Grizzly bear
When Meriwether Lewis and William Clark first described the grizzly bear, they wrote its name as grisley. That spelling can be read two ways. It can mean grizzled, as in hair tipped with grey. It can also mean grisly, something that inspires fear. The modern spelling assumes the first meaning. Yet in 1815 the naturalist George Ord formally classified the animal as Ursus horribilis, a name chosen for its character rather than its coat.
Today the grizzly bear, Ursus arctos horribilis, is described as a population or subspecies of the brown bear living in North America. It is also called the North American brown bear, or simply the grizzly. This documentary follows several questions about it. How can one animal be counted as dozens of species and then as hardly any? How does a bear get through a long winter without eating? What does a bear that eats mostly plants do to a forest? And why has the range of such a formidable animal shrunk so far?
In the 19th century, naturalists sorted North America's big brown bears into 86 distinct species. By 1928 only seven of those species remained. By 1953 a single species was left. Genetic testing has since placed the grizzly inside the brown bear, Ursus arctos, as a subspecies. The biologist R.L. Rausch found that North America has just one species of grizzly. Everywhere in the world the animal is a brown bear, and in North America it is called a grizzly, but it is one species.
The ancestors of these bears came from Eurasia. They first crossed into North America somewhere between 177,000 and 111,000 years ago. Most grizzlies descend from that first wave, which still dominates the mitochondrial family tree south of subarctic North America. Genetic divergences suggest that brown bears moved south around 92,000-83,000 years ago, when an ice-free corridor opened. The first fossils turn up near Edmonton and are about 26,000 years old. Around 33,000 years ago the bears of Beringia died out locally. After the Last Glacial Maximum, two closely related lineages arrived from Eurasia and repopulated Alaska and northern Canada. The Alexander and Haida Gwaii archipelagoes hold their own native lineage, which first appears around 20,000 years ago. In 2018 researchers sequenced the grizzly genome and found it to be 2,328.64 megabase pairs long, with 30,387 genes.
The old confusion over species came partly from looks. Coastal bears are larger and darker than inland grizzlies, which led scientists to treat them as separate. Kodiak bears were also once considered distinct. At one point researchers thought there were five kinds of brown bear, three of them in North America. In 1963 Rausch cut the number of North American subspecies to one, Ursus arctos middendorffi.
The question is still open. Traditional lists name many subspecies beside the mainland grizzly. They include the Alaskan brown bear, the California grizzly, the Dall Island brown bear, the Kodiak bear, the Mexican grizzly, the ABC Islands bear and the Stickeen brown bear. One study of mitochondrial DNA found no distinct genetic groups among North American brown bears. It suggested that these labels are unwarranted. The one exception was the ABC Islands bear, which carries genes introduced from the polar bear. No formal revision followed, and taxonomic authorities have not accepted the idea.
A few studies add another twist. They suggest that certain Alaskan brown bears, including the Kodiak and Alaska Peninsula bears, belong to a Eurasian lineage closer to Siberian brown bears. Far across the Pacific, the Ussuri brown bear is sometimes called the black grizzly. It is no closer kin to North American brown bears than any other brown bear subspecies. Y-chromosome testing is still needed before anyone can draw a reliable new family tree.
On the Alaska Peninsula, coastal grizzly males average 389 kg and females average 207 kg. These are the largest populations. In northern interior Canada the figures drop to 139 kg for males and 95 kg for females, similar to American black bears in the same area. Among brown bear subspecies, only the Kamchatka bear and the Kodiak bear outweigh the grizzly. A typical grizzly measures 198-240 cm in length, stands about 102 cm at the shoulder and has a hindfoot of 28 cm.
Grizzly fur runs from blond to nearly black. Brown with darker legs is the usual coat, and many bears have white or blond tips on the flank and back.
Across the range they share with black bears, one feature gives an adult grizzly away. It is a pronounced muscular hump on the shoulders, which black bears lack. The grizzly's face looks dished in profile, with short rounded ears. A black bear has a straight profile and longer ears. A grizzly's rump sits lower than its shoulders, while a black bear's sits higher. The front claws of a grizzly measure about 2-4 inches, against 1-2 inches for a black bear.
