There's a joke that goes like this:

A local tells some hikers that they should wear bear bells, to scare bears away, but it's also important to check bear scat when you come across it, to tell if it's black bears around or grizzlies.
"Well," ask the hikers, "How do you tell the difference?"

"Oh, that's easy," says the local, "If it's grizzly scat, it'll have bells in it."