If I'm hiking, I almost always carry one of my 1911 pistols in .45, but if I get into bear country, I always carry my .454 Casull. Mountain lions are soft skinned, and anything from a hot 9mm on up should work fine, the bigger the better. Bears require a .357 Mag or 10mm at the least, and preferably a .44 Mag or better if available. We're talking black bear country here. If you're in grizzly county, a hot .44 Mag or better backing up a sizable rifle is the way to go.
I don't think it's nice,...you laughing.
You see, my mule don't like people laughing.
He gets the crazy idea you're laughing at him.
Now if you apologize, like I know you're going to,
I might convince him that you really didn't mean it.