Posted onDecember 11, 2022|Comments Off on Polar bear habitat update: Winter conditions well on their way across the Arctic except in Svalbard
December is late fall in the Arctic: winter conditions are gearing up but are not in full swing everywhere. Sea ice is developing quickly over Hudson Bay and moving slowly towards the Bering Sea but the Svalbard archipelago is still devoid of pack ice.
Such conditions north of Norway have existed most years since 2005: it’s certainly not a new development for Svalbard to be free of surrounding pack ice in December (although there was lots of ice in 2019 and 2021 by late November). This means traditional denning areas on the eastern islands again cannot be used by pregnant polar bear females, because they must be ensconced in their dens by at least late November or so.
Some seem to think this is a calamity: that such ‘loss of habitat’ is a huge concern for the survival of the subpopulation, if not the entire species. However, the same conditions existed in 2011 and did not result in a dramatic decline in the population as measured in 2015 (Aars et al. 2017) because the bears knew how to respond. They have apparently moved north to make maternity dens on the sea ice or east to the Franz Josef Land archipelago in Russia (Aars 2015). These areas are still within the Barents Sea subpopulation boundaries and researchers have known for two decades that bears have moved around within it (Andersen et al. 2012; Derocher 2005; Maurizen et al. 2002).
Posted onDecember 1, 2021|Comments Off on Higher than average Svalbard sea ice extent in November 2021 has implications for birth of cubs
Early last November, sea ice around Svalbard was the lowest it had been since 1967 and pregnant females were simply unable to den on the eastern islands of the archipelago and instead had to make their dens and give birth in the pack ice or the Franz Josef Land archipelago further east, as they have done before. However, the ice is back this fall with a vengeance: even Hopen Island in the south of region was surrounded by ice well before the end of the month but whether it will attract a few pregnant females remains to be seen.
Posted onDecember 16, 2015|Comments Off on Barents Sea polar bears adapt to changing sea ice conditions
Sea ice development in eastern Svalbard this fall is lagging well behind the rest of the Arctic. Several polar bear researchers (e.g., Andrew Derocher here and here) have recently been raising the alarm that this might be devastating for Barents Sea females looking for suitable denning sites.
The implication is that pregnant polar bear females are inflexible – so fixated on one location to give birth that they are unable or unwilling to choose an alternative if conditions preclude using their preferred location this year. However, the available facts do not support such a pessimistic attitude. Continue reading
Comments Off on Barents Sea polar bears adapt to changing sea ice conditions
Posted onDecember 1, 2015|Comments Off on 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.
Posted onApril 14, 2014|Comments Off on Polar bears move around as sea ice habitat changes – this is what resilience looks like
Oddly, it seems some people expect polar bears to sit around and suffer (or die) when local conditions deteriorate, rather than move elsewhere.
While there are perhaps a few places where moving is not really an option over the short term, over the long term (more than one season) polar bears are free to shift to another locale if ice conditions change (either too much ice or too little).
An announcement by the WWF last week (10 April) caught my eye, as it talked about bears moving from one area to another because of changing ice conditions — as if this was surprising, extraordinary and newsworthy. That said, at least they weren’t suggesting the bears are all going to die because of declining ice, which is a huge improvement.
See what you think of this part of the press release (below), in the context of what we know about the movement of bears between regions:
Posted onOctober 15, 2013|Comments Off on Barents Sea polar bear status and sea ice declines
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]
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