On the ground, grizzlies tend to chase animals that run from them. Anecdotes put their top speed at 56 km/h, but the fastest reliably recorded speed, at Yellowstone, is 48 km/h. They can also climb trees. Their bite has been measured at over 8 MPa, a pressure large enough to crush a bowling ball.
Grizzlies in cold country spend five to seven months of each year hibernating. The California grizzly lived in a warm climate and did not hibernate at all. In some places where food stays plentiful all year, grizzlies skip the winter sleep altogether. Before denning, a bear passes through a feeding frenzy called hyperphagia and can add about 180 kg. It often waits for a substantial snowstorm before entering the den, which lowers the chance that predators will find it. Dens usually sit above 1800 meters on north-facing slopes.
Once inside, the bear does not eat, defecate or urinate. It partially recycles its own wastes. Some professionals debate whether this is true hibernation, mostly because of body temperature and because bears can occasionally move around. Inland bears spend nearly half their lives in dens, while coastal bears with richer food spend less time there. Males emerge in early to mid-March. Females come out in April or early May.
Winter is also when cubs are born. A litter of one to four, usually two, arrives in the mother's den while she hibernates. Each cub weighs only about 450 g. The cubs live on milk until summer and then begin eating solid food while still nursing. During two years with their mother, their weight climbs from 4.5 kg to 45 kg.
A female grizzly does not reach sexual maturity until she is at least five years old. After summer mating, the embryo does not implant until hibernation, and a miscarriage can follow if she lacks proper nutrition. Gestation is approximately 180-250 days. A mother raises her cubs for up to two years and does not mate during that time. Three or more years may pass before her next litter. Males roam territories as large as 4000 square kilometers, so finding a female's scent is hard in thin populations. Fragmented groups risk inbreeding depression. The result is one of the lowest reproductive rates of any land mammal in North America.
A sow guards her cubs fiercely and can fend off predators, including larger male bears. Grown cubs may see their mother again, but both avoid each other. The average male lives about 22 years, and the average female about 26, since females skip the seasonal breeding fights. The oldest known wild inland grizzly reached about 34 years in Alaska, and the oldest coastal bear reached 39. Most grizzlies die in their first year, while captive bears have lived as long as 47 years.
At Brooks Falls in Katmai National Park and Preserve, grizzlies are well documented catching leaping salmon in their mouths. Salmon cluster at the base of waterfalls, which makes them easy targets. Elsewhere bears chase fish through shallows and pin them with their claws. At Brooks Falls and McNeil Falls, big males fight regularly for the best fishing spots.
Salmon fat helps explain why coastal bears grow so large that Alaskan grizzlies weighing 1200 pounds are not unusual. Yellowstone bears eat whitebark pine nuts, tubers, grasses, rodents, army cutworm moths and scavenged carcasses. None of these match the fat in salmon. Coastal bears also dig into the sand for razor clams and scavenge dead or washed-up whales.
Grizzlies belong to the order Carnivora and have a carnivore's digestive system, yet they are normally omnivores. Some estimates put plants at 80-90% of the diet. Berries matter most when available, including blueberries, huckleberries, soapberries and buffalo berries. In Yellowstone, miller moths gathered on mountain slopes can supply half of a bear's yearly calories. After an avalanche or glacier slide, many bears may share a meadow to feast on the legume Hedysarum. When food grows scarce, they drift apart again.
Meat comes in many forms. In Denali National Park and Preserve, grizzlies chase, pounce on and dig up Arctic ground squirrels. Bears overturn rocks to reach hoary marmots, sometimes while the marmots are hibernating. Moose and elk calves are such a target in Alaska and Yellowstone that bears may kill as many as 51 percent of those born in a year. In northern Alaska, bears take sick or old caribou and calves, and studies suggest they may follow herds year-round. They have even been recorded preying on muskox. Because adult bison and moose are dangerous prey, bears stalk them under cover and pick off the weak.
