Some campers were visiting a remote park, and encountered the Park Ranger as they entered.
He warned them about the bears.
He said there were black bears and grizzly bears in the park, and to watch out for them.
The campers didn't know how to tell one bear from another, so the Ranger explained that they could tell if there were black bears in the area by the droppings on the ground, which usually had berries in it.
He told them that they could use pepper spray to ward them off, if they had an encounter.
Then the campers asked, "How do we tell if grizzly bears are in the area?"
The ranger explained that there would probably be bear droppings on the ground from them too.
The campers inquired, "How can we recognize the grizzly bear droppings?"
The ranger replied, "Grizzly bear droppings have bone fragments in it, and usually smell like pepper spray".