The grizzly (Ursus arctos) is a placental mammal that is part of the Ursidae family. The coloration of the hairs on the back is dark brown, almost black. However, this may vary depending on the region where you live. Thus, in India the coat is reddish with some silver tones.
It is native to the northeast region of North America, in addition to Asia and Europe. The preferred habitat is wet meadows, tundras, and low elevation riparian areas. One characteristic that identifies it is its claws. These are curved and large, especially on the front legs. The brown bear, as it is also known, uses them to excavate the earth and reach the roots to eat them thanks to its powerful jaws.
The vast majority of the time, this mammal digs its own burrow and makes a bed out of dry vegetation. This is usually located on a slope, either between the roots of a large tree or under a huge stone. This shelter can be reused year after year.
The Ursus arctos It is omnivorous and feeds on salmon, trout, ungulates, elk, fruits, ants, birds, berries and carrion.
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The brown bear begins a period of inactivity in the month of October until December. The exact period in which it occurs is influenced by the climate, location, and organic condition of the animal..
In southern regions, this phase may not occur and if it does, its duration is very short. During this stage, the bear enters a deep sleep, in which the temperature of the animal's body drops a few degrees.
Some specialists state that it is not a true hibernation, but an inactive period, since bears can easily wake up from the sleep in which they are.
The Ursidae family originated in Europe, in the early Miocene, about 20 million years ago. The predecessor is the Ursavus elemensis, an extinct species that was similar in size to a dog, although it had bear characteristics such as teeth. Later they suffered adaptations, such as the reduction of the carnassials and the expansion of the biting surface of the molars.
Of Ursus elemensis, First, the giant panda is derived and later the spectacled bear. Then there was a polytypic divergence in several species, among which is the Ursus arctos.
According to research, the brown bear evolved from Ursus savinis, that inhabited Asia 800,000 years ago. The Ursus arctos arrived in Europe approximately 250,000 years ago and shortly thereafter north of the African continent.
The species entered Alaska 100,000 years ago, although they did not migrate south until 13,000 years ago. Specialists believe that the mobilization to the south occurred at the time when the short-nosed bear (Arctodus simus) became extinct.
The fur of the brown bear is thick and long, with a long mane located at the back of the neck. This can have variations in each of the species.
During winter, it is long and thick, and can measure between 11 and 12 centimeters long. In addition, it is thin and very rough to the touch. In the summer, the hair is scarce and much shorter, aspects that vary according to the geography where it lives.
Despite being known as brown bears, these animals are not completely brown. The tones may vary according to the habitat where it is found.
Thus, in China, they have a whitish or yellowish stripe around the neck and shoulders, while in India they are reddish, with spiky hairs in silver tones..
Even within the subspecies, there can be various shades of brown. For example, those that live in North America can have a wide range of colors, ranging from a coat so dark brown, that they appear black, to a cream or yellowish brown hue..
The legs are generally large and dark in color, with the end lighter. The rear ones are 21 to 36 centimeters in length, while the front ones can be up to 40% smaller. The width of this limb is around 17.5 to 20 centimeters.
The claws of the Ursus arctos They are curved and large, the front legs being much longer than the back ones. The length is between 5 and 6 centimeters, and can reach up to 10 centimeters, if the length of the curve is considered.
Due to this particular structure of the claws, added to its excessive weight, when this animal is in the adult stage it is very difficult for them to climb the trees.
The brown bear is a plantigrade animal, which tends to use running walks more frequently than trotting. While walking, this mammal moves at a slow or moderate speed.
According to research carried out, where the factors involved in these movements were evaluated, the reaction force on the ground was more pronounced in the hind legs. Likewise, the speed of force development is notably higher for the rear extremities than for the front ones..
The brown bear, as this species is also known, is the only one within the genus Ursus that has a kind of hump on the upper part of the shoulder. This is a muscle type training.
This characteristic is an adaptation that allows it to have more strength while digging, a typical activity during foraging. Also, thanks to his strong muscles, he can mobilize large amounts of earth that he makes to build his resting place..
The adult species has a large skull, compared to its body. Its shape is concave and the area of the forehead is wide, raised abruptly. As for the base of the brain, it is elongated and small.
There are geographic variations in terms of the dimensions and characteristics of this bone structure. For example, North American brown bears have flatter profiles than coastal and European ones..
Ursus arctos It has very strong teeth: the incisors are large and the lower canines are strongly curved. In relation to the molars, the first three of the upper jaw are underdeveloped and have a crowned root. These teeth are usually lost at an early age.
In the maxilla, the second molar is smaller than the rest and in the adult it may be absent.
The physical dimensions of the brown bear, in terms of the length of its body, is 1.4 to 2.8 meters. As for the tail, it is short, with a length of 6 to 22 centimeters. On average, the weight of adult males is 217 kilograms and that of females 152 kilograms.
When it rises on its two legs, a posture that it occasionally assumes, the Ursus arctos can measure between 1.83 and 2.75 meters.
This is the species that has the most variations in size, among all modern bears. This could depend on the population where you live and also on the seasons. Thus, in the spring it tends to weigh less, due to the lack of food during the inactivity period..