Yellowstone cutthroat trout supply the one known case of Rocky Mountain grizzlies feeding on spawning salmonid fish. Both the bears and invasive lake trout threaten the trout, and a slight chance exists that the trout could be eliminated.
The bears' habits reshape the land around them. Grizzlies eat fleshy fruit and excrete the seeds in a condition that can still germinate, and some studies show better germination in the nutrient-rich droppings. When they dig for roots, bulbs and ground squirrels, they stir the soil. Areas with both bear digs and undisturbed ground have greater plant diversity than undisturbed ground alone, and dug soil holds significantly more nitrogen. Bears also carry salmon carcasses into the woods. White spruce foliage within 500 meters of a salmon stream contains nitrogen that came from the fish. Along Alaskan and British Columbian coasts, bears often eat only the skin, brain and roe, leaving the rest for gulls, ravens and foxes.
An experiment in Grand Teton National Park in Wyoming tested what happens without top predators. When wolves and grizzly bears were removed, populations of herbivores grew. Plant structure and density changed, and fewer migratory birds followed. That result is the evidence for calling the grizzly a keystone predator.
When gray wolves were reintroduced to Yellowstone, visitors began to watch an old rivalry replay itself. Grizzlies typically use their keen sense of smell to find a kill, often an elk brought down by wolves. One wolf may try to distract the bear while the others feed. The bear may chase the wolves in return. If wolves press the attack, it is usually with quick nips at the bear's hind legs. The bear then sits and defends itself in a full circle. Rarely does either side die or suffer serious injury, since one carcass is seldom worth the risk. At wolf dens, wolves usually dominate, but both grizzlies and black bears have been reported killing wolves and pups there even when the wolves defended themselves.
Cougars generally give grizzlies a wide berth. If a grizzly arrives at a cougar's kill, the cougar usually yields. A cougar that stands its ground uses agility and claws to harass the bear from outside its reach until one gives up. Some anecdotes from the late 19th and early 20th centuries describe cougars and grizzlies killing each other. Jaguars could also threaten bears, but both species have vanished from the parts of the Southwest where they once overlapped. Grizzlies are still absent from the border region where jaguars appear to be returning.
Smaller scavengers are treated as pests rather than rivals. Coyotes, foxes and wolverines try to steal scraps from a feeding bear. Wolverines are bold enough to persist until the bear finishes, which leaves them more food than usual. Packs of coyotes have displaced grizzlies from kills. The removal of wolves and grizzlies from California may have sharply reduced the abundance of the endangered San Joaquin kit fox.
Black bears eat a more herbivorous diet, so they compete less for food. When the two clash, the grizzly is usually the aggressor. One confirmed observation shows a grizzly digging out, killing and eating a black bear during hibernation. On many Pacific coastal islands off British Columbia and Alaska, bears of one kind live there but rarely both. Where they share ground, they split it by forest age, elevation and openness. Grizzlies favor old, productive forest and higher, more open country. A bear shot in Michigan in autumn 1986 was thought by some to be a hybrid because of its size and large skull. DNA testing could not settle whether it was a big black bear or a grizzly.
Global warming has brought grizzlies and polar bears into contact more often. The grizzly is usually the more aggressive, but healthy polar bears seem to dominate. Meetings do not always end in conflict. Some produce hybrids, called grolar bears or pizzly bears depending on the sex of the parents.
Among the Gwichʼin, a traditional grizzly hunt required the preparation and ceremony of intertribal warfare. It was never attempted without a party of four to ten warriors. Whoever dealt the killing blow earned great esteem. Many tribes living among brown bears viewed them with a mixture of awe and fear and rarely hunted them, especially alone. Native Californians avoided prime bear habitat and would not let young men hunt alone. During the Spanish colonial period, some tribes asked colonists for help with problem bears. Writers in the American West described Natives and voyageurs with lacerated faces and missing noses or eyes.
