**Classification and Evolution**
– Meriwether Lewis and William Clark first described the grizzly bear as grisley, with the modern spelling supposing the former meaning.
– Naturalist George Ord classified the grizzly bear as U. horribilis in 1815.
– The grizzly bear is a subspecies of the brown bear, with R.L. Rausch finding that North America has one species of grizzly.
– Brown bears originated in Eurasia and migrated to North America between 177,000 BP and 111,000 BP.
– Genetic studies suggest two closely related lineages repopulated Alaska and northern Canada after the Last Glacial Maximum.
**Appearance and Subspecies**
– Grizzly bears are among the largest brown bear subspecies, with the largest populations being coastal grizzlies in the Alaskan peninsula.
– Grizzlies have distinctive characteristics like longer claws adapted for digging, brown fur with darker legs, and a pronounced muscular hump on their shoulders.
– Different subspecies of grizzly bears have been provisionally considered separate, with coastal grizzlies being larger and darker.
– Genetic studies suggest the ABC Islands bear has genetic introgression from the polar bear.
**Range and Populations**
– Grizzly bears ranged from Alaska down to Mexico and as far east as the western shores of Hudson Bay.
– Currently, they are found in Alaska, much of western Canada, and portions of the northwestern United States.
– Approximately 25,000 grizzly bears in Canada occupy various territories, with Alaska having the highest population of 30,000 individuals.
– Lower 48 United States house around 1,000 grizzly bears in specific regions, with the North Cascades ecosystem in Washington having fewer than 20 grizzly bears.
**Biology and Behavior**
– Grizzly bears hibernate for five to seven months each year, with females giving birth during hibernation.
– They are solitary except around food sources during salmon spawn and have low reproductive rates due to ecological factors.
– Grizzlies are omnivores, with coastal bears having richer diets and inland bears feeding on whitebark pine nuts, tubers, and rodents.
– They prey on large mammals, fish, carrion, berries, grass, and insects, with grizzlies in Yellowstone known to eat Yellowstone cutthroat trout.
**Interaction with Humans and Cultural Significance**
– Native American tribes living near brown bears often hold a mixture of awe and fear towards them, with bears holding cultural importance in Native American folklore and traditions.
– Grizzlies are more aggressive than black bears when defending themselves, with most attacks resulting from close-range surprises or mothers protecting offspring.
– Increased human-bear interaction leads to problem bears, with aversive conditioning methods attempting to deter bears from humans.
– Cultural legends and stories surrounding grizzly bears include the Sleeping Bear Dunes legend and the Ojibwe legend of cubs becoming Manitou islands.
The grizzly bear (Ursus arctos horribilis), also known as the North American brown bear or simply grizzly, is a population or subspecies of the brown bear inhabiting North America.
| Grizzly bear Temporal range: Pleistocene – Present
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Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Carnivora |
| Family: | Ursidae |
| Genus: | Ursus |
| Species: | |
| Subspecies: | U. a. horribilis
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| Trinomial name | |
| Ursus arctos horribilis (Linnaeus, 1758)
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| Possibly synonymous subspecies | |
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| Historic and present range | |
In addition to the mainland grizzly (Ursus arctos horribilis), other morphological forms of brown bear in North America are sometimes identified as grizzly bears. These include three living populations—the Kodiak bear (U. a. middendorffi), the Kamchatka bear (U. a. beringianus), and the peninsular grizzly (U. a. gyas)—as well as the extinct California grizzly (U. a. californicus†), Mexican grizzly (formerly U. a. nelsoni†), and Ungava-Labrador grizzly (formerly U. a. ungavaesis†). On average, grizzly bears near the coast tend to be larger while inland grizzlies tend to be smaller.
The Ussuri brown bear (U. a. lasiotus), inhabiting Russia, Northern China, Japan, and Korea, is sometimes referred to as the "black grizzly", although it is no more closely related to North American brown bears than other subspecies of the brown bear around the world.