<P> Meat, as already described, is an important part of a grizzly's diet . Grizzly bears occasionally prey on small mammals, such as marmots, ground squirrels, lemmings, and voles . The most famous example of such predation is in Denali National Park and Preserve, where grizzlies chase, pounce on, and dig up Arctic ground squirrels to eat . In some areas, grizzly bears prey on hoary marmots, overturning rocks to reach them, and in some cases preying on them when they are in hibernation . Larger prey includes bison and moose, which are sometimes taken by bears in Yellowstone National Park . Because bison and moose are dangerous prey, grizzlies usually use cover to stalk them and / or pick off weak individuals or calves . Grizzlies in Alaska also regularly prey on moose calves, which in Denali National Park may be their main source of meat . In fact, grizzly bears are such important predators of moose and elk calves in Alaska and in Yellowstone, that they may kill as many as 51 percent of elk or moose calves born that year . Grizzly bears have also been blamed in the decline of elk in Yellowstone National Park when the actual predators were thought to be gray wolves . In northern Alaska, grizzlies are a significant predator of caribou, mostly taking sick or old individuals or calves . Several studies show that grizzly bears may follow the caribou herds year - round in order to maintain their food supply . In northern Alaska, grizzly bears often encounter muskox . Despite the fact that muskox do not usually occur in grizzly habitat and that they are bigger and more powerful than caribou, predation on muskox by grizzlies has been recorded . </P> <P> Grizzly bears along the Alaskan coast also scavenge on dead or washed up whales . Usually such incidents involve only one or two grizzlies at a carcass, but up to ten large males have been seen at a time eating a dead humpback whale . Dead seals and sea lions are also consumed . </P> <P> Although the diets of grizzly bears vary extensively based on seasonal and regional changes, plants make up a large portion of them, with some estimates as high as 80--90% . Various berries constitute an important food source when they are available . These can include blueberries, blackberries (Rubus fruticosus), salmon berries (Rubus spectabilis), cranberries (Vaccinium oxycoccos), buffalo berries (Shepherdia argentea), soapberries (Shepherdia canadensis), and huckleberries (Vaccinium parvifolium), depending on the environment . Insects such as ladybugs, ants, and bees are eaten if they are available in large quantities . In Yellowstone National Park, grizzly bears may obtain half of their yearly caloric needs by feeding on miller moths that congregate on mountain slopes . When food is abundant, grizzly bears will feed in groups . For example, many grizzly bears will visit meadows right after an avalanche or glacier slide . This is due to an influx of legumes, such as Hedysarum, which the grizzlies consume in massive amounts . When food sources become scarcer, however, they separate once again . </P> <P> The removal of wolves and the grizzly bear in California may have greatly reduced the abundance of the endangered San Joaquin Kit Fox . With the reintroduction of gray wolves to Yellowstone, many visitors have witnessed a once common struggle between a keystone species, the grizzly bear, and its historic rival, the gray wolf . The interactions of grizzly bears with the wolves of Yellowstone have been under considerable study . Typically, the conflict will be in the defense of young or over a carcass, which is commonly an elk killed by wolves . The grizzly bear uses its keen sense of smell to locate the kill . As the wolves and grizzly compete for the kill, one wolf may try to distract the bear while the others feed . The bear then may retaliate by chasing the wolves . If the wolves become aggressive with the bear, it is normally in the form of quick nips at its hind legs . Thus, the bear will sit down and use its ability to protect itself in a full circle . Rarely do interactions such as these end in death or serious injury to either animal . One carcass simply is not usually worth the risk to the wolves (if the bear has the upper hand due to strength and size) or to the bear (if the wolves are too numerous or persistent). While wolves usually dominate grizzly bears during interactions at wolf dens, both grizzly and black bears have been reported killing wolves and their cubs at wolf dens even when the latter was in defense mode . </P>

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