They are also commonly observed in the northwest corner of the park. Black bears are more active during daytime. Look for black bears around the northern range of the park, Gunther says. They can often be observed near the road corridor from Mammoth east through Tower to the park's Northeast entrance. Black bears are also commonly observed near Old Faithful, Madison and Canyon areas, as well as near the Bechler region in the southwest corner of Yellowstone.
Grizzly bears feed on bison carcasses and elk calves, especially in the spring.
Their predation on elk calves continues until mid-summer. Gunther, who has been studying and working with the bears of Yellowstone since 1983, says one of his most memorable experiences while observing grizzlies was when he saw one chasing an elk calf at full speed. A large herd of elk was running from the grizzly, who eventually got the calf he wanted. Grizzlies also consume lots of grasses and sedges, dandelion, clover, spring-beauty, horestail, and ants. In areas around Yellowstone Lake, the grizzly feeds on spawning cutthroat trout.