Grizzly Bears

The grizzly (Ursus arctos horribilis), is found in the western U.S. states, mainly Alaska, Wyoming, Montana, Idaho, and Eastern Washington. Coastal versions of this species are known as “Kodiak” bears. The smaller inland variety is called the “grizzly” bear.  The California grizzly (Ursus arctos californicus) is an extinct subspecies.  All that remains of it is the bear on California’s flag. The grizzly’s thick fur varies from almost blond to light brown or almost black. Sometimes the bear’s fur looks white tipped on its back and shoulders, hence the “grizzled” appearance.  These bears are all members of the same species, though some biologists say that the brown bears living on Kodiak Island have been isolated long enough to be deemed a subspecies (Ursus arctos middendorffi). They are also found in Columbia, Alberta, the Yukon, and Canadian Northwest territories.

Despite apparent differences in size and color, black bears and grizzlies can be difficult to tell apart. Hunters kill several grizzlies a year by mistake, assuming they are black bears. It is therefore essential to distinguish the species correctly.  The best indicators are the size of the bear’s shoulders, the profile of the face and the length of the claws. The grizzly has a pronounced shoulder hump (pure muscle), a concave (“dished”) facial profile, smaller ears and much larger claws than the black bear.  Black bears have a flat “Roman-nose” like profile, larger ears, but smaller claws, and minimal or no visible shoulder hump.

Height:  3.3 feet (at shoulder)
Length:  6.5 feet
Mass:  Male: 600 lbs. (Inland area population). Female: 290 – 440 lbs.
Life Span:  20-25 years 

A grizzly stands about 7 feet tall on its hind legs and weighs from 300 to 600 pounds, sometimes more than 800 pounds, though grizzlies as massive as 1400 pounds have been encountered. Females are smaller, weighing between 200 and 440 pounds.  People often perceive a grizzly standing on its hind legs as showing aggression; bears actually stand when they are surveying their surroundings, or when curious. Otherwise, they usually remain on all fours.

The grizzly is omnivorous, it will eat whatever is abundant where it lives. On average, 75% of its diet is comprised of berries, leaves, and nuts. Grizzlies also like to eat fish, ungulate species such as elk and occasionally rodents. They also tear into rotten logs or turn over heavy stones for insects and larvae. During the salmon migration bears often enter shallow water in groups and catch salmon as they jump out of the water. They can eat up to 25 fish daily while preparing for hibernation, thus increasing their fat reserves. Bears enter a phase known as “hyperphagia” (increased eating) in the fall in preparation for hibernation. They can eat between 8,000-14,000 calories per day for black bears and up to 20,000 calories per day for grizzlies.

Male grizzlies lead solitary lives. Except for mating and caring for cubs, grizzly bears primarily are solitary, spending most of their time foraging for food. They are excellent swimmers and can run fast, up to 30 miles per hour. They have perfect eyesight and an excellent sense of smell, said to be better than that of hound dogs. Grizzlies live up to 30 years in the wild, up to 40 years in captivity.

Range and Population:
Historically, the grizzly bear’s range covered much of North America.  It extended from the mid-plains, west to California and from central Mexico north throughout Canada and Alaska. Today, the grizzly is found in about 2 percent of its original range in the lower 48 states. On average, grizzly bears need an extensive home range:  50 to 300 square miles for females; 200 to 500 square miles for males. Their territory includes diverse forests and moist meadows and grasslands near mountains. In the spring, bears usually roam at lower elevations, but move to higher altitudes for hibernation in winter.  From the 1800s to 1975, grizzly bears in the lower 48 states decreased sharply from an estimated population of more than 50,000 to less than 1,000.  Grizzlies were eliminated from much of the West by the late 1800s. Livestock depredation control, bear habitat deterioration, commercial trapping and unregulated hunting damaged the population considerably.  The unfortunate perception that grizzlies threatened humans was a leading cause of their decline. (See also “Predator Conservation” on our website for more detail)

Gestation:  180-250 days
Litter size:  1-4, average 2-3 cubs
Grizzly bears reproduce slowly. Females begin breeding at age four and typically become pregnant once every three years. Grizzlies breed from May through July. They may mate with multiple partners during a season. Because implantation of a fertilized egg is delayed, the embryo does not begin to develop until late November. This allows the sow to conserve energy before denning. In late January, early February she gives birth to one or two cubs, rarely three or four. The cubs are hairless and blind, about eight inches long, and weigh from 8 to 12 ounces. They don’t hibernate, but sleep next to the mother nursing, and growing fast. At about ten weeks, grizzly cubs weigh approximately 10–20 pounds.

