Monday, June 17, 2013

Global Warming? Now we have too many polar bears?

Via Daily Timewaster

Science can't decide whether population has stalled because of less ice or a surplus of bears.

Exciting news about polar bears in eastern Canada: A peer-reviewed paper on the Davis Strait subpopulation study has finally been published in the Journal of Wildlife Management. It concludes that despite sea ice having declined since the 1970s, polar bear numbers in Davis Strait have not only increased to a greater density (bears per 1,000 km2) than other seasonal-ice subpopulations (like Western Hudson Bay), but may now have reached its carrying capacity.

This is great news. But where is the shouting from the roof-tops? The study was published online in February and in print in April.  No press release was issued that I could find and, consequently, there was no news coverage.

Funny, that. There was a bit of shouting back in 2007 when the study ended and the preliminary population count was released. Mitch Taylor, a polar bear biologist at Lakehead University in Ontario, was quoted in the Telegraph: “There aren’t just a few more bears. There are a hell of a lot more bears.” There was also a CBC news item in January, 2007. But the story then focused only on preliminary information about population increase. The newly-published study — by Lily Peacock of the U.S. Geological Survey in Anchorage, and three other colleagues including Mr. Taylor of Lakehead University — reveals that the story in Davis Strait is about more than simple population growth.

The study compared data from mark-recapture studies done in 1974-1979 to those undertaken in 2005- 2007.  The authors state that in Davis Strait,  ”the overall amount of sea ice declined and breakup has become progressively earlier” since the 1970s. However, in spite of this decline in sea ice, they estimated the number of bears at about 2,158, a substantial increase over the estimate of about 1,400 bears in 1993.

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