Tag Archives: habitat

Polar bear habitat update: as much sea ice in 2017 as 2006 at 18 January

Sea ice charts for 18 January from NSIDC Masie show exactly as much sea ice in 2017 as there was back in 2006 – 13.4 mkm2.

masie_all_zoom_4km-2017-jan-18

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Polar bear habitat message for the year end: 2016 Arctic ice extent same as 2010

According to NSIDC daily sea ice interactive graph,  there was ever so slightly more ice on 31 Dec 2016 than on that date in 2010. However, the corresponding ice maps show just how differently that ice was distributed.

sea-ice-at-31-dec-2016_vs-2010_nsidc-interactive

Recall that in 2010, there was no huge die-off of polar bears attributed to reduced amounts of sea ice in the fall (or to reduced ice in summer, for that matter) because there was no catastrophic die-off at all.

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Polar bear habitat this fall shaping up fast – more like 2010 than 2007

Arctic sea ice tied 2007 for extent at the September minimum less than 3 weeks ago but with the refreeze proceeding much faster than 2007, seals will soon be returning to the ice edge and polar bears will be back to feeding like they did in 2010.

sea-ice-at-28-sept_2016_vs-2007_2012_5-point-0_nsidc-interactive

Sea ice extent less than 5.0 mkm2 lasted less than 6 weeks (23 August – 28 September), according to NSIDC.

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Hudson Bay update – lots of sea ice well positioned for polar bears to get ashore

There is slightly less ice this year in Hudson Bay than last year but it is hugging tight against the western shore, which means polar bears in Western and Southern Hudson Bay will be able to stay out on the ice (if they want to) until August.

Sea ice extent Canada 2016 July 15_CIS

The latest weekly ice graph from the Canadian Ice Service (for 9 July) below shows average ice coverage this year (and more than there was in 1976 and 1977):

Hudson Bay same week 9 July 1971-2016

[By the way, the IUCN Polar Bear Specialist Group website is still “under construction” allowing them to avoid mentioning the less-than-dire conclusions contained in the 2015 IUCN Red List assessment]

More ice maps below, comparing previous years.

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Late winter surge in sea ice habitat and the resilience of Svalbard polar bears

The Barents Sea – and Svalbard in particular – has had very little sea ice this winter but recent evidence suggests pregnant females adapted by moving east to Franz Josef Land to have their cubs. The surge in ice that’s come over the last few weeks will, however, be welcome habitat for the critical hunt of fat newborn seals that takes place primarily in April and May.

Svalbard polar bear_NP015991-isbjorn-JA

It was only last fall that Norwegian biologist Jon Aars (photo above taken by him in August 2015) was touting the fat condition of Svalbard-area polar bears he and his team saw in August and admitted the population had increased by a whopping 42% since 2004 – despite dire predictions of a drastic decline. In fact, 2014/2015 was a great year for the area’s polar bears.

However, in the fall of 2015 sea ice was so late forming around Svalbard that it seemed impossible that any females would get to traditional denning grounds on the east coast in time to give birth. There was no sea ice to speak of until late December, so it seemed virtually certain that all females had gone to Franz Josef Land further east (in Russia) – as they are known to do – to utilized its alternative denning sites.

It’s called resilience – the ability to shift behaviour in response to changing conditions. In this case, all indications are that shifting den locations to Franz Josef Land is a long-standing response of Svalbard area polar bears to low ice conditions. This shift does not even require a movement outside their subpopulation boundaries, let alone a movement outside the ill-defined “sea ice ecoregions” originally defined by Steven Amstrup and colleagues (2008) to support their prediction that polar bears will likely be extinct by 2100, taken up later by others since.

Some polar bear specialists appear to believe that if Barents Sea conditions are not precisely what they were in the 1980s (examples here and here), polar bears cannot possibly survive. But the bears are showing them otherwise – and demonstrating how they likely survived previous warm periods like the Holocene Optimum ~9,000 years ago and the Eemian Interglacial ~115,000-130,000 years ago (CERQA 2014:66) without population numbers getting anywhere near extinction levels.
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2016 record low maximum will make headlines but unlikely to affect polar bears

Never mind that the sea ice maximum this year came almost a month later than last year (and close to latest since 1979) – and was lower by only .02 – the US National Sea Ice Data Center (NSIDC) today trumpeted a new record low.  What this means to polar bears, if anything, remains to be seen.

Sea ice extent 2016 March 24 NSIDC_max 14_52mkm2 sm

2015: maximum set February 25 (day 56), at 14.54 mkm2

2016: maximum set March 24 (day 84), at 14.52 mkm2

[The difference in area? Smaller than the Islands of the Bahamas]

Latest maximum extent (since 1979) occurred in 2010 on April 2 (Day 92).

The average date for maximum extent is March 12.

I note, however, that given the lateness of the winter sea ice surge meant that the amount of ice present at 24 March 2016 (see NSIDC Interactive) was more than was present on the same date in 2006, 2007 and 2015.

Clearly, there was plenty enough sea ice in the spring of those years for most polar bears to hunt seals successfully and put on the weight they needed to survive the summer fast ahead. I see no reason to expect 2016 to be different.

Polar_Bear_male_Regehr photo_March 21 2010_labeled
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Polar bear survival: habitat 2013 vs. 2016 for 22 January

Using sea ice maps issued by the National Sea Ice Data Center (NSIDC), it’s interesting to compare these two years with respect to polar bear health and survival (keeping in mind that no polar bears live in what I like to call the armpits of the Arctic – the Sea of Okhotsk, the Baltic Sea or in the Gulf of St. Lawrence)1:

22 January 2016

Sea ice extent 2016 Jan 22 NSIDC

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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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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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