Tag Archives: Hudson Bay freeze-up

Polar bear habitat this fall shaping up fast – more like 2010 than 2007

Arctic sea ice tied 2007 for extent at the September minimum less than 3 weeks ago but with the refreeze proceeding much faster than 2007, seals will soon be returning to the ice edge and polar bears will be back to feeding like they did in 2010.


Sea ice extent less than 5.0 mkm2 lasted less than 6 weeks (23 August – 28 September), according to NSIDC.

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W Hudson Bay polar bears now on the ice hunting but killer whales could be trapped

According to reports from folks on the ground in Western Hudson Bay, most polar bears were out on the ice resuming seal hunting by the 20th or 21st November at the latest (some got started quite a bit earlier). That’s less than 2 weeks later than the average date in the 1980s (which was November 8).

Sea ice Canada 25 Nov 2015_with Churchill

However, the rather odd pattern of freeze-up this year may not be good news for any killer whales still remaining in Hudson Bay – their access to the open ocean is already virtually blocked by ice.

UPDATE 26 November 2015: What a difference a day makes! Look at the spectacular ice development overnight along the west coast of Hudson Bay and in the central portion of the bay since yesterday (below).

Canadian Arctic Nov 26 2015_CIS

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Polar bear specialist says there are 800 polar bears in W Hudson Bay, gov’t says ~1,000-1,500

Activist polar bear biologist Andrew Derocher (University of Alberta) may have gone too far this time. In an interview with Yahoo News, Derocher is quoted as saying:

“When I first started here about 30 years ago the population was about 1,200 bears and now we’re down to about 800,” team member Andrew Derocher, a biology professor at the University of Alberta, said in a phone interview from the tundra outside Churchill.”  [my bold]

Figure 4. Environment Canada's "Map 3: 2014 Canadian Polar Bear Subpopulation and Status Map," original here.

Environment Canada’s “Map 3: 2014 Canadian Polar Bear Subpopulation and Status Map,” original here. Click to enlarge.

However, the Polar Bear Technical Committee of Environment Canada says differently: it estimates there are ~1000-1,500 bears in Western Hudson Bay (WH) and that the population is probably stable, as their new status map (dated June 2014, copied above) shows. A recent (2014) peer-reviewed paper by Stapleton and colleagues (discussed here) provides the data for that estimate.
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What polar bear habitat could look like in another 5-6 weeks

According to the National Snow and Ice Data Center (NSIDC, Sept. 20 report), the annual sea ice minimum extent was reached on Sept. 13, 2013.

At 5.10 million square kilometers, this year’s low was a whopping 1.69 million square kilometers above the minimum extent for 2012 (which was the lowest since 1979) and well within two standard deviations of the 1979-2010 average. (Two standard deviations: “Measurements that fall far outside of the two standard deviation range or consistently fall outside that range suggest that something unusual is occurring that can’t be explained by normal processes”).

The minimum extent for 2013 is virtually indistinguishable from the minimum for 2009, which was 5.13 million square kilometers. The ice was distributed a bit differently in 2009 – more in the east and less in the west — than it was this year (see Fig. 1 below).

Figure 1. Using the JAXA “Sea ice monitor” feature, I plotted the date the 2013 minimum was reached (September 13, 5.10 million square kilometers, white) with an overlay (purple) for the same date back in 2009 (September 13, 2009, 5.13 million square kilometers), when that year’s minimum was reached (according to the NSIDC report). Areas of overlap are pink.

Figure 1. I used JAXA to plot the date the 2013 minimum was reached (September 13, 5.10 million square kilometers, white) with an overlay (purple) for the same date back in 2009 (September 13, 2009, 5.13 million square kilometers), when that year’s minimum was reached. Areas of overlap are pink.

You’ll know from previous discussions here that the annual minimum reached in late summer has little impact on polar bear health and survival (see excellent summary of the evidence for that here). What matters most to polar bears is the presence of ample ice in spring and early summer (March-June), which is their critical feeding period.

But after the fast that many polar bears endure over the height of the summer, they are eager to get back onto the ice and resume hunting. When in the fall does that become possible?

I wondered what the similarity in extent for 2013 and 2009 might tell us about polar bear habitat development over the next month or so.

In other words, what might polar bears this year expect in the way of sea ice development by say, the end of October? When might they be able to start hunting?

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Cannibalism in polar bears: spin and misrepresentation of fact galore

In my next to last post, I discussed some of the anecdotal reports of den collapses included in the peer-reviewed summary of facts presented by biologists Ian Stirling and Andrew Derocher (2012) that supposedly support the premise that global warming is already having an impact on polar bear populations (discussed previously here, here, and here), prophesied to be even greater in the future. While they admit that such reports are not based on scientific studies, they nevertheless include them in their published list of global warming impacts, and not surprisingly, that is how others have interpreted them.

