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What Do Brown Bears Eat?

Brown bears have a varied diet that includes many types of food. In this article, we look at what makes up the diet of a brown bear.

Brown bears are omnivores and will eat whatever is edible and available. Brown bears eat mammals, small reptiles and amphibians, fish, plants, fruits, nuts, berries, and insects. They will also feed on human food and will rummage through trash.

This article looks at what types of food these enormous bears need to fuel their large bodies.

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What Do Brown Bears Eat?

Although classed as carnivores, brown bears are omnivores and will eat almost anything. Being at the top of the food chain in their habitat, brown bears will eat most animals, including mammals, reptiles, amphibians, insects, and fish. They also eat a lot of fruit, nuts, and berries. Bears that are close to humans will also eat food that we eat or from trashcans.

Being such large animals, brown bears require an enormous amount of food to fulfill their dietary requirements and supply them with energy. When actively feeding, grizzly bears can eat between eighty to ninety pounds of food per day.  

Brown bears eat more in the fall than in the spring when they awaken after hibernation. Like the black bear, brown bears need some time before they can eat again once hibernation has ended. The digestive system takes a few weeks to start working correctly.

The varied diet of the grizzly bear is helped by the teeth structure of the grizzly bear. Brown bears have some teeth that are similar to canine teeth. These teeth are sharp, which allows them to eat meat.  

They also have molars, which allow them to eat and chew plant material. Grizzly bears are the most omnivorous bears in North America. They eat more meat than black bears but less than polar bears. They also eat fewer plants than black bears but more than polar bears.

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Mammals

The diet of a brown bear does depend on its geographical location. Brown bears are classed as carnivores, and they eat both small and large animals. Large mammals such as caribou, deer, moose, and muskox can all be taken down by an adult brown bear. However, grizzly bears would instead take down an injured, old, young, or weak individual to conserve energy.  

Brown bears will also use their claws to dig squirrels and voles from their burrows, especially in the spring after hibernation. Around this time, and once the snow has melted, grizzly bears can feed on animals that have died during the winter. Carcasses of bison, deer, elk, and moose that have not survived the winter months are essential for bears to feed on in early spring.  

Brown bears feed on the young calves of caribou, deer, elk, and moose between May and June. Grizzly bears learn where the calves are born. These areas stay the same each year, allowing the bears to return to them to prey on the young. Elk makes up a large portion of a brown bear’s diet in these months.

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Fish

The amount of meat that a brown bear eats will depend on whether the grizzly bears have access to a constant fish supply.  

Brown bears feed on salmon that are spawning. Research indicates that bears with access to spawning fish consume as much as 75% of fish in their diet. Without a supply of spawning fish, the amount of meat consumed can amount to less than 10%.

Brown bears have been seen to eat up to 100 pounds of salmon daily. This can amount to up to 40 salmon a day.  

During summer, brown bears in Alaska and British Columbia will feed on salmon. Only bears in those areas will travel to feed on the spawning salmon.

During July, salmon move through the rivers and lakes of Brooks Falls in Katmai National Park in Alaska. Salmon make a feast for the bears as it is one of the first streams that the pre-spawned salmon enter, with Brooks Falls creating a natural barrier.

Although grizzly bears are mostly known for eating salmon, they will feed on other fish species, such as trout, when available.

The amount of fish, the bear, eats depends on the time of the season. At the start of the spawning season, the bears will eat all parts of the fish. Later on, in the season, they will eat the most full of fat parts, neglecting the rest.

I have written this article if you want to know about bear hibernation.

Plants

Although brown bears can eat many meat and fish, they also eat plants. The digestive system of a brown bear is unlike ungulates such as deer and moose. Whereas deer and moose have four-chambered stomachs that break down plant matter with particular bacteria and enzymes, brown bears have a single-chambered stomach.

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The intestines and digestive tract of the grizzly bear are short, which helps them process food quickly. Tender plants can be processed through the system In just over 7 hours. Knowing the limitations of their digestion system, brown bears prefer to eat young, leafy plants rather than mature plants.

Brown bears will eat bulbs, forbs, fungi, grass, and tubers as part of their diet. They will also eat the bulbs, corms, and roots that grow beneath the surface. Brown bears have long claws, which allow them to dig plants up with ease. Some plants, such as biscuit root and sweetvetch, are essential to provide nutrition to the bears.  

When they wake up from hibernation, plants make up a large part of the bear’s diet. In spring, when bears awake, the plants are beginning to grow. The snow melts quicker at lower elevations, and bears use this to their advantage. Bears stay at lower elevations to feed before moving up to feed on the new, softer grasses when the snow melts.

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Insects

Grizzly bears eat insects as a vital part of their diet. Brown bears eat earthworms, wasp nests, ants, and beetle larvae. They feed on many moths, especially during the summer months. Grizzly bears can eat up to 40,000 moths in a day, making the moth a critical food source.

With each moth containing half a calorie, a bear needs to eat a vast quantity to consume enough calories. Some researchers have advised that a bear can eat six months of calories in a single month from feeding on moths.

Hundreds of thousands of army cutworm moths, also known as miller moths, live in Yellowstone National Park, migrating from the lowlands to feed on the wildflowers that grow in the National Park. During the day, the army cutworm moths live under rocks on the mountain slopes in boulder fields.  

Thousands of army cutworm moths sleep under the rocks in a boulder field, burrowing into the rockslides to avoid sunlight. This allows the bears to feast on large amounts of these moths. Brown bears are strong animals and can turn over the rocks and boulders with their paws. This allows them to feed on many moths at once.

Whereas bears do not generally share their territories, they will tolerate each other when there is plenty of food.

With the reduction of garbage dumps in the 1980s, some researchers believe that the brown bears in the Yellowstone area started eating more moths to replace the lost food source.

You can find out which National Parks you can see bears here.

Fruit and Nuts

During the late summer, brown bears come down to lower elevations to eat fresh berries. Chokecherries, huckleberries, raspberries, and rose hips provide extra calories for the bears in warmer months.  

During the fall, bears eat these sugar-laden berries to gain weight before hibernating. When there is less food in the wild, bears are more likely to raid human farms looking for sugary berries.

Brown bears also feed on nuts, with the whitebark pine tree’s nuts being a good food source.

The cones have plenty of nuts, especially in grizzly bear areas like Yellowstone National Park and Grand Teton Nation Park. Although the whitebark tree’s pine nuts grow high, brown bears have an excellent technique. Brown bears will raid nuts already harvested by squirrels.

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