Brown bears, often referred to as grizzly bears, are among the most iconic and awe-inspiring creatures of North America and beyond. These majestic mammals are known for their immense size, strength, and distinctive hump on their shoulders.
With the scientific name Ursus arctos, they are part of the Ursidae family and are considered apex predators in their home range. In this collection of 101 facts about brown bears, we’ll explore their physical characteristics, behavior, habitat, diet, reproduction, and much more.
From their impressive size and strength to their unique abilities as swimmers and climbers, these facts will provide you with a comprehensive understanding of these remarkable animals.
- Brown bears, also known as grizzly bears, are predominantly found in North America.
- Some species can also be found in Northern China, Korea, and Russia and are called Eurasian brown bears.
- Adult male grizzly bears can weigh more than 500 kilograms.
- An adult male grizzly is up to twice the weight of a female grizzly of the same age range.
- They have a concave or dish-shaped face with very high brows.
- Grizzly bears have short ears, short tails, and a rump lower than their shoulders, distinguishing them from black bears.
- Mature grizzly bears are apex predators in their home range.
- Their home range is situated where there are plenty of rivers, streams, and sometimes fruit-bearing trees.
- The actual weight of grizzly bears fluctuates and depends on the time of the season.
- Female bears are more miniature than male bears (they are just about 60% of an adult male grizzly bear size).
- Grizzlies have a lifespan of more than 30 years.
- Grizzly bears have different coat colors, such as dark brown, silvery, and light brown coats.
- Grizzly bears have long, sharp claws designed to help them forage and dig.
- Grizzly bears are omnivorous animals, with berries and nuts comprising approximately 80% of their nutrition.
- They eat insects, especially bees, ants, moths, and ladybugs.
- Some accounts suggest that grizzly bears cover their tracks from hunters.
- Male grizzly bears eat more meat than female grizzly bears.
- Grizzly bear meat consumption comes from small animals and rodents, although they can sometimes bring down large animals if needed.
- The IUCN Red List considers brown bears as Least Concern.
- There are approximately 55,000 grizzly bears in North America.
- There are about 15,000 grizzly bears in Canada alone.
- The Alaskan province has the highest population of grizzly bears, with a population of 30,000.
- Grizzly bears are adept at spotting rodent holes.
- Grizzly bears can climb well as cubs but rarely attempt to climb as adults due to their claws.
- Grizzly bears have sharp eyesight and can see better than humans in some lighting conditions.
- They recognize shapes but not too many details.
- Grizzly bears can walk on their hind legs in a manner similar to humans.
- Grizzly bears have fur on their bodies but have hairs on their shoulders. The hair on their backs has white tips, giving them a grizzled look.
- A mature grizzly bear’s height is about 3 to 4 feet when on all fours, but they can stand up to about 8 feet tall on their hind legs.
- The hump on their back can be used to recognize grizzly bears, and it is made of muscle, distinguishing them from black bears.
- Most grizzly bears hibernate for about 5 to 8 months every year, typically during the winter.
- Growling, roaring, and snorting are some of the ways grizzly bears communicate.
- In captivity and without regular exercise, a grizzly bear can weigh up to 1400 pounds.
- Grizzlies have dens where they stay during hibernation.
- Grizzly bears can gain more than 150 kg by feeding before hibernating.
- Grizzly bears do not eat, urinate, or defecate during the entirety of their hibernation period.
- They look around when people or animals are nearby, not because they can’t see, but to get a strong smell of the animal or person in the air.
- The length of a mature grizzly bear’s front claws is about 2 to 4 inches.
- There are very few predators that can hunt or harm grizzly cubs.
- Mature grizzly bears have no predators except human beings.
- Grizzly bears have their mating season from May to July.
- They are ready for mating at about five years of age.
- Male grizzly bears usually find it challenging to track female grizzlies due to the low population of females.
- Brown bears have a gestation period of 180 to 250 days.
- Grizzly bears are among the terrestrial mammals in North America with low reproductive rates.
- Brown bears can breed with other bears, such as polar bears and North American black bears.
- Cross-bred hybrid bears are rare.
- Female grizzly bears delay embryo implantation until they are about to hibernate.
- Miscarriages can occur in grizzly bears when they do not gain enough weight before hibernation.
- Brown bears give birth to an average of two cubs.
- A sow will attack anything she perceives as a threat to her cubs, even grizzly bears, and larger predators.
- Cubs are born while the sow is in hibernation in a winter den.
- It takes six weeks after birth for a cub to open its eyes.
- Female grizzlies live longer than their male counterparts because male bears often sustain injuries in fights.
- Grizzly bears only congregate when a significant amount of food is present in a particular location.
- Male brown bears are usually solitary animals, while sows move together with their cubs for a period.
- Grizzly bears are scavengers and can feed on carcasses if necessary.
- They also eat cooked human food and garbage but rarely kill humans for food.
- Grizzly cubs stay with their mothers for about 2 to 3 years or 2 to 3 summer seasons.
- Female grizzly bears do not mate when they are still caring for their cubs.
- Grizzly cubs feed only on their mother’s milk until the end of winter and then eat small solid foods while still drinking milk.
- Grizzly bears do not mark the territory that they defend.
- They rest frequently to conserve energy and eat to prepare for hibernation.
- Grizzly bears prefer salmon as their protein source but can also eat meat if they have no access to fish.
- Brown bears do not have multi-chambered stomachs even though they eat plant fibers like ruminants such as cows and elk.
- Grizzlies are skilled at catching fish and entering shallow waters to catch salmon.
- Grizzlies only tolerate other bears in their home range when there is plenty of food during salmon spawning season.
- When they are about to hibernate, brown bears can eat more than 25 fish per day to gain fat for the winter.
- During hibernation, a grizzly bear’s metabolic process and heart rate slow down to conserve fat reserves.
- A grizzly bear’s heartbeat slows to 8 beats per minute from its usual 40 bpm during hibernation.
- Grizzlies can recycle their body wastes during hibernation.
- Even during hibernation, grizzly bears can wake up and move around when needed.
- Some grizzly bears do not hibernate because they live in areas with food available year-round.
- Grizzly bears wait for snowfall to camouflage their dens from predators before hibernating.
Bryan Harding is a member of the American Society of Mammalogists and a member of the American Birding Association. Bryan is especially fond of mammals and has studied and worked with them around the world. Bryan serves as owner, writer, and publisher of North American Nature.