CASPER, Wyo. -- The estimated number of grizzly bears in the greater Yellowstone ecosystem increased this year to 618, said Mark Bruscino, the Wyoming Game and Fish Department's large carnivore section supervisor.
The number is only a preliminary estimate, but shows a stable or increasing number of bears in the area that encompasses most of northwest Wyoming and portions of Idaho and Montana, Bruscino said.
In 2011, officials estimated 593 grizzly bears lived in the ecosystem, according to Mark Haroldson, a supervisory wildlife biologist with the Interagency Grizzly Bear Study Team.
"We continue to see an increase in bear distribution, and all factors point towards the fact that the population is doing well," Bruscino said.
This year has also had among the highest numbers of grizzly bear deaths. As of Monday, officials have confirmed that 50 grizzly bears died in the greater Yellowstone ecosystem. Deaths range from those killed by officials because of repeated livestock depredation to natural causes.
Officials recorded 44 deaths in 2011, 50 in 2010 and 31 in 2009, according to data reported by the Interagency Grizzly Bear Study Team.
Grizzly bear deaths have increased because the bears' population has grown and because they are expanding their range, Bruscino said. As bears move into new areas with more humans, potential for conflict increases.
The deaths should not have an impact on the overall grizzly bear population, amounting to about 8 percent of the estimated minimum population. Grizzly bear experts say that number is sustainable, Bruscino said.
Officials are investigating six Wyoming grizzly bear deaths caused by humans since the beginning of September.
The deaths coincided with the beginning of the fall hunting season in the area, Bruscino said, and were not related to grizzly bear management.
Three of the adults killed had cubs. The five cubs were still alive but recorded as individual deaths because their survival is not guaranteed. The department will not release more information because the deaths are ongoing investigations, Bruscino said.
Six grizzly bears killed by humans is not an unusually high number for this time of year, Bruscino said.
Five adult bears were killed by humans in Wyoming during the fall 2011, with three cubs left behind, Bruscino said. Humans killed 14 adult bears in the fall of 2010, with four cubs left behind, and killed eight bears with seven cubs during the same period in 2009.
Grizzly bears are a protected species under the Endangered Species Act and it is illegal to hunt them. A federal appeals court announced in 2011 that before grizzly bears could be removed from the endangered species list, more work is needed to be done documenting how the decline in whitebark pine could affect grizzly populations.