In late autumn he gains weight after a period of hyperphagia in preparation for hibernation.
On the other hand, those that live in northern Europe weigh between 115 and 360 kilograms, while those that live in the south can weigh between 55 and 175 kilograms. Environmental conditions are probably determining factors in these weight variations.
The Ursus arctos it is the ursid with the widest distribution. Previously it was only found in several territories in western North America, including northern Mexico. They then spread throughout Asia, Europe, North Africa, and the Middle East..
Today, this species occupies northeastern North America, Europe, and much of northern Asia. Most of the population is in Canada and Alaska.
In some areas of Europe, North America and southern Asia, these bears are found in small groups, which may even be isolated. Grizzly bears can be found with some regularity in Switzerland, probably coming from a reintroduced group that lives in northern Italy..
The same is true in Lithuania, where the animals found there probably come from Belarus and Latvia. However, due to the irregularity of their presentation, these countries are not considered as home ranges of this species..
Canada has a stable population, extending throughout the Yukon, British Columbia, the Northeast Territories, and much of Alberta..
In relation to the United States, about 95% of the Ursus arctos they are in Alaska. In the lower states, almost 98% have disappeared from their natural habitat. However, its population is gradually growing in the great western plains and in the Rocky Mountains..
The largest population, among the lower 48 states, is found in Yellowstone and the northern continental divide ecosystem..
In these states there are five major ecosystems: the Yellowstone (Wyoming), the Northern Continental Divide (northeast of Montana), the Cabinet-Yaak (Idaho and Montana) and the Selkirk Ecosystem (Washington and Idaho).
Unfortunately, the populations that live there are isolated. This results in low genetic diversity and the inhibition of gene flow among grizzly bears that live in these ecosystems..
In Europe, populations are fragmented. It is located from the Iberian Peninsula to Russia and Scandinavia. This species is extinct in the British Isles and highly threatened in Spain, France and in certain areas of Central Europe..
In Spain he lives in Cantabria, Asturias, Galicia and León. A small group lives in the central region of Italy, in the Apennine Mountains, Lazio and Abruzzo.
Among the countries with the largest population, in eastern Europe, are Romania, Bulgaria, Slovenia and Greece. In the north, they are distributed in Sweden, Finland, Estonia, Norway and Croatia. They also live in Bosnia and Herzegovina, North Macedonia, Serbia, Greece, Montenegro, Bulgaria and Albania.
In this region, the brown bear is found from Georgia, Azerbaijan and Armenia, through Turkey. It is also north of Iraq, into Kazakhstan, Uzbekistan and north to Kyrgyzstan. In these nations, populations are fragmented and very small, so they run the risk of being isolated at the genetic level.
In Russia it is spread over almost the entire territory. It is also located in China, North Korea, Pakistan, India, and Afghanistan. After Russia, the Japanese island of Hokkaido has the largest number of brown bears.
The brown bear occupies a variety of habitats, ranging from ice fields and mountain forests to desert areas. In North America, it lives in open areas, such as alpine meadows, tundras, and coastlines.
This species has a very varied habitat, with no apparent altitude preference. Thus, it can live from sea level to a height of 5000 meters, as in the Himalayas..
Over much of its range, the Ursus arctos it slopes towards the semi-open fields, with dense vegetation, which allows you to have a place to rest during the day. Also, it is found in a great diversity of temperate forests, estuaries, black pine forests and fir trees..
In western Eurasia, the brown bear lives in the mountainous forests of the Alps, the Caucasus, and the Pyrenees. In Eastern Russia, specifically Siberia, this species lives in extensive pine forests, in waterways or in poorly drained swamps..
In relation to Japan, on Hokkaido Island it lives in mixed forests, where broad-leaved trees predominate, such as the Fagus sylvatica.
The brown bear population has declined, even facing local extinctions. This has happened in Denmark, Egypt, Belgium, Mexico, Israel, Monaco, Ireland, Morocco, Libya and Switzerland, among others..
However, the IUCN considers it as a species with a low possibility of extinction. As in turn, said organism highlights the importance of taking actions aimed at reducing the threats that afflict this animal, in order to guarantee its survival..
Beyond the geographic problem, where population isolation hinders genetic exchange and affects reproductive success, there are other threats to this species such as:
The gestation period of the female lasts for 12 months. After this, between 1 and 3 young could be born, which remain next to the mother for about a year and a half. Thus, the interval between deliveries could be every two years, which represents a low birth rate..
Because of this, the population cannot grow rapidly, thus preventing it from increasing the number of bears required to counteract the decline..
The habitat where the brown bear develops is being affected by the actions carried out by man, such as the felling of trees, the construction of roads and urban planning and the development of hydroelectric plants, among others..
The forests where it lives are deforested, sometimes causing this animal to descend from the mountains to rural areas, in search of food that is scarce in its natural environment.
In relation to land communication routes, roads not only divide the territory, but also constitute a danger, when the animal suddenly tries to cross the road..
