National Geographic : 1976 Jul
ATURALIST JOHN MUIR once said of the grizzly that "to him almost every thing is food except granite." In fact, the bears are rather selective eaters, but they have a varied menu. Grizzlies, like the two mothers and their cubs on a foraging trip in Yellowstone National Park (above), are omnivorous; plants comprise between 70 and 80 percent of their diet. Our research has revealed the basic components of grizzly bear habitat. His living space must contain huckleberries, whitebark pine nuts (right), small rodents, and big game. These foods tend to fluctuate in abundance from year to year, however. If both pine nuts and berries are scarce during one season, the grizzly is lean and hungry and must rely on grasses, sedges, and plant tubers to carry him through. He often dines on the succulent leaves and starchy roots of the bigroot spring beauty (far right, upper) or the bulbs of Melica spectabilis (far right, lower), a moun tain grass. Animals on his menu include an occasional elk, such small mammals as the rabbit-related pika (left), the ground squirrel, and the pocket gopher, plus carrion and fish. With this type of knowledge of the grizzly's eating habits, and aided by the National Geo graphic Society, the National Aeronautics and Space Administration, the U. S. Fish and Wildlife Service, and the U. S. Forest Service, we set out to map the grizzly's larder.