Reports of bears foraging through garbage left by humans and other close encounters seem to be increasing. The four-legged animals have broken into homes and have been seen rambling through developed areas. Are they just being bears or have they mastered how to find food among humans? Scientists have researched the classic debate over "nature" and "nurture" among black bears for decades, from Yosemite National Park in the Sierra to central Florida and the Adirondacks in upstate New York.
A look at some recent encounters between bears and humans:
A woman was mauled when she and another employee of an Alaska backcountry lodge startled an adult grizzly bear while running on a trail in the Kenai Peninsula in August. In July, two employees of the Kodiak National Wildlife Refuge killed a Kodiak brown bear as it charged them. A pair of cubs ran off after the sow was shot.
Authorities gave up on a search in December for a black bear that caused a stir when it was spotted running through an alfalfa field in Mesa on the edge of metropolitan Phoenix. Bears are sighted in the area only about once every two years. TV news cameras captured video of the animal running across rows of green fields.
A homeowner could face charges after shooting two bear cubs rummaging through his trash southwest of Denver this month. One cub was killed instantly in Evergreen. The other was wounded and euthanized.
In August, a 67-year-old man fought off a black bear that attacked him on his porch in a foothill community west of Yosemite National Park. The man was bitten and scratched but drove himself to the hospital. Investigators found bags of trash ripped open near the man's door in Midpines.
State wildlife officials shot and killed two bears in September and trails were closed in the Sessions Woods Wildlife Management Area in Burlington. One bear had closely followed and nuzzled the leg of a female hiker on Aug. 28. The other charged state officials investigating the initial incident.
A Florida woman was bitten by a bear while walking her dog in the Orlando suburb of Lake Mary in December. The dog spotted the bear and tried to charge it. The woman fell and the bear bit her arm and leg. About nine months earlier, another Lake Mary woman was injured when a bear mauled her. Three people were later charged with misdemeanors for feeding bears.
On Aug. 31, an archery hunter pursuing elk was attacked by a grizzly bear with three cubs about 15 miles west of Yellowstone National Park. The bear chewed his arm, but the hunter was treated and released from a hospital. Also in August, authorities euthanized a 25-year-old grizzly in the same vicinity after it repeatedly broke into buildings in the Island Park area. On Wednesday, officials euthanized a black bear believed to have bitten a sleeping wildland firefighter.
A roving black bear spent more than a week in a central Louisiana neighborhood in May. The young bear got caught in a trap set by state biologists near the Spring Bayou Wildlife Management Area on the outskirts of Marksville, but it managed to open the door and escape.
Two grizzly bears were captured close to where a seasonal employee of Yellowstone National Park was killed in August in an area known as Lake Village. It was the sixth time since 2010 that someone has been killed by grizzlies in the greater Yellowstone area. State wildlife officials euthanized a female black bear that broke into at least one home on the edge of Billings in early September.
State wildlife officials euthanized two bears in the span of a week in late August at Lake Tahoe, bringing to five the number that have been killed in the region this year because they posed a danger and had lost their fear of humans. One, an 18-month-old female trapped in the mountains above Tahoe's south shore, had broken into two different homes in search of food and had been trapped before.
In January, a deer hunter in a tree stand fatally shot a black bear that began climbing up the tree toward him near the Spruce Run Recreation Area outside Union Township. The hunter shouted at the bear, hoping to scare it away, but finally shot the nearly 100-pound animal when it was 3 feet away.
A zoo in South Dakota is taking in two black bears that have caused trouble this summer at Grand Teton National Park in Wyoming. The Great Plains Zoo and Delbridge Museum of Natural History in Sioux Falls will be the new home to a cub and its 12-year-old mother, which has a history of raiding backpacks and campsites for food.