My Grandparents camped in Yosemite in the 1930s with my Mom and her four brothers and sisters. Even back then the bears knew what the campers had to offer in the campgrounds. My Grandfather would tie about 10 feet of fishing line to a piece of bacon, and the other end to a bunch of empty tin cans. The story has been passed down in the family, that you could hear the bear being chased by the tin cans for quite a while. You may wake up the neighbors if you tried that now.