Category Archives: Life History

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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New report: Harp seal population critical to Davis Strait polar bears is still increasing

The report on the latest population estimate for harp seals off the east coast of North America was released in late March without fanfare and therefore no media attention. This was one of the missing scientific reports mentioned in my State of the Polar Bear Report 2019 released in February (Crockford 2020): results of surveys promised for months or years by early 2020 but not delivered.

Harp seal on ice around PEI _DFO 2017

Not surprisingly then, we find the report has good news: the population estimate of harp seals in the NW Atlantic has risen to about 7.6 million (range 6.55-8.82) animals (DFO 2020), up from 7.4 million in 2014 (DFO 2014).

Note that the survey was done in March 2017, a low ice year for the Gulf of St. Lawrence (see discussion below) and while this may have resulted in some increased mortality for pups born there, it is also known that many ‘Gulf’ pregnant females will instead have given birth off Newfoundland and Labrador in a whelping region called ‘The Front’. Apparently, these factors were accounted for in the population model.

Harp seal pups born at the Front are an important food for Davis Strait polar bears. This increase in the prey base for Davis Strait polar bears suggests the bear population may have grown substantially since the last survey in 2007 (Peacock et al. 2013; Rode et al. 2012). Davis Strai is the only subpopulation of polar bears officially considered to have ‘likely increased’ at 2018 by Environment Canada. A new Davis Strait population size survey was apparently completed in 2018 but the results are not yet available (Crockford 2020).

Harp seal pup_DFO Newfoundland

Highlights, quotes, and figures from the harp seal report below. Continue reading

Sea ice more than 1.2m thick over Hudson Bay portends a good year for polar bears

The chart below shows what sea ice thickness over Hudson Bay was like at the first week of May in a so-called a ‘good year’ (2019) – when polar bears came off the ice in excellent condition late in the summer and left early in the fall (‘thick first year ice’ is dark green and indicates ice greater than 1.2m thick):

Hudson Bay weekly stage of development 2019 May 6

Hudson Bay ice conditions this year appear to be shaping up to be as good or better than last year for polar bears yet specialist researchers and their cheerleaders have still been claiming that bears in this region – Western and Southern Hudson Bay – are doomed because of poor ice conditions. It’s no wonder they still haven’t published the data they’ve been collecting on polar bear body condition and cub survival over the last 15 years or so (Crockford 2020). With most field work cancelled for this year, what’s their excuse for not getting that done?
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New Paper: Body condition of Barents Sea polar bears increased since 2004 despite sea ice loss

A recent paper that attempted to correlate pollution levels and body condition in Barents Sea polar bears reports it found body condition of female bears had increased between 2004 and 2017 despite a pronounced decline in summer and winter sea ice extent.

Svalbard polar bear Jon Aars_Norsk Polarinstitutt

“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” [Lippold et al. 2019:988]

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Earth Day surprise: video of fat polar bear on Arctic sea ice contains no false facts

Shot during the 2015 Arctic GEOTRACES expedition aboard the U.S. Coast Guard Cutter Healy. The lack of narrated misinformation makes this video suitable for young children.

This looks to be a different bear than the one I discussed in 2015 here but was undoubtedly taken on the same cruise, because reports at the time (August 2015) said that ‘several’ bears were spotted. Video attributed to ‘Bill Schmoker, PolarTrek teacher 2015’, launched on the Woods Hole Youtube channel 1 April 2020 (no other info provided).

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Winter sea ice maximum extent on March 5 was the highest since 2013

The most positive thing that US National Snow and Ice Data Center sea ice experts could say about this year’s winter sea ice maximum was that it wasn’t a record breaker. But it provides ample polar bear habitat when the bears need it most: just before the critical spring feeding season.

Sea ice extent 2020 March 5_sea ice maximum called_15 point 05 mkm2 NSIDC 24 March

In fact, they said: “The 2020 maximum sea ice extent is the eleventh lowest in the 42-year satellite record, but the highest since 2013.”  All that winter ice is essential polar bear habitat just before the critical spring feeding season (Crockford 2019, 2020) and it’s one of the reasons that polar bears are thriving.

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Amid viral pandemic UK photographer captures images of Canadian polar bear cubs

The Sun ran a photo-essay yesterday (22 March 2020, below) taken by a UK photographer who went to Wapusk National Park just south of Churchill, Manitoba in order to get much-coveted images of polar bear mothers and cubs newly emerged from winter maternity dens. The photos were said to have been taken “early last week” (16-17 March?).

Sun pb emerging with cubs feature 22 March 2020 lead photo

The trees in the photos are a give-away to the location: no other subpopulation regions except Western and Southern Hudson Bay are below the treeline. Scrubby little spruces but ‘trees’ nonetheless. Mothers in more northern regions won’t come out with their cubs until April.

The question is: what was this photographer thinking to travel to a remote Arctic location in the middle of a global pandemic?

UPDATE 24 March 2020 820am PT. I have just heard from photographer Brian Mathews and he had this to say about his trip to Wapusk National Park:

“Context and facts are key as ever. I left the U.K. before any of the measures where in place. I’ve just got back after being in Canada for nearly a month. When I returned to Churchill I self isolated then returned to the U.K. the coverage I got is good for the bears and the positive uplifting feedback I’ve had about the joy they brought into people lives had be brilliant.”

I noted in my response to him that I realize the tour company in Canada bears some responsibility for continuing to operate under the circumstances.

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