oso It belongs to the Ursidae family of large short-tailed carnivores that inhabit America, Europe and Asia.


There are eight different species of bears that can be found in a wide variety of habitats, both in the northern and southern hemispheres.

Subfamily: Ailuropodinae

  • Gender: Ailuropoda
    • giant panda (Ailuropoda melanoleuca)

Subfamily: Tremarctinae

  • Gender: Tremarctos
    • Spectacled bear (Tremarctos array)

Subfamily: Ursinae

  • Gender: Ursus
    • Sloth bear or sloth bear (Orsini bear)
    • Bear away (Ursus malayanus)
    • Tibetan Oso (Ursus thibetanus)
    • Black bear (American bear)
    • Polar Bear (Ursus maritimus)
    • Grizzly (Ursus arctos)
Oso grizzly
Oso grizzly


The bear varies in size and weight according to the species to which it belongs. He lonely bear (Helarctos malayanus) is the smallest of the species weighing less than 50 kg, and the largest is a subspecies of the Alaskan brown bear known as Very Kodiak (Ursus arctos Middendorffi).

The life span of bears in the wild varies from 15 to 30 years, but in captivity they can survive much longer.

The skull is elongated and very heavy at the back, and the jaws are controlled at the hinges by a set of powerful muscles. The lips are protrusible and mobile.

The teeth of omnivorous bears are not specialized. The initial three premolars are usually missing or very small. Except for the variation in the presence of premolars, the ursid dental formula is that of the carnivore in general, but the sloth lacks a pair of incisors in the upper part of the mouth. The shear teeth (carnassials) are poorly developed and the molars have wide, flat crowns.

Unlike cats and canids, such as dogs and wolves, the bear walks in a plantigrade way, that is, the sole of its foot and the heel touches the ground (similar to humans). The soles of the feet are hairless, except for the polar bear that has them covered with hair to allow it to walk on the ice firmly.

Each foot has five toes ending in large non-retractable claws, which in some species is adapted for burrowing, as in the Asian sloth bear. The front claws are more developed than the rear ones, and are adapted to dig up small rodents or plant roots.

They have an excellent sense of smell, and despite their size, they are excellent tree climbers, and swim very strongly. They are also capable of running up to 22 km / h for short periods of time.

Some species have special characteristics that help them better consume a certain food, such as asian sloth bear (Information System) that specializes in raiding and destroying termite nests, sucking them up with its funnel-shaped lips. He giant panda (Ailuropoda melanoleuca) has a bone formation in the forefoot that allows it to better manipulate bamboo.


Most bears are nocturnal and solitary animals, except in mating season where they gather to form pairs and mate in isolation.

They establish individual territories that vary in size depending on the amount of food available and larger areas are used when food is abundant. Territories are marked by rubbing against trees and other objects, thus spreading their scent. Some species mark with urine and a waxy substance from their anal glands. For example, American black bears travel between 40 - 200 km2 and grizzly bears between 300 - 400 km2. Some polar bears must travel up to 125.000 km2 to find food.

With the cold weather on, bears eat a large amount of food before entering a long period of deep sleep throughout the winter. Each species of bear has a certain way of wintering, for example, the polar bear digs a burrow in the snow, while the gray bears build large mounds of earth in front of their burrows.

Although they are known to hibernate, the weight gain causes most bears to sleep with great difficulty during much of the winter, so they do not really winter as they lack the physiological characteristics (lower heart rate, body temperature, respiratory rate and blood pressure) needed to actually hibernate.


To communicate they produce a series of vocal and non-vocal sounds. Tongue clicking, grunting, or chirping is performed in cordial situations, such as between mothers and calves or between spouses, while whining, tantrums, or blowing of air are performed when stressed.

In moments of alarm, barking is used to indicate or relieve the presence of an animal. Danger sounds consist of jaw clicks and lip clicks, while aggressive encounters produce tooth snapping, bellows, growls, roars, and pulsing sounds. Hatchlings squeal, cry, wail or yell when in distress and make motor whirring sounds when comfortable or nursing.

Bear exhibiting on two legs
Bear exhibiting on two legs

They also communicate through visual displays such as standing in order to intimidate the opponent by exaggerating their size. Chest markings in some species further contribute to intimidation. Individuals can approach each other by walking with stiff legs and head lowered. The dominant bear is manifested by a frontal orientation, showing the canine teeth, twisting of the muzzle and stretching of the neck. A subordinate may react with a lateral orientation, turning and lowering the head and sitting or lying down.


