Ursus arctos - Brown bear

Ursus arctos - Brown bear

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Ursus arctos

Common name

: brown bear or grizzly


  • Body length: from 1 to 2.8 m
  • Height at the withers(1): 90 to 150 cm (which reaches 2.5 m when standing up on hind legs)
  • Weight: 100 - 600 kg (males larger than females)
  • Lifespan: 20-30 years in the wild; 50 years in captivity
  • Sexual maturity: female 2-3 years; male 3-4 years


The species Ursus arctos known in Italy as brown bear and in America comegrizzly belongs to the family Ursidae and it is a large animal quite widespread in different parts of the world. We find it in North America, Europe and Asia while it is now extinct in North Africa.

Certainly its population has contracted over the years but it is still large enough to currently occupy about 5,000,000 km² in the north-western regions of America, 800,000 km² in Europe (excluding Russia) and a large part of northern Asia. We find the largest number concentrated in Russia, Alaska (United States) and Canada.

In Italy we find the Marsican brown bear (Ursus arctos marsicanus), in the national park of Abruzzo, Molise and Umbria with a population reduced to no more than 30-50 specimens (very rough estimate as there are no precise data). A very small community ofUrsus arctos it is also found in the Alps; in fact, thanks to a repopulation policy, a certain number of brown bears from Slovenia were introduced for the reconstitution of a nucleus in the central Alps.

This mammal occupies a vast type of habitat from the steppes of Asia to temperate rainforests, often overlapping its range with that of the Tibetan bear (Ursus thibetanus) or with that of the polar bear (Ursus maritimus). It is an animal that can be found from sea level up to 5000 m of altitude occupying numerous habitats, even very different ones, in consideration of the fact that its diet is very varied. And its density varies according to the quantity of food: in areas where there is abundance there are also 10 brown bears per 100 km² with high reproduction rates.

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They are solitary animals and the only moments of socialization with their peers are the periods that a mother spends with the young or the short period in which male and female come together to mate.Another moment of coexistence is when different bears come together in a single place where there is abundant food (for example the time of hunting for salmon that go up the rivers to lay their eggs). When these alliances are formed, a hierarchy is always established where there will usually be a dominant male who will impose his authority by force.

Among these mammals, the most aggressive sex is certainly the female one when puppies are present.

They are animals that move mainly in the morning and in the evening even if this is not to be considered a fixed rule. They spend the rest of the day resting in small depressions in the ground they have dug.

Brown bears are considered extremely intelligent and very curious animals and have an excellent sense of direction which allows them to travel many kilometers without ever getting lost. They are able to travel enormous distances in search of food, for example during the period when the salmon go up the rivers or when the fruit begins to ripen.

They are animals that hibernate during the bad season which generally coincides with the months of October until February (but a lot depends on the area). In the southern areas, therefore with milder temperatures, the hibernation period is considerably reduced. Hibernation is a period of uninterrupted deep sleep during which the bear lowers its body temperature by several degrees. To pass this period, burrows are dug in the ground making a bed with dry leaves. These burrows can be used for several consecutive years.


The brown bear is one of the largest land carnivores, weighing even more than 700 kg (specimens weighing 780 kg have been found in Alaska).

They are animals characterized by a body covered with a dense dark fur, of a color that varies from brown, to cream, to black. In the rocky mountains there are numerous individuals characterized by a very long and thick whitish hair on the back which gives it a grizzled appearance (hence the name ofgrizzly "grizzled").

They are animals that have a lot of strength and are very agile: they can compete with a horse in the race or kill a cow with a single leg or easily drag a dead moose up a steep climb.

Buni bears have an excellent sense of smell and can hear prey even from three kilometers away. Vision and hearing are not particularly developed. They are skilled swimmers and climbers (even in trees).


It is a mammal that communicates mainly through vocalizations and smells.

Often when hunting, the bear makes various sounds or scratches or rubs itself on the bark of a tree to mark its territory.

Certainly its population has contracted over the years but it is still large enough to currently occupy about 5,000,000 km² in the north-western regions of America, 800,000 km² in Europe (excluding Russia) and a large part of northern Asia. We find the largest number concentrated in Russia, Alaska (United States) and Canada.


