When not hibernating, grizzly bears spend much of their time moving around looking for food. As a result, many U.S. national forests and parks inadvertently provide conflict meeting grounds between humans and grizzlies. Such confrontations can be disastrous for visitors, given the size of these animals and their penchant for feeding. For those who camp or hunt a lot outdoors, it's best to understand how grizzlies hunt for food to avoid being their next dinner.
Grizzlies have no problem wading into rivers and lakes for food, being skillful at catching fish with their claws and mouth. These bears usually place themselves smack in the middle of the watery traffic waiting for dinner to come to them. Salmon spawns in the Northwest Pacific draw grizzlies together at rivers and river mouths, creating colonies among animals that normally roam in solitary patterns.
Grizzlies roam extensively across the western half of Canada and down to the very northern reaches of the United States. These areas provide an abundant area of food sources because much of the land is rural and wild with significant animal populations.
Being extremely strong, these bears can take down mammals as big as bison and moose, but grizzlies eat just about anything. Their diet includes both meat and plants. In fact, plants make up 90 percent of a grizzly's diet in a given day.
Since food sources change through the seasons, grizzlies move around to keep their options open for feeding. Bears move based on past experience and hunting knowledge of food sources, so they seasonally migrate to stay fed.
Food Supply Affects the Hibernation Cycle
Grizzlies may avoid hibernation if the nearby food supply is plentiful. They have been known to feed right through winter, reverting to hibernation only when food gets scarce, in which case the bears can hibernate for up to eight months at a time. The deciding factor for hibernation length depends on how long cold weather continues.
Human Error Can Be Avoided
Particularly in campgrounds and trafficked camping areas, safe food storage is critical. Grizzlies have a keen sense of smell and sniff out food packed in containers or even inside cars. The last thing a park ranger wants is for a grizzly to become used to finding food among humans, because this ultimately means the bear will be put down, becoming too much of a risk to park visitors. As a result, all parks and campgrounds have rules regarding safe food security to avoid bear problems.
Grizzly bears are not above scavenging either. They will find food sources in leftover carcasses, dead animals and waste where other animals won't. In fact, when food is scarce during the winter, these bears have been known to recycle their own fecal waste as a food source. In Yellowstone National Park, grizzlies have an ongoing contest with wolves over food, frequently using the wolves to get carcasses without having to hunt for them. This approach doesn't always work though, if there are enough wolves to nip at the bear until it leaves.