5 amazing facts about grizzly bears

November 17, 2016, 11:03 a.m.

1. Grizzlies are surprisingly fast. Though they look big, heavy and lumbering, they can really hussle, hitting speeds up to 30 miles an hour, or possibly faster. According to William E. Kearns, assistant park naturalist at Yellowstone, "[S]peeds have actually been recorded for the grizzly up to and including thirty miles per hour with the bear setting his own pace. What they might be able to do under 'pressure' or in anger is entirely a matter for supposition."

That's why experts advise to never try to run away from a grizzly. Not even Usain Bolt, considered the fastest human on Earth, could outrun one of these big bears. Even horses could have a tough time outrunning a grizzly. Kearns notes that grizzlies, "have considerable endurance, for covering two miles at from 25 to 28 miles per hour proves a stamina that would certainly try the best of horses."

2. There are fewer grizzlies in the United States than you might think. Defenders of Wildlife notes, "As many as 50,000 of these great bears once roamed across the Lower 48. But aggressive lethal persecution in the 1800’s and through the mid 1900’s reduced their numbers to only a few hundred." Decades of conservation efforts have helped bring the numbers back up a bit, and today there are around 1,800 grizzlies in 5 populations in the Lower 48, mostly in Glacier and Yellowstone National Parks. While the population is strong enough that grizzlies may be removed from the Endangered Species List, continued conservation across all grizzly habitat is needed to keep their numbers from falling further.

3. Grizzly bears go by many names. Grizzlies in North America are subspecies of brown bear, so are often simply called brown bears when speaking about the species in general. But it gets more specific. Scientifically known as Ursus arctos, the subspecies under that umbrella include the mainland grizzly, Ursus arctos horribilis, the Kodiak grizzly, Ursus arctos middendorffi, and the peninsular grizzly Ursus arctos gyas. Aside from scientific names, there are also other nicknames. The light-colored guard hairs give the bear the common name of not only grizzly, but also silvertip.

4.Grizzly bears eat moths. They eat pretty much anything really — from roots and grasses, to berries and nuts, to fish to rodents, elk and even carrion. But these enormous bears also feast on army cutworm moths and the insects are considered an important food source for Yellowstone bears. The North American Bear Center writes, "During the summer months in the Yellowstone area, these moths congregate on sub-alpine plants located above the timberline at elevations higher than 10,000 feet. During the early morning hours these moths drink nectar and then during the day they cluster on the surrounding rocks. Grizzlies from all around climb to these high elevations to consume 10,000 to 20,000 of these moths a day."

5. Grizzly bears are fairly new to North America. Though the continent has had big bear species in the past, including the giant short-faced bear, grizzlies moved in only about 50,000 to 100,000 years ago, traveling in from Europe and Asia via the Bering Land Bridge. The move was so recent that grizzlies are still very closely related to the brown bears of Siberia and northeast Europe, and are still considered the same species, not a unique species.

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Editor's note: This file has been updated since it was originally published in July 2015.