They advise park visitors to wear little bells on their clothes so they make noise when hiking. The bell noise allows bears to hear them coming from a distance and not be startled by a hiker accidentally sneaking up on them.
This might cause a bear to charge.
Visitors should also carry a pepper spray can just in case a bear is encountered. Spraying the pepper into the air will irritate the bear's sensitive nose and it will run away.
It is also a good idea to keep an eye out for fresh bear scat so you have an idea if bears are in the area. People should be able to recognize the difference between black bear and grizzley bear scat.
Black bear droppings are smaller and often contain berries, leaves, and possibly bits of fur.
Grizzley bear droppings tend to contain small bells and smell of pepper.
Bells might work to warn a bear.
The bells will not work if the bear is hungry. The bells will just make you an easier meal.
Remember the little brass bells in the bear scat joke ?
"That is how you know that you are in bear country," said the farmer to the city girl.
I've hiked at Glacier a couple times. We did see a grizz at a distance trying his hand at hunting Elk. What I noticed is you can smell bear, it's very strong, and have you ever noticed that someone staring at you without your knowledge can give you the heebie-jeebies? Bears too, but it's different.
I'd rather spray lead.