10 Incredible Facts About Grizzly Bears

Grizzly bears (Ursus arctos horribilis) are a subspecies of the brown bear. They are some of the largest predators on Earth, but did you know that 90% of their diet is vegetarian? Or that a grizzly bear’s sense of smell is hundreds of thousands of times greater than a human’s? We’re digging into 10 of the most incredible grizzly bear facts, so keep reading to learn more about these amazing animals.

1. The Grizzly Bear Diet Is About 80-90% Vegetarian

When most people think of grizzly bears, they assume they are strictly carnivores. With those teeth and that snarl, it’s no wonder. Surprisingly enough, grizzly bears aren’t carnivores, but omnivores, eating a mix of plants and animals. 

In the small corners of the world where grizzlies still freely roam the land, they exist primarily on a plant-based diet. Grizzly bears actually consume an average of 20% or less meat and flesh. From berries to grass and roots, grizzly bears will graze on all of the delicacies nature has to offer.

2. Grizzly Bears Can Be Cannibals

Cannibalistic bears may sound a bit dramatic, but the truth is that grizzlies sometimes eat their own young and smaller species of bears. Many male animals kill and eat their own young or the young of others. This is called infanticide, showing an instinctual and callous side of nature that many don’t want to see.

Sexually selected infanticide has been documented in grizzly bears as well as other species. In this mating system, males have nearly exclusive breeding rights with at least one female. Often, when the dominant male isn’t around, another male kills the offspring of the dominant male in an attempt to take the female as his own.

3. Grizzly Bears Are Tiny When They’re Babies

When grizzly brown bears are born, they weigh about one pound. This is surprisingly low, considering that adult males average from 400 to upwards of 700 pounds and adult females average from 250-350 pounds.

Grizzly bear cubs are very vulnerable, born without fur or the sense of sight. However, bear cubs bulk up quickly since the mother’s milk consists of about 33% fat. Bears usually reach their adult size in 4-6 years.

4. A Mere 2% of Grizzly Bears Remain in the Contiguous U.S.

The brown bear population is estimated at approximately 50,000 animals total in North America. However, only about 1,900 grizzly bears can be found in the contiguous U.S. Around 30,000-35,000 brown bears live in Alaska, but the exact number of grizzly bears in this population is unknown.

In total, 98% of the grizzly bear range in the contiguous U.S. has been eliminated in the last 100 years due to over-hunting and habitat loss. British Columbia, western Alberta, the Yukon, the Northwest Territories, and Alaska are the primary areas of distribution of North American grizzly bears. 

5. Wild Grizzly Bears Can Live to Be Up to 35 Years Old

Grizzly bears have one of the longest lifespans of any land mammal. The oldest wild grizzly bears are estimated to be at least 35 years old. Typically, however, bears live to be around 20-25 years old in the wild. Bears older than 40 years have been reported in captive populations.

Females tend to live longer than males because they do not participate in dominance fights. Males generally average about 22 years old, while females average closer to 26 years old.

6. Grizzlies Have One of the Lowest Reproductive Rates of Any Mammal

Unlike cats and dogs, which reach sexual maturity at a mere 5-8 months, bears spend a large part of their lives sexually immature. This contributes to one of the lowest reproductive rates of any mammal. Grizzly bears don’t reach sexual maturity until at least four years of age, but they may not begin breeding until they are over five. That is 1/5th of their life that they are not mating.

Grizzly bears only average around two cubs in each litter, and it may be 2-3 years in between litters. Fortunately, they have long lifespans, and females typically don’t stop reproducing until some time in their mid-to-late 20s.

7. What’s Good for Grizzly Bears Is Good for the Forest

Grizzly bears are an essential part of the wooded and mountainous ecosystems they inhabit. Grizzlies are eating more and more berries due to climate change and the timing of the seasons. However, they are dispersing the undigested seeds throughout the forest, complete with manure fertilizer to aid in the growth process.

Grizzlies even do their part in composting. Not in a leak-proof container like we do — they pull their weight. The grizzly bears dig and stir up the dirt, scavenging for carcasses winter has left behind, as well as for ground-dwelling rodents. Bears also forage for roots, bulbs, and grasses, increasing alpine ecosystems’ nitrogen levels and creating richer soil. 

8. Grizzly Bears Have a Better Sense of Smell Than Bloodhounds

Even the average dog can smell about 10,000-100,000 times better than a human. Bloodhounds hold the title for the best sniffer in the canine species. It may blow your mind to know that a bear’s sense of smell outperforms the bloodhound’s by seven times, which means a bear’s sense of smell is up to 700,000 times better than a human’s.

9. Grizzly Bears Have Super Long Claws

Yes, the grizzly bear is simply a type of brown bear, but there are specific characteristics that only the grizzly has. One of these attributes is massive, curved claws that can grow to be four inches long. That’s as long as a human finger, but with a sharp point at the end.

Other unique characteristics of the grizzly bear are the concave dips between their eyes and at the tip of their nose. Grizzly bears also have the signature grizzly hump between their shoulders. Grizzlies develop a larger-than-average shoulder hump from turning over rocks and frequently using their shoulder muscles.

10. Grizzly Bears Aren’t the Predators They’re Made Out to Be

We’ve all heard of grizzly bear attacks in the mountains. However, in truth, grizzly bear attacks are usually a response to feeling threatened. Just as with humans, grizzly bears don’t like to be surprised in their homes. In a study of over 7,000 grizzly bear encounters at Yellowstone from 1991-2022, grizzly bears attacked people in <1% of the interactions.

Campers and hikers in areas with grizzlies often carry bear sprays to deter aggressive run-ins with these massive creatures. Making some noise on the trail will alert bears that you’re approaching and give them ample time to take off. Grizzlies will show their fierce side if they believe their bear cubs, food or shelter are threatened, but they aren’t interested in stalking humans as some dramatizations may suggest.