Warning over hungry grizzly bears
Yellowstone's grizzly bears are going to be particularly hungry this autumn - and that means more dangerous meetings with humans in a year that is already the area's deadliest on record.
Scientists report that a favourite food of many bears, nuts from whitebark pine cones, are scarce. So as grizzlies look to put on some major pounds in preparation for the long winter ahead they will be looking for another source of protein - meat - and running into trouble along the way.
Wildlife managers already report bears coming down off the mountains and into areas frequented by hunters, berry pickers and hikers.
"Pack your bear spray: there's going to be run-ins," said grizzly researcher Chuck Schwartz with the US Geological Survey.
Two people have been fatally mauled by grizzlies so far this year in Wyoming and Montana. Experts said that's the most in one year in at least a century for the Yellowstone region, which also includes parts of Idaho. The bears in both instances were later killed.
Full-grown Yellowstone bears can stand 6 feet tall and top 600 pounds. They have been known to peel off a man's face with a single swipe of their massive, clawed paws.
In the latest attack, a Michigan man was killed and two others injured when an undernourished bear and her three cubs marauded through a crowded campsite near Cooke City, Mont. on July 28. A month earlier, a botanist was killed by a bear shortly after the animal woke up from being tranquilised by researchers.
Yellowstone's grizzlies were recently placed back onto the threatened species list by a federal judge who cited in part a decline in whitebark pine.
Beetles, apparently surviving winters in larger numbers due to less frequently freezing temperatures, have decimated vast stands of the high-altitude trees. In some areas studied by researchers, more than 70 per cent of trees have been destroyed.
The attacks highlighted the hazards of a region that is home to an estimated 580 grizzlies and visited by more than 3 million people a year. And officials said the maulings should serve as a warning as bears begin to push to lower elevations. Adult males will need to gain on average 50 pounds (22 kilograms) in the next few months to last through the winter.