The same is true for their treatment of the phenomenon of cannibalism in polar bears. In that same paper, Stirling and Derocher (2012:2701) have a section called “Anecdotal observations consistent with predictions of the effects of climate warming.” This section begins with a discussion of cannibalism:

“There have been several well-publicized observations that are consistent with predictions of the effects of climate warming on polar bears, but cannot be statistically linked. For example, intraspecific aggression and cannibalism were predicted to increase in polar bears with climate warming (Derocher et al. 2004, Table 1). Observations of infanticide and cannibalism by thin adult males on land during the open water period have been documented (e.g., Lunn & Stenhouse, 1985; Derocher & Wiig, 1999; Amstrup et al., 2006; Stone & Derocher 2007). Such events have been known to occur for many years and, although their significance is unclear, there is some evidence suggesting the frequency of occurrence is increasing in areas where bears fast on land for extended periods. ” [my bold]

And this is the evidence for the supposed increase in occurrence:

“For example, in late summer and autumn 2010 [sic], there were eight observations of cannibalism on the western coast of Hudson Bay compared to one or two in the previous 5 years (I. Stirling, unpublished data).” [my bold; 2010 should be 2009 – more on this later.]

Were these observations of cannibalism made by polar bear researchers or someone else? Were there as many observers in the area in each of the five years prior to the year they occurred, as there were when these incidents were observed? We don’t know, because it’s unpublished data.

Stirling and Derocher have again included critical information in their list of facts that has not been published. I guess I’ll have to add “evidence for cannibalism” to my previous list of “Critical evidence on polar bears in W. Hudson Bay is unpublished” (see also “Stirling and Derocher’s sea ice trick) [there is more information available, but it’s not from peer-reviewed sources – more on this below]

In this post, I take a look at some of the evidence that is published, some of the media interviews and reports that followed, and the information that came from a press release issued by an advocate group. I’ve made a table summarizing the details of all recent papers and reported incidents, and some of them are described in more detail. In a footnote, I have a brief summary of why polar bears kill and eat each other.

These details reveal some rather shocking evidence of scientists misrepresenting evidence – in their peer-reviewed papers and in interviews with the media – and bathing their global warming prophesies in the blood-lust of cannibalism. It’s past time to shine a big bright light on the cannibal issue, so pardon the length of this post.

[See followup post April 19 here]

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Polar bears of W. Hudson Bay came ashore in 2009 as late as in 1992

It’s like pulling teeth, getting up-to-date information on breakup dates of Hudson Bay sea ice. You’d think with the importance of this seasonal event to the polar bears of Hudson Bay (some of which, we’re told, face the most perilous future of all polar bears worldwide), we’d get a press release every summer alerting us to the precise date of sea ice breakup and the subsequent arrival of the bears onshore. I’m thinking of something similar to the dispatches we get from the National Snow and Ice Data Center (NSIDC) when Arctic sea ice reaches its yearly maximum (e.g. March 2012) and its yearly minimum extent (e.g. September 2012).

Sadly, this is not the case.

So I was intrigued to see that a new paper just out in the Journal of Animal Ecology, by Seth Cherry (a Ph.D. student of Andrew Derocher) and colleagues, dealt with Hudson Bay breakup dates. I was hoping for some data beyond 2007, which has been the limit of information provided so far by polar bear biologists (see previous posts here and here). Unfortunately, because the methods for determining breakup dates in this paper are so different from previous ones (more detail below), the new data (1991-2009) can’t be compared to earlier studies that go back to 1979. But there is some good news.

Although you wouldn’t know it by the author’s conclusion, the results of the study confirm for this region my previously stated contention that polar bears need spring and early summer ice (March through June) for gorging on young, fat seals and documented declines in sea ice have rarely impinged on that critical feeding period – by which I meant, bears have seldom, if ever, been forced off the ice of Hudson Bay as early as June.

The study also confirms that there has not been any kind of spectacular retreat of sea ice breakup dates – coming earlier and earlier in the season – over the last 19 years and that polar bears did not arrive on shore in 2009 until very late – approximately 22 August – the same date they came ashore in 1992.

Below are two figures from the paper: one (the map) necessary to understand the new “Cherry method” of calculating breakup dates for Hudson Bay (no disrespect intended) and the other (the graph), which presents the data collected. The table with my converted breakup dates is below them. A few quotes from the study and some comments on it follows.

UPDATE (March 21 2013; 6:12 PM PST). A typo in the table has been fixed (2001 is Jun 21 not Jul 21) and the post amended accordingly.
UPDATE 2 (July 7, 2013) The Cherry et al. paper is now in print, the references have been updated accordingly.

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