Tag Archives: seals

Polynya refresher: open water in spring is due to winds & currents, not ice melt

Arctic sea ice begins to open up in spring at predictable locations due to currents and prevailing winds and this was as true in the 1970s as it is today. Polynyas and widening shore leads that most often get mistaken for early sea ice melt are those in the Beaufort and Chukchi Seas and in Hudson Bay.

Beaufort Sea male polar bear USGS_2005 Amstrup photo

But contrary to concerns expressed about possible negative implications of these early patches of open water, these areas have always been critical congregation areas for Arctic seals and are therefore important feeding areas for polar bears.

Seal habitat frozen open lead_Beaufort 2008_Miller

Seals hauled out beside a lightly frozen over lead in Beaufort Sea ice, 2008. USFWS.

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Low Bering Sea ice mostly due to south winds, no data on an impact for polar bears

Sea ice in the Bering Sea this winter was said to be the lowest since the 1850s, largely driven by persistent winds from the south rather than the usual north winds although warm Pacific water was a factor early in the season (AIRC 2018). But what, if any, impact is this surprisingly low winter and spring ice cover likely to have on Chukchi Sea polar bear health and survival?

Rode and Regehr 2010_Chukchi_report2010_Fig1_triplets_labelled

In fact, research on Chukchi Sea polar bears has included so few examples of individuals utilizing the Bering Sea in winter (Jan-March) and early spring (April-May) that any conclusions regarding an impact from this year’s sea ice conditions are likely to be invalid. In short, we don’t know what will happen since it has not happened before within living memory; the opinions of polar bear specialists must be taken with a grain of salt because so many of their previous assumptions have turned out to be wrong (Crockford 2017a,b, 2018), see here, here, and here. Seals, walrus and polar bears are much more flexible and resilent to changes in habitat conditions than most modern biologists give them credit for and consequently, it will be fascinating to see how the ice will change over the coming months and how the animals will respond.

Sea ice extent 2018 March average NSIDC

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Polar bear habitat update early spring 2018

Spring in the Arctic is April-June (Pilfold et al. 2015). As late April is the peak of this critical spring feeding period for most polar bear populations, this is when sea ice conditions are also critical. This year, as has been true since 1979, that sea ice coverage is abundant across the Arctic for seals that are giving birth and mating at this time as well as for polar bears busy feeding on young seals and mating.

Polar_Bear_male on sea ice_Alaska Katovik Regehr photo_April 29, 2005_sm labeled

Below is a chart of sea ice at 25 April 2018, showing sea ice in all PBSG polar bear subpopulation regions:

masie_all_zoom_4km 2018 April 25

Some Arctic subregions below, in detail. Continue reading

Winter polar bear sea ice habitat by early March 2018 varied little from 2006 or 2017

Here’s a polar bear habitat update for early March: some folks are wringing their hands over the relatively extent of ice this season but ice maps show that as far as polar bear habitat is concerned, conditions are not materially different this year from what they were in 2006 or 2017. There is still plenty of late winter sea ice for polar bears needing a platform from which to hunt Arctic seals, which in some areas will have already begun giving birth to their fat furry pups (harp seals first, other species later).

The MASIE map for 5 March 2018 (Day 64) shows ice extent at 14.5 mkm2:

masie_all_zoom_4km 2018 March 5

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State of the Polar Bear Report 2017 shows polar bears are thriving

My new report reveals that polar bears are doing well despite recent reductions in sea-ice. It shows in details why this is so, with summaries of critical recent research.

Press release and pdf below. And read my op-ed in the National Post here.

State of Polar Bear Report cover_12 Feb 2018 image with bottom
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USGS ‘treadmill’ paper repeats bogus claim that ice loss harmed polar bears

The newest polar bear science paper making the rounds courtesy the US Geological Survey, is a perfect example of a statistically-significant result with no biological significance. While the results are rather lame, the paper is dangerous because it repeats the disingenuous claim (see Crockford 2017) that Southern Beaufort Sea polar bear numbers declined in recent years due to summer sea ice loss.

polar_bear_rubble_ice_Mike Lockhart USGS_8 April 2011

The USGS authors (Durner et al. 2017) know this harm-from-summer-ice-loss assertion is not true for the Southern Beaufort subpopulation but the more papers they can get into print that say so, the more likely it will be believed — and the less likely readers will check older literature that documents the recent decline in polar bear numbers was due to a three year period (2004-2006) when thick ice conditions in spring made seal hunting a challenge, a repeat of a well-known phenomenon (e.g. Stirling et al. 1980; Stirling 2002) unique to this region that has been documented since the 1960s.

The Durner paper (USGS press releaseIncreased Sea Ice Drift Puts Polar Bears on Faster Moving Treadmill” published online 6 June ahead of print) spins the research results as potentially significant bad news but in so doing reveals how desperate they have become to make the public and their biology colleagues believe that Southern Beaufort polar bears, among others, are being negatively affected by summer sea ice loss (as per Stirling and Derocher 2012).

Durner, G.M., Douglas, D.C., Albeke, S.E., Whiteman, J.P., Amstrup, S.C., Richardson, E., Wilson, R.R. and Ben-David, M. 2017. Increased Arctic sea ice drift alters adult female polar bear movements and energetics. Global Change Biology. DOI: 10.1111/gcb.13746 http://onlinelibrary.wiley.com/doi/10.1111/gcb.13746/abstract [paywalled]

In fact, the Durner et al. paper does not document any harm to polar bears from the proposed ‘treadmill’ effect of more rapidly moving ice for the period 1999-2013 compared to 1987-1998, but instead uses models to suggest bears might have to eat one to three more seals per year to compensate for the extra energy needed to walk against the moving ice. That’s right: perhaps only 1 more seal per year out of the 50 or so they would usually consume (see Stirling and Øritsland 1995). In my opinion, that’s a pretty lame result for what one of the co-authors described as an immense amount of work.

News outlets have essentially used the USGS press release as a click-bait lede for another round of Trump-bashing with respect to the Paris climate change agreement, see here and here: the stories are hardly about polar bears at all. And predictably, polar bear activist and co-author Steven Amstrup (paid spokesperson for Polar Bears International, famous for their “Save Our Sea Ice” campaign) appears to be using the same approach: an up-coming call-in talk radio program at NPR’s Anchorage affiliate KSKA for Tuesday 13 June at 10:00 (Alaska time, see “Talk of Alaska”) is being billed as a discussion of “polar bears, climate change, and the Paris Accord” (h/t AK geologist). Continue reading

An El Niño year late start to freeze-up on Hudson Bay: bears gearing up to hunt

There is no serious ice on the west shore of Hudson Bay yet (as the map below shows) but the winds have just shifted – instead of coming from the south, they are now blowing in from the north.

Freeze-up and a resumption of seal hunting for Western and Southern Hudson Bay polar bears looks imminent. The bears get out on the ice as soon as they are physically able, when the ice is about 3-4 inches thick (about 10 cm).

sea-ice-extent-canada-2016-dec-5_cis

I’m going to let Kelsey Eliasson from PolarBearAlley, on shore at Churchill, convey the gist of the freeze-up situation on the Bay.

Recall that freeze-up was late in both 1998 and 1999 – during the height of that strong El Niño warmth as well as the year following. Continue reading