Grizzly bear

Classification and Evolution

The grizzly bear is classified as a subspecies of the brown bear (Ursus arctos). The name 'grizzly' is derived from 'grizzled', referring to the grey-tipped or silver-tipped hair that often characterizes its fur, though early explorers like Meriwether Lewis and William Clark also noted its 'grisly' or fearsome appearance. Brown bears originated in Eurasia and first migrated to North America between 177,000 and 111,000 years ago. Most modern grizzly bears in southern regions belong to this initial founding population. Genetic studies reveal a complex history with subsequent migrations, including lineages that repopulated Alaska and northern Canada from Eurasia after the last glacial period. Historically, many grizzly populations were classified as separate species, but modern genetic testing confirms they are all the same species, Ursus arctos. The taxonomic status of various North American populations, such as coastal 'brown bears' versus inland 'grizzlies', remains an open scientific question, with some studies suggesting they should all be considered populations of U. a. horribilis.

The genome of the grizzly bear was sequenced in 2018, revealing a length of 2,328.64 megabase pairs containing 30,387 genes. This genetic research helps clarify relationships between populations. For instance, bears on the ABC Islands (Admiralty, Baranof, and Chichagof) show genetic introgression from polar bears, making them a genetically anomalous group. Other Alaskan populations, including Kodiak bears, have been suggested by some studies to be more closely related to Siberian brown bears than to other North American groups. Until a comprehensive taxonomic revision is completed based on deeper genetic study, many previously named subspecies, like the extinct California grizzly, are provisionally considered separate from the mainland grizzly bear.

Physical Description

Grizzly bears are among the largest brown bear subspecies, typically surpassed in size only by Kodiak bears and Kamchatka brown bears. Their size varies dramatically based on geography and food availability. Coastal grizzlies, with access to protein-rich salmon, are the largest. Males in the Alaskan peninsula average 389 kilograms, while females average 207 kilograms. In contrast, bears in northern interior Canada are much smaller, with males averaging 139 kilograms and females 95 kilograms, a size similar to local American black bears. Average total length ranges from 198 to 240 centimetres, with a shoulder height around 102 centimetres. Newborn cubs are remarkably small, often weighing less than 500 grams.

Grizzly bear fur colour ranges from blond to nearly black but is most commonly brown with darker legs. The flank and back hair is often white or blond-tipped, creating a grizzled appearance. Several key physical characteristics differentiate grizzlies from the black bears with which they share some range. The most prominent is a pronounced muscular hump on the shoulders, which black bears lack. Grizzlies have a concave or 'dished' facial profile with short, rounded ears, whereas black bears have a straighter profile and longer ears. A grizzly's rump is lower than its shoulders, while a black bear's rump is higher. Finally, a grizzly's front claws are formidable tools for digging, measuring 51 to 102 millimetres long, compared to a black bear's 25 to 51 millimetre claws.

Range and Population in Canada

Historically, grizzly bears ranged from Alaska down to Mexico and as far east as the western shores of Hudson Bay. That range has since contracted significantly. In Canada today, grizzlies occupy British Columbia, Alberta, the Yukon, the Northwest Territories, Nunavut, and the northern part of Manitoba. As of 2002, approximately 25,000 grizzly bears lived in Canada, with the majority in British Columbia. An article from 1954 suggested they may have once been present on the Ungava Peninsula and northern Labrador. In British Columbia, grizzlies still inhabit about 90 percent of their original territory, though populations have declined from an estimated 25,000 at the time of European settlement to about 16,000 in 2008, with a revised count of 15,075 in 2012. Population estimates use methods like hair-snagging for DNA analysis, mark-and-recapture, and statistical modelling.

The most northerly documented sighting occurred in 2003, when researchers spotted a grizzly on Melville Island in the high Arctic. Overall in North America, around 60,000 wild grizzlies were estimated in 2002, with 30,000 in Alaska and up to 29,000 in Canada. The Alaskan population is densest along the coast where salmon are abundant. The Admiralty Island National Monument in Alaska protects an exceptionally dense population of about 1,600 bears on a 1,600 square-mile island. Grizzly bears have been extirpated from most of the Great Plains and southwestern parts of their historical range. Combining Canada and the United States, grizzlies now inhabit roughly half the area they once did.

Biology and Life Cycle

Grizzly bears hibernate for five to seven months each year, a period during which females give birth. To prepare, bears enter a state of hyperphagia, consuming vast amounts of food and gaining up to 180 kilograms to survive the winter without eating, drinking, urinating, or defecating. They typically dig dens on north-facing slopes above 1,800 metres in elevation, often waiting for a substantial snowstorm to conceal the entrance. There is some scientific debate about whether bears are true hibernators, as their body temperature does not drop as drastically as in smaller mammals, and they may occasionally move. Coastal grizzlies with year-round food access spend less time in dens, and in some plentiful areas, they may skip hibernation altogether. Males usually emerge from dens in early to mid-March, while females with new cubs emerge in April or early May, as seen in Yellowstone National Park where the first grizzly sighting of 2026 was a male on March 9.

Grizzly bears have one of the lowest reproductive rates of North American terrestrial mammals. Females do not reach sexual maturity until at least five years old. After summer mating, embryo implantation is delayed until hibernation, and miscarriage can occur if the mother's nutrient reserves are insufficient. The gestation period is approximately 180 to 250 days. Litters range from one to four cubs, with twins being typical. The cubs are born tiny in the winter den and feed solely on their mother's milk initially. The mother cares for the cubs for up to two years, during which she will not mate again. After cubs leave, she may not produce another litter for three or more years. This slow reproduction makes population recovery a lengthy process. The average lifespan is about 22 years for males and 26 years for females, who avoid the risky seasonal breeding fights of males. The oldest known wild grizzlies reached 34 years inland and 39 years on the coast, while captive bears have lived to 47.

