Yellowstone grizzlies were placed under the Endangered Species Act in 1975 to protect their dwindling population. However, in recent years, it has become evident that the number of grizzly bears in Yellowstone National Park has increased considerably, Associated Press reported.
A new study conducted through the collaborative participation of the University of Montana, U.S. Geological Survey, Wildlife Genetics International and the Interagency Grizzly Bear Study Team found a four-fold increase in the population of Yellowstone grizzlies within a 25-year period. The study found that there has been an "independent demographic evidence for Yellowstone grizzly bear population growth since the 1980s."
"We already knew the grizzly bear population had been growing since the mid 1980s from our demographic analyses," team leader and USGS wildlife biologist Frank van Manen told Discovery News. "This study demonstrated that, in parallel with demographic growth, the effective population size (i.e. the number of individuals contributing genes to the next generation) increased as well."
Some experts said the bears have become too numerous and are reaching areas where their encounter with humans poses danger. The scarcity of their natural food sources is also driving them to go after human food sources. This year alone, 24 Yellowstone grizzlies were euthanized - the largest number in the last five years - because of the threat they posed to human life.
"Grizzly bears are moving into areas outside the recovery zone," van Manen told Associated Press. "They are getting into more and more of those areas where the potential for conflicts are greater."
The National Wildlife Federation agrees that delisting is the best route for Yellowstone grizzlies, because the Endangered Species Act has achieved its goal in helping the bear species recover. The agency clarified that the protection for the bears will not cease once they are delisted.
"The Endangered Species Act is intended to lead to recovery and delisting, so long as adequate plans exist to assure recovery continues," the National Wildlife Federation said in a statement. "Over a decade of work has gone into creating a conservation package for Yellowstone's grizzlies to ensure that the bears continue to thrive once taken of the list."
The study was published in the online Oct. 28 issue of the journal Molecular Ecology.
