Tag Archives: Lunn

Critical evidence on W Hudson Bay polar bears still not published after 25 years

Polar bear researchers have been doing capture/recapture studies in Western Hudson Bay for decades yet most of the data claimed to be critical for assessing effects of human-caused global warming on this species have not been published. I raised this point in one of my early blog posts (27 Sept 2012) but the situation has not changed in 6 years. Here’s an update.

Derocher in the field in WH_CBC story 2016

From CBC story 14 Sept 2016.

Years ago now, in an oft-cited paper, Stirling and Derocher (2012) claimed to summarize the evidence that climate warming was negatively impacting polar bear health and survival. Several life history parameters were considered crucial, particularly body condition.

Despite almost a dozen papers (and perhaps more) on various aspects of WH polar bear health and life history studies based on capture/recapture data published since 2004  (e.g. Castro de la Guardia 2017; Lunn et al. 2016; Pilfold et al. 2017), none have reported the body condition data that supposedly support the claim that sea ice loss is having a severe impact — and the same is true for litter size, proportion of independent yearlings, and cub survival.1

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No correlation between freeze-up dates for Hudson Bay & total Arctic ice cover

Guess which year between 2006 and 2016 had the latest start to freeze-up on Hudson Bay, given that 2012 had the lowest September average and 2007 and 2016 tied for second-lowest (see graph below, from NSIDC), and that sea ice in the Arctic right now is the lowest it’s been for this date since 1979?


If you guessed anything other than 2010, you guessed wrong – in addition, 2006 (not 2016) was second latest.

There is no correlation between Arctic sea ice coverage and freeze-up dates for Western Hudson Bay.

Yet, Polar Bears International (“Save Our Sea Ice”) –  who were surely in and around Churchill in 2010 and 2006 watching polar bears – just posted an alarming statement about local conditions, implying that slow freeze-up of Hudson Bay this year is a reflection of the fact that “sea ice is at a record low across the Arctic.”

They also claim that “…the weather is the warmest we’ve ever seen at this time of year.” That may be true, but if so, it is also meaningless with respect to the progress of freeze-up.

Does no one at PBI remember the very late freeze-up of 2010 or 2006? Odd, that.

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W. Hudson Bay polar bear numbers declined then stabilized, says new paper

Polarbear_Parks Canada Wapusk in August

Western Hudson Bay bear, Wakusp National Park, August 2011.

In the just-published version of their Western Hudson Bay (WHB) population survey conducted in 2011, Nick Lunn and colleagues highlighted in the abstract:

“Our analysis suggested a long-term decline in the number of bears from 1,185 (993-1411) in 1987 to 806 (653-984) in 2011…” 

But they didn’t mention that the 806 estimate for 2011 was based on only a portion of the WHB region (Fig. 1) and has not been accepted by their peers as a valid estimate of the population size. They also failed to mention that the decline occurred due to thick spring ice and/or unsuitable snow conditions for ringed seals between 1989 and 1992 (Fig. 2), which resulted in reduced availability of polar bear prey (as I discussed in detail in Crockford 2015).

They know the “long-term” population decline is what the media will grab onto and run with – rather than the next sentence, which says “In the last 10 years of the study, the number of bears appeared stable due to temporary stability in sea ice conditions.

In other words, their study shows there has been no decline in the population since 2004, which had been predicted to occur (see previous post, Prediction #1), and there has been no trend in either breakup or freeze-up dates between 2001 and 2010 (or since). See previous post on the government report on which this paper is based here.

The bottom line is this: no one is buying this population estimate of 806 bears for the Western Hudson Bay population – both the IUCN Polar Bear Specialist Group and Environment Canada are using Seth Stapleton and colleagues (2014) estimate from their aerial survey done the same year and that official population size number is 1030 bears. Continue reading

IUCN Red Book officials forced scientific standards on polar bear predictive models

As I reported Thursday, the IUCN announcement of a new Red List assessment for polar bear got the usual overwrought attention from international media outlets. However, not one of these contained a quote from a polar bear biologist.


Steven Amstrup, science spokesperson for activist conservation organization Polar Bears International, has so far had nothing to say to the media. Yet, Amstrup was a co-author of the IUCN Red List report. Not until late in the day following the release of the report did his his organization’s website post a short, bland news report (“Climate Change Still Primary Threat to Polar Bears”).

Similarly, Ian Stirling, Andrew Derocher, Nicholas Lunn (also a co-author of the IUCN Red List report), and former WWF employee Geoff York – who are usual go-to guys for polar-bears-are-all-going-to-die media frenzies – have so far been silent and invisible on this issue.

In addition, while the IUCN press release [backup here: 2015 IUCN Red List press release_Nov 19 2015] included a quote from IUCN Polar Bear Specialist Group (PBSG) chairman Dag Vongraven, as of this morning (21 November, PST), the website of the PBSG contains no mention of this decision – no item in the “News” category  and, more importantly, no update of the status table  or global estimates to reflect the changes contained in the report  (even though they obviously knew it was coming months ago: the report was submitted to the IUCN Red List 27 August 2015).

In my opinion, this silence says it all: polar bear specialists know this assessment is a severe de facto critique of their 2008 assessment (as well as Amstrup’s predictive models) and it’s a big step backwards for their conservation activism. I expect they are silent because they are royally pissed off.

However, this assessment is good news because finally, some standards of scientific rigor have been applied to polar bear predictive models – even though the PBSG were still been allowed to pretend that summer sea ice coverage is critical to polar bear health and survival (Crockford 2015).  Continue reading

BBC perspective on Arviat polar bears – those not included in the last mark-recapture study

In a polite but misleading article today in a BBC magazine (The polar bears are coming to town) about the relationship of polar bears and Inuit in Arviat, Western Hudson Bay, there is no mention of the on-going feud between Nunavut Inuit and Canadian polar bear scientists regarding invasive research.

Churchill_Polar_Bear_2004-11-15 Wikipedia

Nor is there a mention of the fact that according to the most recent research, there has been no trend in sea ice conditions since 2001.
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Western Hudson Bay polar bear numbers are stable, no trend in ice breakup or freeze-up

This needs saying again: the latest study on Western Hudson Bay polar bears reveal the population has been stable since 2004 and there has been no significant trend in either breakup or freeze-up dates since 2001.

Triplets in Wapusk NP from McCall webpage 2013

Environment Canada and the IUCN Polar Bear Specialist Group concur that the current size of the WHB subpopulation is about 1030 bears. Documents found online indicate a new version of the 2013 WHB mark-recapture report (Lunn et al. 2013) is now available (Lunn et al. 2014) and that a new population survey is planned for 2016. A 2013 story based on false information produced by The Guardian that is still in circulation should be retracted.
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Hudson Bay breakup progressing slowly, still lots of polar bear habitat

Not much change in sea ice coverage since last week – most of Hudson Bay is still covered with concentrated ice, which is good news for Western and Southern Hudson Bay polar bears. They are still free to roam and hunt over most of the ice-covered bay.

Hudson Bay breakup 8 June 2015 vs 1 June_PolarBearScience

There may be slightly less ice than average for this time of year (Fig. 1, below) but coverage is still >70% with concentrated ice and does not appear to be melting quickly (see charts above and Fig. 2, below).

The dates for three previous earliest breakups according to Lunn and colleagues (Fig. 3) have come and gone, as all were in the first week of June (more on that in an upcoming post) – no records broken. More graphs and maps below, see previous posts here and here.
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