The first reply has a good definition of a predatory bear but talking nicely to one is not good enough.

You must fight a predatory bear and play dead only for a female protecting her cubs. Learn to recognize them.

A bear just looking at you just wants to know what you are. Talk to it nicely and leave.

My favorite video : Staying Safe in Bear Country.

While hiking, you want to let bears know that you are coming and they usually leave before you see them.

''Bear bells'' are useless, I tried. Tests were done and talking, whistling, claping hands, and signing will work better.