Tag Archives: spring feeding

Ice formation in W Hudson Bay slower than 2015 but not likely as slow as 1983

After a great start this year for Churchill-area polar bears of Western Hudson Bay – who came off the ice in better than usual condition after what must have been a good spring hunting season – ice maps suggest that freeze-up will be later than last year, an impression confirmed by on-the-ground observers.

Ice coverage this year at 7 November (2016):

sea-ice-extent-canada-2016-nov-7_cis

Ice coverage last year at this date (7 November 2015), see this post for details:
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Tracking polar bears in the Beaufort Sea – all bears on the ice in June

The recent open water in the Southern Beaufort didn’t seem to change what polar bears were doing – bears tracked by USGS show them on the ice, likely trying to hunt. More ice edge means more hunting habitat at this time of year.

Beaufort tracking USGS bear-movements-June 2016 lg closeup

However, few hunts are likely successful at this time of year – because only older seals are on the ice and the broken ice makes escape so much easier for the seals (see previous post here). Fat bears on shore this summer (like the ones seen at Kaktovik in September) will tell us that they got enough to eat earlier in the season. Note that bears in good condition that appear at the whaling bone piles in September are there by choice (not stranding) and they got fat by feeding in the spring (March-May), not by picking at leftover whale scraps. Calories from terrestrial sources (for most bears) just reduce the amount of weight they lose over the summer.

More maps below. Continue reading

Critical spring feeding for polar bears is over – sea ice levels are now irrelevant

Polar bears in virtually all regions will now have finished their intensive spring feeding, which means sea ice levels are no longer an issue. A few additional seals won’t make much difference to a bear’s condition at this point.

Relative importance of seasons polar bear graphic_PolarBearScience_June2016

The only seals available on the ice for polar bears to hunt in early July are predator-savvy adults and subadults but since the condition of the sea ice makes escape so much easier for the seals, most bears that continue to hunt are unsuccessful – and that’s been true since the 1970s. So much for the public hand-wringing over the loss of summer sea ice on behalf of polar bear survival! Continue reading

Ice maps vs. observations in the W. Arctic – polar bear habitat reality check

Last Wednesday (8 June 2016), the US Coast Guard rescued walrus hunters from Shishmaref in the Bering Strait who got stuck in sea ice that is barely visible on sea ice maps. It’s a rare glimpse of what sea ice really looks like up close compared to what you see on the ice maps.

Watch the video here: https://www.dvidshub.net/video/embed/467959

[Unfortunately, the screencaps from the video, like the one below, are less impressive than the film. In the video, you can see the hunters walking on the ice around their trapped boat – the ice does not visibly move]

Shishmaref_ice_CoastGuard 02_8 June 2016

Have a look at the sea ice maps below for the day the incident took place. They show what appears to be hardly any ice in the area.

This is a good lesson for assessing what’s been going on in the Beaufort Sea a bit further east, where winds and currents have opened up a rather large patch of open water surrounded by considerable expanses of sea ice – at issue is the possible impact on polar bear spring feeding for April and May.
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Harp seal: most abundant Arctic seal is an undervalued polar bear prey species

The harp seal is the most abundant seal species in the northern hemisphere (estimated to number more than 9 million animals – that’s more harps than ringed seals) but are found only in the North Atlantic. Partly because they give birth on mobile pack ice, harps have their pups earlier in the season than all other Arctic seals, which means that in some regions, they are a critical food source for polar bears that have eaten little over the winter months.

Harp seal pup_DFO Newfoundland

Although young ringed seals are considered the primary prey of polar bears throughout the Arctic, young harp seals undoubtedly represent an increasingly important resource for populations of Davis Strait, East Greenland and Kara Sea bears.

Most of the harp seals in the NW Atlantic/Atlantic Canada (about 80% of them) have their pups off Newfoundland and Labrador, an area known as the “Front” (the location of my polar bear attack novel, EATEN: special deals all this week). Harps seals at the Front now provide a huge prey base for polar bears of the large (and possibly still growing) Davis Strait subpopulation (photo below courtesy DFO Canada).

There are an estimated 7.4 million harps in Atlantic Canada today (range 6.5-8.3m), an exponential increase over the early 1980s, when perhaps only half a million so remained.  Pagophilus groenlandicus was assigned a conservation status of ‘Least Concern’ by the IUCN Red List in June last year (Kovacs 2015), when it was estimated that the global population size of the harp seal was greater than 9 million animals and probably growing1, 2 due to reduced human hunting:

“…harp seals have been harvested for thousands of years but currently the population is large and the number of animals harvested is declining.” [my bold]

Photographers and animial rights activists love cute, fluffy harp seal pups and rarely mention the carnage that goes on in spring as polar bears devour the naive youngsters. See the video below (from 2008), for an example of the cuteness factor.

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Polar bear habit update – day 333 Arctic sea ice hits 11.1 mkm2

It’s just past the height of fall in the Arctic (Oct-Dec) and polar bear habitat is expanding day by day: according to NSIDC Masie ice charts, the ice has now surpassed 11 mkm2 in extent. Fall is the second most important feeding period for polar bears after spring.

masie_all_zoom_4km 2015 day 333_Nov 29

Only the Barents and Kara Seas (north of Norway and western Russia) are short of ice right now, similar to conditions seen in the fall of 2013. Last fall (2014), conditions were much better and as a consequence, researchers saw a lot of females with healthy cubs in the spring of 2015.

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