Hikers in Yellowstone National Park will see new signs this summer warning them of bears and telling them what to do if they encounter one. The signs are simpler than the old ones, which have been used since the 1980s. The new signs provide basic suggestions like be alert, make noise, carry bear spray, avoid hiking alone and do not run. The words "bear attack" are in large font at the top of the signs to catch hikers' attention. Kerry Gunther, a Yellowstone bear management biologist, says the park recommends hiking in groups, carrying bear spray and not running if you surprise a bear. Two people were killed in the park in separate bear encounters last summer. Neither hiker carried bear spray. One ran when attacked and one was hiking alone.