The grizzly bear (Ursus arctos horribilis) is also known as the North American brown bear. It is the third-largest bear belonging to the family Ursidae, which includes eight species of bears. They can be found in Montana, Wyoming, Idaho, Washington, and Western Canada, but more than 50% of grizzlies live in Alaska. They are solitary and territorial animals that spend most of their time searching for food.
Contrary to popular belief, grizzlies prefer to avoid people and only attack when provoked, usually in defense of their territory or cubs.
1. Grizzly Bears Are Omnivores
Grizzly bears are opportunistic eaters. This means they eat whatever they can find to fulfill their energy needs. Being omnivores means they will eat plants, berries, fish, and other mammals. Believe it or not, this ferocious bear’s diet is only about 10% meat!
Their diet changes depending on the type of year and what they can find. Grizzly bears in Canada and Alaska are bigger than the grizzlies in Yellowstone National Park as they have access to food sources with higher fat content. Grizzlies found in Yellowstone range from 200 to 700 pounds, whereas an Alaskan grizzly can weigh up to 1,200 pounds!
A grizzly’s diet will consist mainly of elk and bison in the spring. They will search holes for gophers and eat a variety of grasses, dandelions, clover, and ants. A grizzly won’t hesitate to scavenge on animal carcasses, and they will face off with a pack of wolves to steal their kill. However, U.S. wolves will rarely attempt to fight a grizzly and will retreat if they encounter one.
In the summer, a grizzly will continue to feed on vegetation. They will eat strawberry, huckleberry, and other berry varieties as the growing season continues. They will head to the rivers and streams for fish. From June through September, they will feast on salmon as the fish swim upstream to spawn. In late summer, they scavenge on bull bison carcasses that died while competing for female bison.
Whitebark pine nuts are a grizzly bear’s favorite in early fall. They also feed on worms, ants, and vegetation. Larger grizzlies will prey on adult elk. A grizzly won’t hesitate to venture onto a rancher’s land and kill farmyard animals, such as sheep and cattle. Grizzly bears in Alaska will hunt moose and caribou.
2. Their Embryos Go Through Delayed Implantation
Delayed implantation is a fascinating reproductive strategy used in many bears, including the grizzly. Grizzlies mate in late spring or early summer, but a female grizzly’s embryo won't implant until months later when she has gained enough body fat and is ready for winter. The mother will give birth in late winter in her den.
Grizzly bear cubs are usually born in pairs. They enter the world blind, toothless, and hairless! For the first month of life, the cubs will snuggle against their mother for warmth and milk and focus on gaining their strength. Once spring arrives, the cubs are ready to discover the world around them. They have opened their eyes, grown teeth, and a thick fur coat and are ready to leave the den.
The cubs will remain by their mother’s side for three years as she teaches them vital survival skills. Unfortunately, despite being great animal mothers, half of the bear cubs don’t survive their first year due to illness, starvation, and predators.
3. They Have a Distinct Hump
The grizzly bear is the only bear with a prominent hump between its shoulder blades. This hump is a mass of muscle that helps the grizzly to dig deep into the dirt in search of food. The less threatening black bear can be brown and resemble small grizzly bears. If you don’t see a hump, don’t assume it’s not a grizzly bear! A grizzly bear’s hump may not be easily distinguishable depending on how the bear is standing.
4. Grizzly Bears Don’t Hibernate
You may be surprised to learn that grizzly bears don’t hibernate. They enter a mild hibernation called torpor, defined as a physical state of inactivity. They spend several months before winter packing on the pounds to prepare for their torpor. They will eat up to 20,000 calories during the fall months and gain three pounds a day!
Once in their dens, their body temperature will drop from around 100 to 95 degrees Fahrenheit, and their heart rate will slow from 50 to 15 beats per minute! This helps them lower their energy needs, so they usually don’t need to leave their den to eat or drink. They may stand or walk around their den, and there have been rare sightings of grizzlies outside their dens in the middle of winter. If a grizzly does not put on enough weight during the fall, it may be forced to leave its den in search of food before spring arrives.
5. They Have Really Long Claws
You probably already know that a grizzly bear has long claws, but did you know their claws may be longer than your fingers? That’s right! A grizzly bear’s claws can reach four inches long! These long claws help the grizzly to dig through the dirt in search of food, swipe salmon from the river, tear apart tree stumps in search of insects, and dig their dens.
A grizzly can’t retract its claws, so its footprints are easily distinguishable from most other animals. Black bears have shorter claws, and their toe pads are further apart.
Even though its long, sharp claws are primarily for digging, they can significantly damage an opponent. A grizzly bear swipe can deliver more than 600 pounds of force and win a fight with a single blow. There’s a reason why these animals are apex predators!
6. A Grizzly Can Run 40mph
Think you can outrun a grizzly bear? Think again! They may look large, bulky, and slow, but grizzly bears can reach speeds up to 40 mph. That’s as fast as many popular horse breeds!
That muscular hump between their shoulder blades gives their front legs incredible power. Their long claws dig into the dirt to help propel them forward in a sprint, giving them quite the advantage. This impressive sprint speed allows the grizzly to hunt moose, elk, caribou, and deer.
7. They Are a Brown Bear Subspecies
All grizzly bears are brown bears, but not all brown bears are grizzlies. Confusing right? Ursus arctos is the umbrella species for all brown bears, including the grizzly and Kodiak bears. The type of brown bear changes depending on geographical location. Bears that live off the coast and survive mostly off marine life are considered brown bears. The brown bears that live inland and consume more berries and vegetation are classified as grizzly bears. These amazing animals are native to Alaska.
Surprisingly, brown bears are bigger than grizzly bears. This is because a brown bear’s diet consists of more protein, allowing it to grow larger and develop more muscle. The Kodiak bear is the largest brown bear of all. A Kodiak bear can be over 10 feet tall on its hind limbs and weigh 1,500 pounds! A grizzly bear weighs closer to 700 pounds and stands around eight feet on its hind legs.
8. They Mate with Polar Bears
Due to climate change, Alaskan polar bears are moving further south in search of food, and grizzly bears are venturing further north. Every year, more grizzlies and polar bears come into contact. Sometimes these bears are seen stealing each other’s food, but they are mating too! This hybrid is called the “pizzly” or “grolar” bear.
The pizzly bear has cream-white fur, much like a polar bear but with brown patches that match a grizzly. It has long claws, a humped back, and a shallow face that resemble the grizzly bear.
The first wild sighting of a pizzly bear was in 2006 in the Northwest area of the Canadian Arctic, but they were being bred in captivity before that. There has been a steady increase in pizzly bear sightings since. This hybrid is fertile and can produce its own young, so it’s possible this new breed of bear could be here to stay.
9. They Are Smarter Than You Think
A grizzly bear’s intelligence is sometimes overshadowed by its enormous size and cute, cuddly features. Between those adorable ears is the largest brain-to-body size ratio of any land mammal! Wildlife biologists consider bears to be one of the most intelligent animals and compare their intelligence to higher primates, such as the proboscis monkey.
These animals have an incredible memory. A grizzly can remember where to find a food source they may have located ten years earlier! They have impressive navigational skills that are superior to humans. They study their surroundings to form detailed maps of their territories. Scientists believe bears may be able to understand a sense of natural beauty. They have observed bears sitting and staring at scenic rivers or mountain views for long periods.