Myths carry the same respect. In Kwakiutl mythology, black and brown bears became enemies when Grizzly Bear Woman killed Black Bear Woman for being lazy. Black Bear Woman's children then killed Grizzly Bear Woman's cubs. Sleeping Bear Dunes is named for an Ojibwe legend in which a mother bear and her two cubs swam across Lake Michigan. The cubs drowned and became the Manitou islands, and the mother slept on the shore until sand buried her as a dune. In the Yukon, the Gwichʼin tell of atsanh or luu tun, the ice bears. Western anthropologists once thought them mythological. They are grizzlies that delay hibernation to follow late salmon runs, rolling in sand and then water until icicles cover their hides. The Gwichʼin describe the ice as insulation and as armor against hunters.
Grizzlies defend themselves and their young more aggressively than black bears do. Adults do not climb trees well, so they stand their ground. Sows with cubs are responsible for 70% of humans killed by grizzlies. Still, grizzlies normally avoid people and rarely hunt them. Most attacks follow a surprise at close range, especially when a bear guards food or cubs.
In British Columbia, the government kills approximately 50 problem bears each year and spends over one million dollars on complaints, relocations and eliminations. Problem bears are those that have adapted to human activity. Rubber bullets, foul-tasting chemicals and noise devices do little once a bear links people with food. Revelstoke shows the alternative. In the ten years before its education program, 16 grizzlies were euthanized there and 107 were relocated. The Revelstoke Bear Aware Society, a registered charity, launched its program in 1996. In the first six years, to 2002, only four grizzlies were eliminated and five relocated. These programs teach residents to secure garbage, pick fruit when ripe, fence livestock with electricity and keep pet food indoors.
Campers who hang food between trees follow a common but unreliable practice. A bear-resistant container works better. Hiking in a group of six or more significantly lowers the chance of injury but does not remove it. In November 2025, a grizzly attacked a group of 20 students near Bella Coola, British Columbia, and seriously injured four people, three of them children.
In the 21st century, ecotourism has boomed in Alaska, and most visitors come to watch bears rather than hunt them. Katmai National Park and Preserve lies about 300 miles southwest of Anchorage and holds an estimated 2,100 bears. At Brooks Camp, visitors watch from a platform as grizzlies catch salmon, and a webcam streams the scene online. About 100 bears gather there. At the McNeil River State Game Sanctuary and Refuge, an estimated 144 individual bears have been identified at the falls in one summer. As many as 74 appeared at once, and 100 in a day is not unusual. The refuge has been closed to grizzly hunting since 1995, and the Katmai-McNeil area holds an estimated 2,500 grizzlies.
Admiralty Island in southeast Alaska was known to early natives as Xootsnoowú, meaning fortress of bears. It is only 90 miles long yet holds an estimated 1,600 grizzlies, the densest population in North America. At Pack Creek, 20 to 30 bears can be seen at one time from a platform. An estimated 3,500 Kodiak bears live on Kodiak Island, 2,300 of them in the Kodiak National Wildlife Refuge.
The California grizzly appears on the state flag and symbolized the Bear Flag Republic before California joined the Union in 1850. The animal itself is extinct. The last known California grizzlies were killed in the Sierra foothills east of Fresno in the early 1920s. In 1936 the last grizzly in Arizona was killed on Escudilla Mountain, an event noted by Aldo Leopold in A Sand County Almanac of 1949. No grizzly has been confirmed in Colorado since 1979.
Grizzlies once ranged from Alaska to Mexico and as far east as the western shores of Hudson Bay. They also lived across much of the Great Plains and the southwestern states. Between Canada and the United States, they now hold about half of their historical range. They survive in Alaska, western Canada and parts of the northwestern United States, as far south as Yellowstone and Grand Teton National Parks. Around 60,000 live in North America, and 30,000 of those are in Alaska, where coastal food such as salmon is abundant. About 25,000 bears lived in British Columbia when European settlers arrived. A revised count in 2012 gave 15,075. In 2003, researchers from the University of Alberta spotted a grizzly on Melville Island in the high Arctic, the most northerly sighting ever documented.
