During the past decade, U.S. Fish & Wildlife Service Grizzly Bear Recovery Coordinator Chris Servheen says an average of 19 grizzly bears a year have been killed in the Northern Continental Divide Ecosystem, which currently has population of 900 grizzlies.
During the same time, an average of 29 grizzly bears a year have been killed in the Yellowstone region, which now has an estimated population of about 600 grizzlies.
Even more alarming, an average of 39 grizzlies a year perished in Yellowstone from 2007 to 2011. From 2002 to 2006, the average was 19 grizzlies a year.
The grizzly population for the Northern Continental Divide Ecosystem grew from 765 in 2004 to 900 today. The grizzly population for the Yellowstone region grew from 523 in 2004 to 600 today.
Why isYellowstone now averaging twice as many grizzly deaths when the region has a substantially smaller grizzly population than the Northern Continental Divide Ecosystem?
The main problem appears to be that Yellowstone's grizzlies used to feed heavily on high-fat, high-protien whitebark pine seeds, but a massive die-off of whitebark pine trees began around 2002. The Interagency Grizzly Bear Study Team has been monitoring stands of whitebark pine since 2002. The Study Team's annual report for 2010 says, "Total mortality on transect trees read since 2002 is 72.6% and 94.7 of transects contain beetle-killed trees."
The report goes on to say, "Near exclusive use of whitebark pine seeds by grizzly bears has been associated with falls in which mean cone production on transects exceeds 20 cones/tree. Typically, numbers of grizzly bear-human conflicts and management actions tend to increase during years with poor cone availibility."
With 72.6% of whitebark pine trees dead, every year is a poor cone year.
In 2010, there were a record high 50 grizzly bear deaths in the Yellowstone region. In addition, there were a record high 295 bear-human conflicts.
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