The diet is very varied and they can be considered omnivorous animals.

The type of food varies according to the season and therefore to availability and also to its geographical location. It is an animal that feeds on numerous plants such as fruit, roots, tubers, bulbs especially in the summer period; insects, larvae, small vertebrates such as squirrels, rabbits, marmots at all times of the year.

Brown bears that live in the Rocky Mountains are more carnivorous, feeding mostly on moose and other mountain mammals. They also feed on fish and do not disdain carrion.


Between the months of May and July, when the female brown bear goes into heat, a couple is temporarily formed for the purpose of mating. The estrus lasts on average from 10 to 30 days until the female mates.

A peculiarity is that the fertilized egg implants itself in the uterus only about 5 months after mating, usually in the month of November which corresponds to the period in which it hibernates. Then follows a gestation that lasts about two months after which the puppies are born (which therefore takes place between January and March, when the female is in hibernation). In practice, the total gestation period, from fertilization to the birth of the young, is 180-260 days.

A female typically gives birth to 2-3 cubs (can reach up to 5) which are very small at birth, hairless and blind and weighing about 350-650 grams. They grow very quickly, thanks to their mother's milk (they are mammals), so much so that at the age of three months they already weigh 15 kg while at six months 25 kg. They start eating solid foods at the age of five months although they will continue to be breastfed until the age of 18-30 months.

The little brown bears will stay with their mother until they reach 3-4 years of age. After which they are chased by their mother away from her territory. Once the young are gone the female goes into estrus and begins the cycle again. This lifestyle means that a female can have puppies on average every 3-4 years.

The males do not participate directly in the breeding of the offspring but indirectly keeping the territory of the female free from other males, therefore from potential dangers for the young and from competitors for food.


The adult brown bear has no natural enemies with the exception of the man with whom it collides as, being an omnivorous animal, it often approaches the outskirts of urban centers in search of food and therefore is killed either knowingly or involuntarily for example by cars.

Babies can easily be killed by mountain lions and wolves.


The brown bear is classified on the IUNC Red list among animals at low risk of extinction LEAST CONCERN (LC): it has in fact been estimated that its population is not in danger of extinction for the moment, being quite widespread. There are many small isolated populations that risk disappearing but vice versa, in many areas, thanks to adequate protection plans, they are expanding.

The world population is estimated at around 200,000 specimens of which about half are present in Russia while the remainder is found in the United States 33,000, Canada 25,000, Europe (excluding Russia) 14,000 and numerous small isolated populations especially in the southern areas.

An aspect to underline is that in many countries, where adequate population protection and control plans are not implemented, especially in eastern countries, it is an animal hunted for its gallbladder and legs. Furthermore, the same urbanization that advances, eliminates or fragments their natural habitats, dividing the population with serious consequences for reproduction. Unfortunately, it should also be noted that there are still nations that allow hunting for pure sport of this animal: Russia, Japan, Canada, Alaska, some countries of north-eastern Europe.

Today in many countries it is a protected species and also internationally they are animals protected by the CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) and registered in Annex I or Annex II (depending on the country).

It should be emphasized that, despite many countries adopting protection plans and allocating special protected areas to this large carnivore, these are insufficient in size to support a viable population.


It is an important animal in the ecosystem because, being a great user of fruit, it contributes to the dispersion of seeds and also because it helps to keep the populations of different species of insects under control.


The Marsican brown bear is widespread in Italy, Ursus arctos marsicanus, a subspecies that lives in the central Apennines, in an area between Umbria and Molise. Once it was widespread in all the Apennine areas, today it is relegated to the areas of the Abruzzo, Umbria and Molise National Park. Although it has been a protected species for many years, poaching continues on a population now reduced to 30-50 specimens (the estimate is not precise as there are no particularly reliable data).


To hear the noises emitted by this animal, go to the article: The sounds made by the brown bear.


  1. Withers: region of the body of the quadrupeds between the upper edge of the neck and the back and above the shoulders, in practice the highest part of the body (excluding the head);
  2. original photograph courtesy of U.S. Fish and Wildlife Service.

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