Bears don't like surprises. That's why most bear attacks happen when people have accidentally surprised a bear [source: Smith]. One way to keep this from happening is to make noise, and some hikers use bear bells to do that.
Bear bells are small metal bells like sleigh bells. Hikers tie single bear bells or clusters of bells to their boots, backpacks or walking sticks. The idea is that -- since the bells don't sound like any natural forest noise, and since bears almost always want to avoid people -- the bear bells will keep the bears away.
Many hikers swear by bear bells as a good way to keep from accidentally running into bears. However, research on bear bells is not conclusive. A study in Alaska found that hikers who used bear bells lowered their risk of grizzly bear charges [source: Jope]. Scientist Tom Smith of the U.S. Geological Survey's Alaska Science Center noticed that grizzly bears turned around and looked when he snapped a pencil to imitate twigs breaking or made a huffing noise similar to what bears make, but they did not react at all to the sound of bear bells [source: Manning]. Noted bear expert Stephen Herrero thinks it's possible that curious bears may actually be attracted to bear bells, and people have reported that loud, abrupt noises like the sounds of boat horns or small gas canister horns seem to work better for keeping bears away [source: Herrero].
The bottom line that everyone can agree on is that it's a good idea to make noise to avoid surprising a bear, especially when visibility is bad. Some people wear bear bells, while others blow horns or whistles, clap, shout "hey bear," or make other loud noises at regular intervals. Herrero prefers to yodel.
What about when you're at your campsite, minding your own business? There are ways to deter bears from approaching you there, too. Keep reading to learn about electric bear fences.