Challenges to Government's Claim That Greater Yellowstone Ecosystem's Grizzly Population Is Well

Claims by the Interagency Grizzly Bear Study Team that the grizzly bear population in the Greater Yellowstone Ecosystem is growing and genetically diverse are off-base, according to a wildlife biologist who long has studied the population and spent 17 years doing research for the team. The analysis promoted by the IGBST a week ago shows that the bear population in the ecosystem has continued to grow since the 1980s. Results indicate that the effective population size of Yellowstone grizzly bears, or the number of individuals that contribute offspring to the next generation, has increased 4-fold over a 25-year period, the report maintained. This provides evidence that Yellowstone grizzly bears are approaching the effective size necessary for long-term genetic viability, the study said.  But Dr. Dave Mattson, who has studied bears for three decades, said the claims can't be supported. “For this to happen, population growth rates would have needed to exceed anything known, or even possible, for grizzly bears, and the resulting putative size of the population would be far in excess of even the most optimistic current estimates,” said Dr. Mattson in a release. Dr. Mattson maintains that the report was issued to support efforts in Wyoming, Idaho, and Montana to remove the grizzly bear from Endangered Species Act protection. On the Grizzly Times blog, writer Louisa Willcox, who long has followed wildlife issues in the ecosystem, argues that the recent upturn in the grizzly population is too small to declare success in recovering the species, particularly when you accept that there once were 100,000 grizzlies roaming the United States...more