In the lower 48 states, around 1,000 bears live in the Northern Continental Divide in northwestern Montana, and 70-100 in northern and eastern Idaho. In the North Cascades of Washington, fewer than 20 remain. A National Park Service and Fish and Wildlife Service process to restore bears there began with an environmental impact statement in fall 2014. A final plan followed in spring 2017. In September 2007, a hunter killed a male grizzly in the Selway-Bitterroot Wilderness, evidence that bears were still present there.
Legal protection has swung back and forth. The grizzly is listed as threatened in the contiguous United States and endangered in parts of Canada. In May 2002, Canada's Species at Risk Act listed the Prairie population of Alberta, Saskatchewan and Manitoba as extirpated. In Alberta, DNA hair-snagging studies in 2000 suggested a population of 841 bears. A recovery plan in March 2008 indicated the population was lower than believed, and in 2010 the province listed its roughly 700 grizzlies as Threatened.
On the 9th of January 2006, the US Fish and Wildlife Service proposed to remove Yellowstone grizzlies from the threatened list. It delisted them in March 2007. Several environmental groups, including the NRDC, sued. On the 22nd of September 2009, Judge Donald W. Molloy reinstated protection because whitebark pine, whose nuts feed the bears, was declining. The service proposed delisting again in March 2016, noting that the population had risen from 136 bears in 1975 to an estimated 700 in 2017. It delisted the bears in June 2017. Conservation and tribal organizations argued that the bears remained genetically vulnerable and sued in Crow Tribe et al v. Zinke. On the 30th of July 2019, the Yellowstone grizzly was returned to federal protection.
Conservation now depends on connecting what is left. The Khutzeymateen Grizzly Bear Sanctuary on British Columbia's north coast covers 44,300 hectares, with limited public access and a strict no-hunting policy. At Grouse Mountain in Vancouver, a five-acre refuge has housed two orphaned grizzlies since 2001. Roads and urban development split habitat and block gene flow, as in Banff National Park. Planners respond with park-forest corridors, tunnels and overpasses. GPS collars show that most corridors are used infrequently, and females are less likely than males to use them. That can limit mate access and reduce the number of offspring.
Recovery is expected to be slow because grizzlies reproduce slowly and because returning a large animal to farmland and ranchland brings conflict. Hunting rules remain contested as well. Theresa Pierno of the National Parks Conservation Association said more than 70,000 Americans opposed baiting bears with grease-soaked donuts in Denali National Park and Preserve. Alaska sued over the federal rules that restrict such methods. In a press release on the 3rd of October 2022, a federal district court in Alaska was reported to be returning to review a National Park Service hunting rule, including bear baiting. The rule stays in place during its revisions.
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Common questions
What is a grizzly bear?
The grizzly bear, Ursus arctos horribilis, is a population or subspecies of the brown bear living in North America. It is also called the North American brown bear or simply the grizzly.
How did the grizzly bear get its name?
Meriwether Lewis and William Clark first described the grizzly bear as grisley, which can mean grizzled or fear-inspiring. The modern spelling assumes the grizzled meaning, and naturalist George Ord formally classified it in 1815 as Ursus horribilis.
How many species of grizzly bear were there?
In the 19th century the grizzly bear was classified as 86 distinct species. By 1928 only seven remained, and by 1953 only one, because genetic testing shows it is a subspecies of the brown bear.
How can you tell a grizzly bear from a black bear?
A grizzly bear has a pronounced muscular hump on its shoulders, a dished-in face profile and short rounded ears. Its rump is lower than its shoulders, and its front claws measure about 2-4 inches.
How long do grizzly bears hibernate?
Grizzly bears hibernate for five to seven months each year, except where the climate is warm. During that time they do not eat, defecate or urinate, and females give birth in the den.
How many grizzly bears are left in North America?
Around 60,000 wild grizzly bears live in North America, and about 30,000 of them are in Alaska. In the lower 48 states, roughly 1,000 live in the Northern Continental Divide of Montana.
Where is the best place to see grizzly bears in Alaska?
The McNeil River State Game Sanctuary and Refuge has the greatest concentration of brown bears in the world, with an estimated 144 individuals identified at its falls in a single summer. Brooks Camp in Katmai National Park and Preserve offers platform viewing and a webcam.
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