Monthly Archives: June 2020

Polar bear habitat in Canada and eastern Alaska compared at end of June 2012-2020

Here is a quick compare and contrast of sea ice habitat for polar bears in Canada and the Southern Beaufort region of eastern Alaska near the end of June, 2012-2020.

Baffin Island Bylot Sound bear_smaller_shutterstock_1144169858

Similarities between Hudson Bay ice/open water in the sea ice charts below are striking. Ice cover at the end of June shown in these charts since 2012 reinforces the fact, documented in the peer-reviewed literature, that there has been no continued declining trend in dates of sea ice breakup for Western and Southern Hudson Bay since 1998 at least (Castro de la Guardia et al. 2017; Lunn et al. 2016). WH bears are still on the ice.

As a consequence, recent declarations of impending doom for Hudson Bay polar bears, based on claims of reduced population size and health of these subpopulations – which in any case are statistically insignificant for WH and SH (Obbard et al. 2018; Dyck et al. 2017) – must be due to some other cause (Crockford 2020).

In all areas, winds rather than melt due to increased temperatures drive much of the expansion of open water at this time of year.

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My polar bear podcast interview with Anthony Watts from WUWT

A few days ago I had the pleasure of talking with Anthony Watts from WUWT as part of his new podcast series. Listen to it here.

Crockford podcast with Anthony Watts 19 June 2020

Below, I’ve copied a post from earlier this year that summarizes some misconceptions about polar bear conservation status and population size. I reiterate here (with links added for convenience) what I said last month:

The polar bear data are contradictory: contrary to predictions, several polar bear subpopulations (at least four of them) are indeed thriving despite much reduced summer sea ice [Chukchi Sea, Barents Sea, Kane Basin, M’Clintock Channel, as well as Foxe Basin and Davis Strait]. I have chosen to emphasis that good news, while Stirling and Derocher choose to emphasize the data that seem to fit their predictions [Western Hudson Bay and Southern Hudson Bay]. This is a classic conflict that happens all the time in science but presents no proof that I’m wrong or that the PragerU video is inherently ‘false’.

Note that Western Hudson Bay bears were last counted in 2016 but have had five good sea ice seasons in a row now, including this year by the look of it, so if ‘lack of sea ice’ is really the cause of the statistically-insignificant decline, then population numbers should be back up. And here is my video about the National Geographic video of the starving polar bear blamed on climate change mentioned by Anthony in the interview:

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No early breakup for W Hudson Bay sea ice again this year: polar bears still on the ice

No early breakup of Hudson Bay sea ice again this year: there is still extensive thick first year ice over most of Hudson Bay and all female polar bears fitted with tracking collars in Western Hudson Bay are still on the ice:

W Hudson Bay polar bears still out on the ice that’s packed together by winds. AE Derocher, 12 June 2020

Dercocher June 12 2020 tracking map Hudson Bay

Breakup of Hudson Bay sea ice as it relates to polar bear movement to land has been about the same since 1999 (about 2 weeks earlier than in the 1980s) and this year is shaping up to be no different: there is still no declining trend in date of sea ice breakup in Western Hudson Bay despite repeated predictions of imminent doom. An especially ‘early’ breakup year would have bears ashore before 15 June. Last year (2019) the first WH bear onshore was caught on film 5 July and problem bears were not recorded onshore in Churchill until the 2nd week of July.

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Spring feeding season almost over for polar bears & sea ice becomes less important

Here are ice conditions at the end of May, which signals the near-end of the critical spring feeding period for polar bears. This is because young-of-the-year seals take to the water to feed themselves, leaving only predator-savvy adults and subadults on the ice from some time in June onward (depending on the region).

masie_all_zoom_4km 2020 May 31_Day 152

Spring is the critical feeding period for polar bears (Crockford 2019, 2020; Lippold et al. 2020; Obbard et al. 2016):

“Unexpectedly, body condition of female polar bears from the Barents Sea has increased after 2005, although sea ice has retreated by ∼50% since the late 1990s in the area, and the length of the ice-free season has increased by over 20 weeks between 1979 and 2013. These changes are also accompanied by winter sea ice retreat that is especially pronounced in the Barents Sea compared to other Arctic areas. Despite the declining sea ice in the Barents Sea, polar bears are likely not lacking food as long as sea ice is present during their peak feeding period. Polar bears feed extensively from April to June when ringed seals have pups and are particularly vulnerable to predation, whereas the predation rate during the rest of the year is likely low. [Lippold et al. 2019:988]

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