BILLINGS, Mont. - A government-sponsored research team has concluded there are no signs of decline among Yellowstone's grizzly bears as officials consider lifting the animals' federal protections - despite warnings from outside scientists that such a move would be premature.
Members of the Interagency Grizzly Bear Study team say in a new study that data collected on the threatened bruins over the past several decades contradict claims that the animals could be in serious trouble.
Researchers on the team re-examined how bears are counted after wildlife advocates and a prominent University of Colorado professor questioned the government's methods.
The results confirm the validity of past assertions that more than 700 bears live in the Yellowstone region of Montana, Idaho and Wyoming, lead author Frank van Manen said. The peer-reviewed study is slated to appear in an upcoming issue of the scientific journal Conservation Letters.
"The (grizzly bear) population growth has slowed down in the last decade, but is by all means a robust population right now," van Manen said. "Critiques in scientific efforts can be constructive. Because of this critique, we looked very hard at our own data ... It basically confirms what we had seen before."
U.S. Fish and Wildlife Service officials are expected to soon announce whether grizzly bears should lose their threatened species. That would kick off a yearlong rulemaking process prior to a final decision in 2015.
Rising numbers of bear-human conflicts -- including periodic maulings of hunters, hikers and others -- have lent new urgency to calls to lift their legal protections and allow limited hunting of grizzlies to resume. Hunters and trappers exterminated the animals across most of the Lower 48 states during the last century.
Yellowstone's bears lost federal protections once, in 2007, until a federal judge ordered them back onto the threatened species list two years later. Judge Donald Molloy cited concerns that a key food for some bears, the nuts from white bark pine trees, has grown increasingly scarce as insects kill large stands of the trees.
University of Colorado biologist Dan Doak said in a study last year that the loss of whitebark pine and a decline in another food source, cutthroat trout, may have pushed bears into areas where they are more likely to be seen during aerial surveys.
He said that doesn't necessarily mean there are more bears, only that more are being seen.
Doak and co-author Kerry Cutler also said wildlife officials mistakenly assumed female grizzly bears reproduce throughout a 30-year lifespan, compounding the government's overly-optimistic population estimates.
Doak said Thursday that he stood by his prior conclusions and hoped they would be further considered by the government study team as it sets up a monitoring program to keep track of bears after federal protections are lifted.
Van Manen said the study team's aerial surveys are corroborated by other factors. That includes a doubling of the area occupied by grizzlies since the 1970s and a trapping program that consistently identifies new bears.
Yellowstone's grizzly population is the second largest in the Lower 48, behind an estimated 1,000 bears in the Northern Continental Divide region that includes Glacier National Park. Smaller populations live in the Cabinet-Yaak, North Cascades and Selkirk areas of Idaho, Montana and Washington state.