See the bear before you surprise it. Watch for bear sign such as tracks, scat, and feeding sites (diggings, rolled rocks, torn up logs, ripped open ant hills).
Avoid Hiking at Dawn, Dusk, or at Night
Whenever possible avoid hiking at dawn, dusk, or at night. During the hot summer season these are the periods when grizzly bears are most active.
Hike Close Together or in Groups
Whenever possible hike in groups of three or more people—91% of the people injured by bears in Yellowstone since 1970 were hiking alone or with only one hiking partner, only 9% of the people injured by bears were in groups of three or more people.
Don't Expect Bears to Notice You First
In Yellowstone National park bears hibernate for approximately 5 months each year and have only 7 months of active time to obtain all of their nutritional needs. Therefore a bear with its head down feeding may not see you as you as quickly as you would think. Pay attention and see the bear before it sees you and before you surprise it.
Make Noise, Alert Bears to Your Presence
When hiking, periodically yell "Hey Bear" especially when walking through dense vegetation or blind spots, or when traveling upwind, near loud streams, or on windy days. Avoid thick brush whenever possible.
Ungulate carcasses are a highly preferred bear food that bears will guard and defend against other scavengers or humans. Dead ungulates will attract and hold many bears near the carcass site. It is risky to approach a carcass; many bears may be bedded nearby just out of sight. If you find a fresh dead ungulate carcass that still has a lot of meat remaining, leave the immediate area by the same route you approached the carcass from. If you walked to the carcass without encountering a bear you should be able to back out the same way without surprising a bear. Report all carcasses to the nearest ranger station or visitor center.
Stay With Your Gear
Don't leave your packs, lunches, food, or beverages unattended as they may attract and hold bears at the site. If you surprise a bear that's eating your stashed food you may lose
more than your lunch.
When hiking, stay alert and aware of your surroundings. Frequently look ahead, off to the sides, and behind you. See the bear before you surprise it!