Grizzly sows are protective and become extremely dangerous when approached while with cubs. The cubs can climb trees while young, however eventually lose this ability because of their long claws. Grizzly claws are long, like human fingers. Male grizzly bears do not participate in raising cubs and can pose a threat to the young bears. Grizzly cubs usually spend 2 to 4 years with their mother, before she or a suitor chases them away. Females often establish their home range close to their mother, but male cubs disperse farther away.

Threats to Grizzly Bears:
Human conflict and habitat destruction are the most significant threats facing grizzly bear populations.   Bears require large areas of secure habitat, but in an increasingly developed world, they often travel through private land in search of food.  Garbage, bee yards, chicken coops, fruit trees, and birdfeeders often lure bears near homes where they can become used to human activity.  Bears that become habituated to humans may be deemed a threat and killed by wildlife officials or landowners.  More often, this type of situation can be avoided.  Roads, subdivisions, energy development, and livestock operations also have a negative impact on the bears’ survival.  They need secure habitat to roam, and protecting corridors that connect grizzly populations is vital to their future.

Bear-Caused Injuries and Human Fatalities:  From 1980-2015, over 104 million people visited Yellowstone National Park. During that time, 38 people were injured by grizzly bears. For all national park visitors combined, the chances of being injured by a grizzly bear are very low; approximately 1 in 2.7 million. The risk is significantly lower for visitors that do not leave roadsides or park developments, but much higher for those hiking in the backcountry. When backcountry hiking, you can substantially reduce the odds of being injured by a bear by:  1) hiking in groups of three or more people,  2) making noise (especially in areas with poor visibility), 3) staying alert, 4) not running during encounters with bears, and 5) carrying bear spray.  During the 145-year history of Yellowstone National Park, eight people have been killed by grizzlies within the park. More people in Yellowstone have died from burns from falling into thermal pools, drowning, and suicide-related deaths than have been killed by grizzly bears.

Do not go into the backcountry, stay within the park and inquire about bear activity before hiking. Carry bear spray and attaching bells to your shoes can avoid unexpected encounters. Don’t hike alone in bear country.

When you see a distant bear:  If the bear doesn’t see you, keep out of sight, stay as far as possible behind and downwind of the bear. If the bear sees you, retreat slowly, then leave the area.  Regardless of distance, never approach a bear. When a bear is standing up on its hind legs, it is most likely trying to gather information, not being aggressive. In this situation, do not panic. Quietly back away, slowly.

Surprise Encounters: If the bear sticks out its lips, clacks its teeth, slaps the ground with its paws, or woofs, it is warning you that you are too close and making it nervous. Pay attention to this warning, and back away slowly. Do not run, make sudden movements or shout. Do not startle the bear. Running may trigger a chase response. And remember, you can’t outrun a bear. Often times, just by putting some distance between yourself and the bear and moving away slowly, will defuse the situation. Take your bear spray out of the holster, remove the safety tab, and be prepared to use it if the bear charges. Climbing a tree is a poor decision. Bears can climb trees.

During a surprise encounter with a bear, where it is reacting defensively, don’t fight back. This will only prolong the attack and will likely result in more severe injuries. Since 1970, people who played dead when being attacked by a bear, received only minor injuries 75% of the time. On the other hand, those that fought back during surprise encounters with a bear were severely injured 80% of the time.

If a bear has not reacted aggressively, has not initiated a charge or otherwise acted defensively, you should slowly back away. Never drop to the ground or “play dead” with a bear that has not been aggressive or defensive.

