From another thread...
"Black bears do this thing called a "bluff" where they charge at you making loud grunting noises. But have no fear, they stop just short of reach you. It's a warning. But they rarely go into a full blown attack; even mother bears will back off if you mess with her cubs. She will bluff and try to scare you off, but won't generally go in for a kill.
The bears who do attack people are usually those who have their territories infringed upon by human activity, and who (through experience with people) learn not to be afraid of people; so when they see people (at a camp site, or somewhere where garbage and food are left around) they may become territorial.
In reality, bears and people could live side by side quite well if there was more understanding and respect of bear activity. Instead, people tend to view bears as threats and have inaccurate perceptions of their behavior and temperament. They are the most intelligent species in north America, after humans."
