Large margins of error in polar bear population estimates means the conservation status threshold of a 30% decline (real or predicted) used by the US Endangered Species Act and the IUCN Red List is probably not valid for this species.
Several recent subpopulation estimates have shown an increase between one estimate and another of greater than 30% yet deemed not to be statistacally significant due to large margins of error. How can such estimates be used to assess whether population numbers have declined enough to warrant IUCN Red List or ESA protection?
What do polar bear population numbers mean for conservation status, if anything?
Posted in Conservation Status, Population
Tagged baffin bay, declining, Derocher, errors, ESA, estimate, facts, IUCN Red List, numbers, polar bear, population, science, significance, statistics, Svalbard, western hudson bay
Polar bear specialist Mitch Taylor emailed me and others his response to the New York Times article that appeared Tuesday (10 April) about the Harvey et al. (2018) BioScience paper attacking my scientific integrity. Here it is in full, with his permission, and my comments. Don’t miss the footnote!
Posted in Advocacy, Conservation Status, Population, Scientists hit back
Tagged accountability, Amstrup, CO2, consensus, Derocher, fake news, fake science, IUCN, Mitch Taylor, PBSG, peer-review, polar bear, predictions, Red list, Regehr, science, sea ice
Polar bear specialists made global population numbers the focus of the world’s attention when they predicted a dramatic decline and possible extinction of the species. But now that the numbers have increased slightly rather than declined, the same scientists say global numbers are meaningless: the public should give those figures no credence and anyone who cites global population numbers should be mocked.
See the screen shot from a 2015 NBC news video above and another from the science journal NATURE in 2008 below (Courtland 2008):
Yet, below is a recent message from one of the world’s most vocal polar bear specialists, four years after a similar incident raised the public’s ire:
However, you can’t make a plausible prediction of future survival without an estimate of present population size: not even today’s worst journalists would buy it, nor should they.
Polar bear specialists Andrew Derocher and Steven Amstrup recently spent inordinate energy trying to refute the opinion piece I’d written for the Financial Post in celebration of International Polar Bear Day last month, ignoring my fully referenced State of the Polar Bear Report for 2017 that was released the same day (Crockford 2018) and the scientific manuscript I’d posted last year at PeerJ Preprints (Crockford 2017).
Their responses use misdirection and strawman arguments to make points. Such an approach would not work with the scientific community in a public review of my paper at PeerJ, but it’s perfect spin for the self-proclaimed “fact-checking” organization called Climate Feedback. The result is a wildly ineffective rebuttal of my scientific conclusion that Amstrup’s 2007 polar bear survival model has failed miserably.
This is Part 2 of my expose, see Part 1 here.
Posted in Conservation Status, Population, Sea ice habitat, Summary
Tagged Amstrup, bearded seal, Beaufort, Chukchi Sea, Climate Feedback, damage control, Derocher, ESA, fact checker, failed predictions, ice-free, observations, polar bear, predictions, ringed seal, sea ice, spin, spring, Stirling, summer, survival, thick ice, threatened
It’s been more than a year since I first published my scientific manuscript at PeerJ Preprints (a legitimate scientific forum) on the failure of Amstrup’s 2007 USGS polar bear survival model (Crockford 2017), a year waiting in vain for the polar bear community to comment. They either couldn’t be bothered or knew they couldn’t refute it – I haven’t known for sure which. But I do now.
Polar bear specialists didn’t comment because they couldn’t refute it in the scholarly manner required by PeerJ: all they could do is tear it down with derision, misdirection and strawman arguments.
I know this because the damage control team for the polar-bears-are-all-going-to-die-unless-we-stop-using-fossil-fuels message wasn’t activated over my fully-referenced State of the Polar Bear Report for 2017 (Crockford 2018) released on International Polar Bear Day last month, but for a widely-read opinion piece I’d written for the Financial Post published the same day (based on the Report) that generated three follow-up radio interviews.
By choosing to respond to my op-ed rather than the Report or my 2017 paper, biologists Andrew Derocher and Steven Amstrup, on behalf of their polar bear specialist colleagues1, display a perverse desire to control the public narrative rather than ensure sound science prevails. Their scientifically weak “analysis” of my op-ed (2 March 2018), published by Climate Feedback (self-proclaimed “fact checkers”), attempts damage control for their message and makes attacks on my integrity. However, a scientific refutation of the premise of my 2017 paper, or The State of the Polar Bear Report 2017, it is not (Crockford 2017, 2018).
Derocher further embarrasses himself by repeating the ridiculous claim that global polar bear population estimates were never meant for scientific use, then reiterates the message with added emphasis on twitter:
Just as the badly written Harvey et al. (2017) Bioscience paper said more about the naked desperation of the authors than it did about me or my fellow bloggers, this attempt by the polar bear community’s loudest bulldogs to discredit me and my work reveals their frustration at being unable to refute my scientifically supported conclusion that Amstrup’s 2007 polar bear survival model has failed miserably (Crockford 2017).
Part 1 of my detailed, fully referenced responses to their “analysis” of my op-ed are below. Part 2 to follow [here]. Continue reading
Posted in Conservation Status, Scientists hit back, Sea ice habitat, Summary
Tagged Amstrup, critique, damage control, Derocher, endangered, ESA, fact checker, facts, feedback, polar bear, predictions, sea ice, spin, State of the Polar Bear, threatened, USGS
A just-released report on the most recent (2016) survey shows Western Hudson Bay polar bear numbers were still stable despite predictions that this subpopulation would be wiped out completely (reduced to zero) due to low Arctic sea ice.
The authors of the report on the August 2016 aerial survey of the Western Hudson Bay polar bear subpopulation (Dyck et al. 2017) state clearly that the only trends they could find were that the number of adult males increased somewhat over 2011 estimates and the number of females either declined or remained stable. The overall population estimate was a bit lower (11% less) compared to the 2011 survey but the difference is not statistically significant. Therefore, the population status must be stable.
2011 estimate: 949 bears (using comparable data, range 618-1280), litter size 1.43
2016 estimate: 842 bears (using comparable data, range 562-1121), litter size 1.63
[cf. Foxe Basin [stable], from 2009-2010 survey (Stapleton et al. 2016) litter size was 1.54]
An 11% decline in WH numbers since 2011 is most definitely NOT the decline to ZERO (extirpation) we were told to expect with Arctic sea ice as low as it has been since 2007 (Crockford 2017, see list of annual minimum extents 2007-2017 here).
Note: The percentage decline from 2011 to 2016 for Western Hudson Bay polar bears is 11%, NOT 18% as claimed recently by Andrew Derocher on twitter: it is not appropriate to compare the official 2011 estimate of 1030 (Stapleton 2014) to the 2016 estimate of 842 because the methods used to generate the estimates were different (Dyck et al. 2017). The authors of the report state that the estimate for 2011 that’s comparable to 2016 is 949.
An 11% decline from 1030 would be 917 bears, a statistically insignificant decline that is also biologically insignificant and therefore, so slight as to indicate a stable population.
Predicted sea ice at 2050 and 2080 shown below (see Crockford 2017 for details):
Quotes, map, and table from the Dyck et al. 2017 report (pdf here) are copied below.
Posted in Conservation Status, Population, Sea ice habitat
Tagged decline, Derocher, estimate, extirpated, facts, increasing, polar bear, population, significant, size, slight, stable, statistics, status, survey, western hudson bay