A lecture on the Grizzly Bear featured several "experts" on Bear behavior.

The first said that the Grizzly only attacks if suprized and a hiker should tie jingle bells to his pack frame so the bear can hear him coming and avoid confrontation.

The second "expert" said that firearms are unnecessary and a Hiker should carry only pepper spray to ward off an attacking bear.

The third fellow to speak was a professional guide and hunter. He said that its important to know what sort of bears are in the area you plan to hike in. You can tell by examining the droppings he said.
The Black Bear is a herbivore and seldom eats meat, his droppings contain undigested seeds and other plant material, plus the occasional scrap of fur from squirrels or other small animals. The dropping smell like rotting vegetation.
The Brown bear is more ominivorus and will eat meat if the opportunity presents itself, so besides plant materials there will be undigested bits of bone from fish and animals like deer. The dropping smell of vegetable matter and decayed meat.
The Grizzly eats meat as often as it can, its droppings contain relatively little vegetable matter and often will contain little tiny bells and smell like pepper.