In this part of my critique of Stirling and Parkinson (2006), regarding breakup dates in Western Hudson Bay (see Part I here), I will show that these authors also left out critical data.
Figure 1. A bear is transported to Churchill’s polar bear holding facility, from a 2011 Huffington Post article “Polar Bear Prison.”
Their correlation between number of problem bears in Churchill and breakup dates for WHB worked because some very inconvenient data were simply left out: problem bear data for 1983 and 2004.
Inclusion of that information would have shown 1983 and 2004 were two of the worst years for polar bear problems in recent history despite being late breakup years (1983 also had the last human fatality from a polar bear attack). They could have explained why they did not use the data but they did not — they simply left it out.
Amazingly, this work is being touted as “evidence” that global warming is harming Western Hudson Bay polar bears.
Posted in Advocacy, Polar bear attacks, Sea ice habitat
Tagged breakup, cherry-picking, Churchill, correlation, Derocher, early breakup, fatal attack, freeze-up, Kearney, less than healthy science, Ockham's Broom, Parkinson, polar bear, problem bears, Stirling, Towns, western hudson bay
The oft-repeated claim that polar bears are starving in Western Hudson Bay (e.g., here, here, here, and here) comes primarily from a 10 year old study that documented a declining trend in polar bear body condition (a biology euphemism for relative fatness) between 1980 and 2004, which appeared to correlate with earlier and earlier breakup dates for Hudson Bay.
Figure 1. Polar bear female with cub, 2009, Churchill, Western Hudson Bay. Wikipedia.
The authors of that study (polar bear specialist Ian Stirling and NASA sea ice researcher Claire Parkinson) reported the body weights of lone female bears captured in Western Hudson Bay between 1980 and 2004. The trend over time in those bear weights was then correlated with the overall change in dates of sea ice breakup on Hudson Bay for that period.
However, it turns out that while the trend of body condition and the trend in breakup dates indeed correlated over time, the actual year to year data did not. The question is, what does that mean for the claim that polar bears in WHB are starving?
Posted in Life History, Sea ice habitat
Tagged body condition, breakup, Cherry, climate change, Parkinson, pregnancy, sea ice, starving polar bears, Stirling, too thin, trends, weight, western hudson bay