Monthly Archives: November 2023

Polar bear sea ice habitat update at 15 November & problem bears in Western Hudson Bay

Abundant polar bear habitat this fall across the Arctic so far, with only Hudson Bay sea ice formation a bit behind schedule. However, Churchill has not seen the anticipated spike in problem bear reports, given the vocal pronouncement by polar bear specialists that it should be experiencing more and more problems with bears when they spent more than 4 months ashore in summer and fall.

News of the most egregious attack by a bear I could find world wide this fall is shown in the video below, filmed 14 November 2023: apparently, the offending bear had spent several days displaying this offending behaviour.

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Walrus and polar bear population size changes in the N. Atlantic over the last 20k years

This is a lesson in how to assess the potential worth of scientific papers. One of two similar Arctic evolution studies got media attention, at least in Canada — about the polar bears, of course — but in my opinion the walrus research conclusions are much better supported, less biased by climate change rhetoric, and lack the hubris present in the polar bear paper.

Both studies use similar sample sizes for the regions they had in common (North Atlantic) and used computer models to determine genetic diversity and population size changes since the LGM. However, the tone of the walrus paper was less emotionally-charged and the caveats of the work were appropriately stated. In my opinion, papers like the polar bear example contribute to eroding the public’s trust in science.

The last Ice Age peaked between about 27,000 and 19,000 years ago. At this time the Arctic was buried under kilometers of glacial ice sheets, and so marine mammals were pushed southwards to areas of ice floes and more open water. Walrus survived in some areas of the Atlantic located further to the south, and as soon as climates warmed again, the ice edge retreated and walrus populations pushed quickly northwards again. This combination of warming and climate-driven dispersal led to local walrus populations becoming more genetically differentiated. Walrus study, Lund University press release 27 September 2023

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Polar Bear Evolution pre-Christmas book sale: discounts on all formats!

I have reduced prices on all formats of my Polar Bear Evolution book for four weeks starting today (8 November-6 December 2023), in time for holiday gift-giving. The ebook version has the largest price reduction (60% of regular price, to US$17.40) but the other discounts are also substantial. This sale is a time limited offer: don’t miss out! Links below.

This is the book for those who are really interested in how grizzly bears could have turned into polar bears and why the story of polar bear evolution could not be told without discussing climate change.

One Amazon reviewer said this about Polar Bear Evolution:

The author of Polar Bear Evolution, Susan Crockford, is a good, credentialed scientist. Her writing is clear; her thinking is also. She has a broad understanding of biology and an informed paleo perspective. Crockford condenses a very large literature on polar bear biology and evolution in this book which will help readers understand the science related to the evolution of an Arctic species. Perhaps the most important aspect of this book is its synthesis of information from the fields of wildlife biology, molecular evolution, paleontology, and climate. Her original ideas and hypotheses on thyroid hormone’s role in evolution are very important and add a credible mechanism of phenotypic change which complements the literature on molecular genetic evolution. Polar Bear Evolution is an important contribution to science and its application in evolutionary biology and wildlife biology. Matthew A. Cronin, Ph.D.

Available at the links below (others also available):



Canada [shipping delay for hardcover version is 4-5 weeks]