-15 cm thick, less elastic than nilas [a kind of new ice] and breaks on swell. It usually rafts under pressure.”

Polar bears generally need ice about 30 cm thick to support their weight, which could take a day or two – or a week or two, depending on the weather in northwestern Hudson Bay. For Churchill, along the central coast of western Hudson Bay, ice thick enough for walking will not likely be far behind, given the long-range forecast of freezing weather. In recent years, most Churchill polar bears have left the ice by around 20 November. More maps and graphs for this week below.
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Discovery News spreads old misinformation about W. Hudson Bay polar bears

In a just-released Discovery News piece, Kieran Mulvaney (4 November 2015, “In the polar bear capital, an uncertain future) repeated three misleading statements about Western Hudson Bay polar bears that keep making the rounds, despite the fact they have been laid to rest by the latest scientific reports on  (Lunn et al. 2013, 2014; Stapleton et al. 2014). I reviewed these just a few weeks ago.

Western Hudson Bay bear, Wakusp National Park, August 2011.

Western Hudson Bay bear, Wakusp National Park, August 2011.

1) “Climate change is causing the bay’s ice to melt earlier and freeze later, causing bears to spend longer a shore.”

Not true. Lunn and colleagues stated explicitly that there has been no trend in either break up or freeze-up of WHB sea ice since 2001. Although there has been large variability in dates, that lack of trend that has continued to this year.

2 & 3) “As a consequence, Churchill’s polar bears are decreasing in number (from approximately 1,350 three decades ago to roughly 900-1,000 now) and in physical condition.”

This deliberately misleading statement avoids the fact that the latest surveys found roughly the same number of bears in 2011 as in 2004 (the estimate used by the IUCN Polar Bear Specialist Group for WHB is 1030) when different counting methods were taken into account. The ~900 bear estimate came from the mark-recapture survey, which left out a portion of the range that the aerial survey covered, hence the official estimate of 1030.

In addition, there has been no scientific assessment of body condition or cub survival since before the last population estimate in 2004 – polar bear “experts” keep telling journalists there are declines but have yet to produce any data to support those claims. The latest surveys did not collect data on body condition or cub survival.

Mulvaney’s misinformation is almost certainly the result of spending time in Churchill with activist Polar Bears International spokesperson Steve Amstrup and activist climate scientist Katherine Hayhoe doing webcasts (e.g. “Challenges of communicating climate change”).  

Mulvaney is clearly not a journalist or a science writer: if he was, he would do some research of his own and stop believing as gospel every word that activist scientists feed him. They are using him as a mouth-piece and sadly, Discovery News is buying it all and presenting it as science.

[Hayhoe, by the way, blocked me on twitter earlier this morning for making one observational comment, my first-ever to her account, in response to a conversation about polar bear population numbers. This is what I said that Hayhoe does not want her followers to know:

“Stop wanton slaughter, #’s go up, works for all species. S Beaufort #polarbear #s dipped due to thick spring #seaice”

Both statements are true and supported by scientific literature. But Hayhoe is all about “climate communication” which appears not to allow science to intrude.]

Lunn, N.J., Regehr, E.V., Servanty, S., Converse, S., Richardson, E. and Stirling, I. 2013. Demography and population assessment of polar bears in Western Hudson Bay, Canada. Environment Canada Research Report. 26 November 2013. PDF HERE

Lunn, N.J., Servanty, S., Regehr, E.V., Converse, S.J., Richardson, E. and Stirling, I. 2014. Demography and population assessment of polar bears in Western Hudson Bay, Canada. Environment Canada Research Report. July 2014. PDF HERE [This appears to be the version submitted for publication]

Stapleton S., Atkinson, S., Hedman, D., and Garshelis, D. 2014. Revisiting Western Hudson Bay: using aerial surveys to update polar bear abundance in a sentinel population. Biological Conservation 170:38-47.

Tracking polar bears in the Beaufort Sea – all three bears on the ice during October 2015

All three of the females with radio collars installed by USGS last spring (see footnote below) spent October out on the sea ice – which suggests the Kaktovik female with the tight collar that made the news last week was either wearing a failed collar, USGS removed her icon from the map, or she was not wearing a USGS collar.

polar-bear-radio-collar_CBC Oct 28 2015

It is possible that the poor bear was the one represented by the purple icon from last month (see map below), the only USGS collared bear that was on shore during September and still sending signals. The bear in the above photo was photographed in Kaktovik, easy walking distance for a bear, near the end of October.  The purple icon on shore in the September USGS map is no longer present this month.

As far as I know, there has been no follow-up information on the fate of this bear: we still don’t know whether the collar has yet been successfully removed.
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2015 may be the earliest in many years that W. Hudson Bay polar bears head for the sea ice

Great news for Western Hudson Bay polar bears! Following up from sea ice conditions last week, CIS maps show ice forming all along western Hudson Bay – not a huge amount, but the beginning of the end of the ice-free season, which recently has not occurred until mid-November (Cherry et al. 2013).

Canadian Arctic Oct 29 2015_CIS

There is above-average sea ice coverage in Foxe Basin and Davis Strait, and only slightly below average coverage in the Beaufort Sea (see graphs below). Polar bear habitat is shaping up very nicely indeed across Canada and the US this year.
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Beaufort Sea polar bear habitat highest since 2008 at this date

Good news for Southern Beaufort polar bears! Sea ice converging on the north shore of Alaska earlier than any year since 2011 at least, according to NSIDCs regional ice plots (below).


But wait, their Masie ice maps show it’s actually the earliest since 2008 (although the ice movement onshore was also earlier than 2006 and 2007, see below). And it’s still a full week before the end of October, the first month of Arctic fall (October-December). Lot’s of seal hunting habitat.

This emphasizes the fact that the primary problem faced by Southern Beaufort sea polar bears is not scarce summer ice but by thick sea ice conditions in the spring. Bears photographed near Kaktovik this year were in excellent condition (see here and here, taken by Kelsey Eliasson, Polar Bear Alley). If folks have been seeing starving bears, they haven’t said anything that I’ve been able to find.

Ice maps below.
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