The bear lives in the temperate regions of the north and is found further north than any other mammal.

They can be found in a wide variety of habitats (depending on the species) including lowland humid tropical forest, both hardwood and coniferous forests, grasslands, steppes, mountainous grasslands, alpine boulders, arctic tundra and, in the case of the polar bear, ice floes.


The bear is distributed throughout the planet, present in sixty countries in the northern hemisphere concentrating on Asia, North America and Europe, with the exception of the spectacled bear that is native to South America in the Andean region. Africa and Australia are totally bearless.

The American black bear is restricted to North America, and the polar bear is restricted to the Arctic Sea.


The bear is classified as a carnivorous animalBut there are many species that have adapted to a herbivorous diet. For example, him giant panda (Ailuropoda melanoleuca) has a bamboo-based tooth and the polar bear is fully carnivorous.

Giant panda bear eating bamboo leaves
Giant panda bear eating bamboo leaves

They consume a wide variety of foods, although it will depend on the species. Despite being large, they can consume: ants, bees, tree seeds, roots, nuts, berries, insect larvae ... Many bears enjoy honey, so much so that when bear away (Helarctos malayanus) is nicknamed as the "honey bear."

As for meat, it consumes rodents, fish, deer, pigs and seals. The grizzlies bears (Ursus arctos) are known to be great salmon fishers. Most hunt fish above land animals, although it is not uncommon to see bears that do not eat any fish.


Due to its size, the bear has few natural enemies. Humans are the biggest predator of bears. Although sometimes, some can die of starvation by not accumulating enough fat to get through the winter.

The most vulnerable bears are young, due to their inexperience and their small size, and they can be victims of wolves or pumas, but above all, by other male bears. This reason makes the female highly protective animals with her young.


The bear is sexually mature between four and six years. Males tend to mature much later than females.

When it mates it does not play any role in the upbringing, since after mating it abandons it. They reproduce once a year and many species of bears only reproduce every two to four years. The breeding season is usually in late spring or early summer.

The gestation period is variable since the fertilized ovum remains dormant in the uterus to ensure that the young are born during the winter while the female is in the burrow and go outside in the spring, when food is abundant.

Bear cub
Bear cub

Newborn bears weigh about 500 grams and measure about 23 cm in length, from their nose to the tip of their short tail. Twins are very common, although they can have up to five young.

The young are fed for a few months, although most can fend for themselves after six months ... the females are very protective due to attacks by other predators, so they will stay with her for a whole year.

State of conservation

The bear is currently subjected to invasion of their habitats and illegal trade, including the Asian market for gall bears, although it is prohibited.

The IUCN has classified six species of bears as vulnerable animals, including two less worrisome species such as the brown bear and the American black bear, which are in danger of being extinct in certain regions. Both species live in areas where humans are not present and the unnatural houses of mortality are: hunting, capture, death on the road and predation.

Brown bear in a zoo
Brown bear in a zoo

To try to prevent the extinction of the bear, laws have been passed for its conservation that prevent the destruction of its habitats. These laws have been seen in a positive light around the world, as some people feel strongly identified with bears because of their similarities to humans (omnivorous diets, their ability to stand on two legs and their symbolic importance). It is hoped that with everyone's collaboration, the bear species will succeed.

Relationship with humans

The bear can be tamed quite easily if the training begins when they are young and they are used in circuses or in movies. This has made many people believe that bears are harmless and led to many tragedies for both of them.

The most dangerous bears for humans are brown and polar bears, although Eurasian brown bears and American black bears also attack. Asian and American black bears can sometimes attack livestock, destroy fruit or crops, such as corn.

Bear skins have been used to create different products such as: rugs or clothing. Meat is also eaten very often, especially that of black and polar bears. The claws and teeth are used by the Native Americans to create ornaments. The fat is used for cooking and from gallbladders are used for pharmaceutical purposes in Asia.

Popular culture

The Vikings believed that wearing a t-shirt made of bearskin would adopt the strength of the animal as strength or courage. Legend has it that the word "berserk" has its origin in this belief, due to the way in which men "affected" by the attributes of the bear behaved. Although it is unknown if it is 100% true.

The bear is also frequent in literature and in audiovisual filming, possibly the most famous is Winnie the Pooh, a bear who enjoys eating honey and living with other animals.

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