As human habitats expand into ever smaller wildlife areas, the coexistence of creatures great and small can be thrown out of balance - even become dangerous.
For instance, when people and bears end up in close quarters, the result can be a close encounter of the worst kind.
These days in a place like Lake Tahoe, it's not hard to find a 400-pound black bear sacking out for winter.
According to bear watcher Ann Bryant, bears are becoming so comfortable around people that this winter, about half of them just invited themselves to stay over.
Some have developed a habit of taking cover and sleeping under houses, while others have skipped hibernation altogether and porked out to double their normal sizes.
"They find garbage and some people put food out for them. They see a bear in winter and say 'Oh the poor bear looks hungry,' and leave a bowl of food out," says Bryant.
Black bears living in the Lake Tahoe area used to cover up to one 100 miles of rugged terrain looking for food, but since they have discovered urban living there is little reason to leave town, a circumstance that has given Lake Tahoe the second highest bear density in the nation, reports CBS News Correspondent Sandra Hughes.
Bear-proofing garbage cans is one way to stop so-called "dumpster-diving," but so many bears are dependent on human food that some are forgetting how to forage for food and have begun breaking into houses.
Caretaker Gena Ruschmeyer says a bear broke into her refrigerator and made a mess with a can of beer. "We ended up with glue made out of flour and beer," she says.
Celebrities have been seen cuddling up to bears lately, such as in a recent Animal Planet special featuring Jennifer Aniston.
Experts say when celebrities are shown cuddling up to bears, it reinforces the idea that bears and people belong together.
Nevada Fish and Wildlife Officer Carl Lakey knows they don't.
"The chances of serious conflict between bear and person is increasing the more the bears hang around this area," he says.
When bears wander into human terrain, Lakey shoots at them using rubber bullets trying to re-teach the bears to fear humans so he doesn't have to resort to real bullets.
Bears were killed in a similar incident in New Jersey, where for the first time in 33 years bear hunting licenses were given to just about anyone willing to kill a bear.
That event was heartbreaking for Bryant, who says it's not just the bears who need re-training.
"We have had people who have painted peanut butter on kids faces so the bear will come up and lick the peanut butter off the child's face and get a picture of it," says Bryant.
Between the curious and the concerned, it's humans who have caused this showdown, but it's the bears who almost always end up the losers.
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