Charging BearsIf a bear charges after a surprise encounter, it is important to stay still, and stand your ground.  Usually, the bear will most likely break off the charge and/or veer away. Do not run, as this can trigger a chase response. If a bear charges and you have bear spray, use it.  Make sure you start spraying the charging bear when it is about 60 feet or closer.  If the bear continues to charge towards you, it is important not to drop down and “play dead” too early.  You must wait until the bear makes contact with you or immediately before the charging bear makes contact. By standing your ground, it is likely to break off the charge or veer away.

If the bear makes contact, then become passive, drop to the ground and “play dead.” Leave your backpack on to help protect your back, lie on your stomach while keeping your face down.  Clasp both of your hands over the back of your neck, allowing your elbows to protect the sides of your face. Remain still and silent to help convince the bear that you are not a threat.  After the bear leaves, it is important wait several minutes before moving. Listen, look around cautiously before you get up to make sure the bear is no longer nearby. Once the bear is gone, get up and walk (don’t run) out of the area. Remember, a sow needs time to gather up her cubs which may have climbed trees or hidden in nearby bushes. If you get up too soon before they have left, she may attack again.

Kodiak Bear (Ursus arctos middendorffi) or Alaskan Brown Bear
The Kodiak bear inhabits the Kodiak Archipelago in southwest Alaska. The Kodiak bear is the largest recognized subspecies of brown bear, one of the two largest bears alive, the other being the polar bear. The Kodiak is very similar to brown bear subspecies, like the grizzly (Ursus arctos horribilis) and the extinct California grizzly (Ursus arctos californicus), the main difference being size. The Kodiak, commonly reaches 660 to 1,300 pounds, at times exceeding 1,500 pounds. Females weigh up to 1000 pounds. Diet and lifestyle of the Kodiak are like that of the other brown bears.

The primary difference between the grizzly and Kodiak bear is where they live. The Kodiak range is limited to the islands of the Kodiak archipelago of southwestern Alaska. This population has been isolated from the mainland animals for about 12,000 years. The isolation of these bears has developed them into a subspecies. Grizzly bears are widespread and are found in inland areas of the Canadian Northwest Territories, British Columbia and Alberta, the Yukon, and the U.S. states of Alaska, Montana, Washington, Wyoming, and Idaho. The geographic differences between these two subspecies have also led to some differences in size. Generally, Kodiak bears have larger frames and bone structures than grizzlies, though both species can reach enormous proportions. Kodiak bears are just slightly smaller than polar bears and are considered among the largest of all bears.  Males can weigh up to 1,500 pounds and are able to stand up to 10 feet tall when on their hind legs. Grizzly bears can weigh up to 1,150 pounds.

The Kodiak’s habitat is able to support a higher population of bears due to abundant food sources. Therefore, Kodiak bears developed complex social structures and communication, which allows for living together with minimal conflict. More recently conservation efforts have become more aggressive, because of concern over the stability of the Kodiak population with regard to hunting.  However, there seems to be no threat with potential extinction. The Alaska Department of Fish and Game closely monitors the number of bears hunted in the state.  Currently, the total Kodiak population is about 3200 individuals.

The Kodiak bears thrive in a habitat with coastal areas, thick forests, rivers, abundant vegetation, plenty of salmon, and other animals for prey. They too feed on berries, nuts, insects, larvae, grass, leaves and certain roots. They like fish, especially salmon, which is abundant where they live and has a high oil content. Kodiak bears, as others, also have a keen sense of smell and good hearing. They too will stand on their hind legs to investigate smells and sounds, not to attack. Kodiak bears also pretend to attack via mock charges towards perceived attackers, but then stop short of actually attacking.


Breeding season is around May through July, and litter size averages 1 to 3 cubs.  Like other bears cubs, they are born blind and helpless. They weigh under 16 ounces. Occasionally cubs are subject to attacks by adult male bears.

The most significant threats to the Kodiak bear include the changes to the environment caused by climate change and attacks on their habitat by increased human development. Energy development projects can disrupt their behavior and ecosystem.


Wikipedia – Bears – Injuries


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