Diet and Ecological Role

Although classified as carnivores, grizzly bears are omnivores with a highly varied diet that shifts with season and location. They prey on large mammals like moose, elk, caribou, and bison, though they more often take calves or injured individuals rather than healthy adults. They are adept fishers, feeding on salmon, trout, and bass, which provides the high-fat diet responsible for the large size of coastal populations. Grizzlies readily scavenge carrion and will eat birds, eggs, rodents, and even raid the nests of bald eagles. In Yellowstone National Park, their diet consists largely of whitebark pine nuts, tubers, grasses, army cutworm moths, and scavenged carcasses. During salmon spawning season, bears gather in large numbers at fishing sites like Brooks Falls in Alaska, where they expertly catch leaping fish in their mouths or pin them with their claws.

Coastal Canadian and Alaskan grizzlies are generally larger than their Rocky Mountain counterparts due to the richer, fat-rich diet of salmon and clams. They also forage for razor clams, digging in the sand to find them. This dietary abundance means it is not uncommon to find coastal grizzlies weighing 540 kilograms. The bear's foraging behaviour, such as turning over soil and dispersing seeds through scat, makes it a keystone species that shapes its ecosystem. Their predation and scavenging help regulate prey populations and recycle nutrients. The competition for prime fishing spots among large males is a dramatic display of their social hierarchy during times of plenty.

Conservation and Human Coexistence

The grizzly bear has legal protection in Mexico, European countries, some areas of Canada, and throughout the United States, but conservation status and management plans vary by jurisdiction. Repopulating its former range is expected to be slow due to the bear's low reproductive rate and human land use pressures like agriculture and livestock grazing. In Canada, populations in British Columbia are closely monitored, and efforts are ongoing to confirm sightings and manage human-bear conflicts. For example, the Simpcw First Nation has confirmed nine grizzly sightings between 2023 and 2025 in their territory, recording a total of 13 bears, indicating local monitoring efforts. In the United States, populations in the lower 48 states, such as the estimated 1,000 bears in the Greater Yellowstone Ecosystem, are the focus of recovery plans.

In areas like the North Cascades ecosystem in Washington, where fewer than 20 grizzlies are estimated to remain, long-term management plans include potential reintroduction to the national park. The story of the grizzly bear in North America is one of significant range contraction and local extinctions, such as the extinction of the California grizzly in the early 1920s. Modern conservation challenges include habitat fragmentation, which can lead to inbreeding depression, and the ongoing need for strategies that allow humans and bears to coexist safely. Public education on differentiating grizzlies from black bears, securing attractants like garbage, and understanding bear behaviour are critical components of these efforts across Canada and the United States.

Questions about Grizzly bear

How many grizzly bears are there in Canada?

As of 2002, there were approximately 25,000 grizzly bears in Canada, with the majority living in British Columbia. A 2012 revised count for British Columbia specifically estimated 15,075 grizzlies. Populations are also found in Alberta, the Yukon, the Northwest Territories, Nunavut, and northern Manitoba. These estimates are derived from methods like DNA-based hair-snagging inventories and mark-and-recapture studies. Population sizes have decreased from historical levels due to habitat loss and hunting.

What is the difference between a grizzly bear and a black bear?

Several key physical features distinguish grizzly bears from black bears. Grizzlies have a pronounced muscular hump on their shoulders, which black bears lack. A grizzly's face profile is concave or 'dished in' with short, rounded ears, while a black bear has a straighter profile and longer ears. A grizzly's rump is lower than its shoulders, whereas a black bear's rump is higher.

What do grizzly bears eat?

Grizzly bears are omnivores with a highly varied diet. They eat plants like berries, roots, and grasses, and animals including salmon, trout, rodents, and large mammals such as moose, elk, and caribou (often targeting calves or injured individuals). They are also prolific scavengers, feeding on carrion left by other animals. Coastal grizzlies have a richer diet of salmon and clams, which contributes to their larger size. In Yellowstone, their diet includes whitebark pine nuts, tubers, army cutworm moths, and scavenged carcasses.

How long do grizzly bears hibernate?

Grizzly bears typically hibernate for five to seven months each year, depending on the climate. They do not eat, drink, urinate, or defecate during this period. To prepare, they enter a phase of hyperphagia, consuming immense amounts of food and gaining up to 180 kilograms. Males usually emerge from their dens in early to mid-March, while females with new cubs emerge later, in April or early May. In regions with abundant year-round food, such as some coastal areas, grizzlies may hibernate for a shorter period or skip it altogether.

Where is the best place to see grizzly bears in Canada?

The best places to see grizzly bears in Canada are in western and northern regions where populations are healthiest. British Columbia holds the majority of Canada's grizzlies, with opportunities for sightings in many wilderness areas. Coastal regions, particularly during the salmon spawning season in late summer and fall, offer dramatic viewing as bears gather to fish. The Yukon also has significant populations, with sightings reported on northern road trips. Specific protected areas with high bear densities, like certain parts of Alaska's Admiralty Island, are renowned, but similar dense populations exist in remote coastal British Columbia.

Are grizzly bears endangered?

Grizzly bears are not globally endangered as a species, but many populations are of conservation concern. They have been extirpated from a significant portion of their historical range in North America, including the Great Plains and southwestern states. In Canada, they have legal protection, and populations are managed by provincial and territorial authorities. Their low reproductive rate makes them vulnerable to threats like habitat loss and human conflict. In the contiguous United States, populations in areas like Yellowstone and the North Cascades are protected and subject to recovery plans, highlighting their precarious status in those regions.

Sources: Wikipedia and current public reporting, checked by the Your Space Hamilton desk. Last updated 2026-10-19.