Aug. 18, 2013 -- At least six people have been mauled in a spate of bear attacks in five states over the last week, raising questions about why there have been so many incidents this year.
On Saturday a hunter in the northern Alaskan wilderness was the latest person to be injured in a bear attack. The hunter had to be saved by helicopter after he was mauled by a brown bear and suffered severe blood loss.
The attacks on hunters and hikers come just before the start of hibernation season, as hungry bears search for food before settling in for winter. But the number of bear attacks is up across the country. In Yellowstone alone, there have been 64 percent more attacks so far this year than there were last year.
The first bear attack happened in Yellowstone National Park in Wyoming on Thursday. After grizzly cubs wandered close to a group of four hikers, the mother grizzly bear charged at the group. Two of the hikers were attacked by the bear. One of the men was clawed and bitten on his backside.
The grizzly bear and her cubs were scared off after the other two unharmed hikers deployed bear spray.
"This bear by all accounts was acting on instinct, defending its cub. That is natural and normal behavior for a sow grizzly," park spokesman Al Nash told The Associated Press.
The injured hiker was treated for his injuries and released. The attack was the first bear attack of the year in the park.
Yellowstone regulations require all visitors to stay 100 yards from any grizzly or black bear. Hikers are encouraged to travel in groups of three or more, make noise on the trail and carry bear spray.
In 2011, two hikers were killed in two seperate grizzly bear attacks in Yellowstone.
Less than an hour after that inital attack, two habitat researchers in Idaho were attacked by a grizzly bear that they had unknowingly awoken.
The bear attacked one of the men before his partner could use bear spray, Gregg Losinski of Idaho Fish and Game told ABC News. When the unharmed man pulled out the bear spray, the grizzly bear attacked his hands.
Eventually the men were able to get away from the bear and seek medical attention at the Madison Memorial Hospital in Rexburg, Idaho.
"The biggest worry is infection, as bears do not have clean teeth," Losinski said. The men suffered treatable but substantial injuries.
But in addition to these attacks that occurred deep in the wilderness, a 12-year-old girl was attacked near her home in Cadillac, Mich., on Thursday.
Abby Wetherell was jogging on a trail in her neighborhood when she was attacked by a black bear. She tried to run away but the bear caught up with her. According to her grandfather Dave Wetherall, Abbey played dead and then screamed for help.
"We're very proud of the way she handled herself," her grandfather, David Wetherell, told the AP. "She's kind of amazed us."
Abbey's father and a neighbor came to her aid after she screamed, and they found her with gashes on her leg. The bear had already run back into the woods.
The 12-year-old was taken to Munson Medical Center and was in good condition according to ABCNews.com affiliate WZZM-TV.
According to the Michigan Department of Natural Resources, the state has an estimated black bear population of 8,000 to 10,000, with 90 percent located in northern Michigan, where Cadillac is located.
However, black bear attacks on humans are highly unusual and occur mainly when a bear feels her cubs are threatened, according to the Department of Natural Resources. People who are attacked by black bears are encouraged to stand their ground and not back away or play dead.
The Michigan Department of Natural Resources is actively searching for the black bear that attacked Abby by setting bear traps and has plans to euthanize the bear after it is caught.
In spite of the attack, Dave Wetherall told WZZM-TV his granddaughter wasn't afraid of getting back on the trail.
"She's a hunter, she likes the woods, she's just a very tough, kind person," Wetherall said.
The Associated Press contributed to this article.