Grizzly Bears: Apex Predators with a Plant-Based Preference

The grizzly bear (Ursus arctos horribilis), a subspecies of the brown bear (Ursus arctos) is a smaller, lighter-colored cousin. Grizzly bears are native to North America, from Alaska to Mexico. And though legend and literature portray grizzly bears, which can weigh as much as 900 pounds, as blood-thirsty carnivores, you might just be surprised by what a grizzly’s diet consists of. Continue reading to discover the truth about the grizzly bear’s dietary habits.

What Grizzly Bears Eat

Contrary to what we’ve been led to believe, grizzly bears aren’t savage carnivores, bent on ripping apart their prey in a feeding frenzy of flesh and bone. Grizzly bears are omnivores who feed on plants and animals, and the grizzly’s diet consists of 80-90% vegetation!  Yep, the majority of a grizzly bear’s diet is berries, grasses, nuts, and roots. These massive mammals will supplement their diet with salmon, small rodents, and ungulates such as deer, elk, and moose.

What grizzly bears eat is dependent on the time of year and what’s available. When grizzly bears come out of hibernation in the spring, there may not be a lot of options. During this time, grizzlies will scavenge for carrion, like dried fish carcasses and other dead animals that winter left behind. But as the snow melts away and the buds begin to blossom, grizzly bears forage for berries, nuts, and fresh spring grasses.

Competition  

As apex predators, grizzly bears do not have any natural predators, though grizzly cubs are vulnerable to predation from mountain lions, wolves, and other bears. Grizzlies’ principal competition for food resources is wolves. Habitat destruction is also taking its toll on grizzly bear populations. And while it’s still legal to hunt grizzly bears in Alaska, the Endangered Species Act (ESA) of 1973 makes it illegal to kill these majestic beasts in the lower 48 U.S. States.

How Does The Grizzly Bear’s Diet Affect Other Species?

The demise of the whitebark pine (Pinus albicaulis), a staple of the grizzly bear’s diet, has forced grizzlies to search elsewhere for food. Because of their shifting range, grizzlies are having closer encounters with humans and livestock in their search for adequate resources. This has created tension and bad feelings in the ranchers and farmers whose livelihoods are upended by the grizzlies, who are simply trying to survive in a hostile world.

How Much Do Grizzly Bears Eat?

Grizzly bears are grazing animals, eating more plants, berries, and insects than anything else. In the fall, when berries are abundant, grizzly bears can eat 200,000 a day. In the late summer months, moths are plentiful in the high altitudes of the Rocky Mountains, which suits grizzlies just fine. These big guys can eat up to 40,000 moths a day. Regardless of what they eat, grizzlies require about 90 pounds of food a day to survive. 

Are Grizzly Bears Dangerous to Humans?

Grizzly bears can be dangerous, like most animals trying to survive in the wild. Honesty, one could say that humans are more dangerous to grizzly bears than the other way around. A grizzly bear will not attack unless provoked. However, startling a grizzly is enough to provoke an attack. Grizzlies may also attack if they sense that their cubs are in danger or to defend their food.

What Do Different Types of Grizzly Bears Eat?

Grizzly bears eat what they can find, strongly depending on what is available. Bears near oceans feast on dead whales and seals that wash up on the shore, while bears near fresh streams, lakes, and rivers wait in the water to catch fatty fish like salmon. Coastal grizzlies will take full advantage of whatever sea life that particular body of water has to offer.

What Do Grizzly Bear Cubs Eat?

Grizzly cubs are born during winter hibernation and exist solely on the nutrition of their mother’s milk until the spring when they begin to try out solid foods. Thanks to the high-fat, nutrient-rich milk, grizzly bear cubs grow rather rapidly and can weigh 100 pounds by the time they leave their mother at two years old.

List: Foods Grizzly Bears Eat

• Carrion
• Marine mammals
• Plants
• Salmon 
• Fish
• Rodents
• Insects
• Moths
• Grass
• Tubers
• Sedges
• Pine seeds
• Acorns 
• Nuts
• Apples
• Berries
• Puffballs
• Roots
• Flowers
• Garbage

Newborn calves of:

• Moose
• Deer 
• Elk
• Caribou
• Sheep
• Mountain goats
• Bison
• Bears