The brown bear is poached due to the commercialization of some parts of its body, such as the gallbladder and legs. In some regions of Alaska, this animal is killed to increase the populations of caribou and elk, for the benefit of hunters.
Actions to protect the Ursus arctos they may vary in each nation where you live. In those where they abound, such as Russia, Canada and Alaska, they are legally hunted. However, the regulations are designed to ensure a sustainable number of populations..
The vast majority of groups of brown bears are protected by national legislation and international agreements. Furthermore, in certain countries of the European Union, trade in bear products is restricted.
Animal Kingdom.
Subkingdom: Bilateria.
Phylum: Chordate.
Subfilum: Vertebrate.
Superclass: Tetrapoda.
Class: Mammal.
Subclass: Theria.
Infraclass: Eutheria.
Order: Carnivora.
Suborder: Caniformia.
Family: Ursidae.
Genus: Ursus.
Species: Ursus arctos.
Subspecies:
Ursus arctos alascensis.
Ursus arctos californicus.
Ursus arctos arctos Linnaeus.
Ursus arctos beringianus.
Ursus arctos dalli.
Ursus arctos collaris.
Ursus arctos crowtheri.
Ursus arctos isabellinus.
Ursus arctos gyas.
Ursus arctos horribilis.
Ursus arctos pruinosus.
Ursus arctos lasiotus.
Ursus arctos middendorffi.
Ursus arctos syriacus.
Ursus arctos sitkensis.
Ursus arctos stikeenensis.
The female sexually matures between four and eight years of age, while the male usually between five and nine years. It needs to be big and strong enough to compete with other males for the right to mate..
The males have large territories, which makes it very difficult for them to detect their possible mates. This is why when the female is ready to have a mate, she excretes a scent that the male can pick up from a distance..
Males will do their best to mate with as many females as they can. The Ursus arctos can be with the same partner from a few days before mating to two weeks after.
Outside of that time, females and males do not show any sexual interest between them..
Once the egg is fertilized, it does not implant immediately, as it does in many mammals. The females of this species have a delay in implantation, so the fertilized ovum does not attach itself to the uterus for its development until some time before the period of inactivity..
If the female is not well nourished during her hibernation, she could spontaneously expel the fertilized egg. Prolactin, a hormone related to the gestation process, is controlled by photoperiod. This chemical has a great influence on the reactivation of the corpus luteum..
When the egg has already attached itself to the walls of the uterus, the gestation period lasts for 6 to 8 weeks. After this, between one and three cubs are born.
The brown bear is omnivorous and eats a wide variety of foods. The diet varies throughout the geography and also depends on the seasons.
For example, during the spring, the bases of their diet are shoots, grasses and sedges. In the fall and summer, berries and fruits become important.
In terms of dietary variability, in Yellowstone National Park, in the western United States, meat consumption accounts for almost 51% of food. In contrast, in Glacier National Park to the north, animal intake was only about 11%.
With reference to this diversity, in some regions of the interior of North America, the diet of the Ursus arctos is between 80 and 90% herbal.
As for the plant material it eats, there are mountain ash (Sorbus sitchensis), White hawthorn (Crataegus spp.), blueberry (Symphoricarpos spp.), honeysuckle (Lonicera spp.), pine (Pinaceae) and willow (Salix spp.).
Besides these there is also the dandelion (Taraxacum spp.), blueberry (Vaccinium spp.), clover (Trifolium spp.), grassHeracleum spp.), horse tail (Equisetum spp.), Strawberry (Fragaria spp.) and thistleCirsium spp.).
To obtain beetles, worms and insects, the brown bear searches for nests, although it could also dig in the ground. In Eurasia, wasps and honey bees are consumed to a high degree.
Other insects that make up their diet are ants and ladybird beetles. Those who live along the beaches, dig for clams and crabs.
Brown bears feed mainly on trout, belonging to the genus Oncorhynchus. They also eat pink salmon (O. gorbuscha) and sockeye salmon (O. nerka).
Likewise, in Canada they hunt broad white fish Coregonus nasus Y Catostomus catostomus. In Siberia, they prefer the northern pike (Esox lucius) and take it (Thymallus thymallus).
In addition to the predation of salmon, the vast majority of the Ursus arctos they are not active predators. However, they have the ability to capture anything from rodents to ferocious tigers or large bison. According to the work carried out, the prey consumed comes largely from carrion theft.
Among the mammals that make up their diet are hares (Lepus ssp.), marmots (Marmot ssp.), pikas (Ochotona ssp.), mice, ground squirrels and rats. They also eat Himalayan marmots (Himalayan marmot), beavers (Castor spp.) and North American porcupines (Erethizon dorsatum).
Among the ungulates are bison and deer, with Canadian deer (Cervus canadensis), caribou (Rangifer tarandus) and the moose (Moose moose) your favorites.
The Ursus arctos can eat birds and their eggs. Among the species are Aleutian tern (Onychoprion aleuticus), whooper and trumpeter swans (C. cygnus Y Cygnus buccinator), ducks and golden eagles (Aquila chrysaetos), among others.
The Ursus arctos may be active at various times of the day, but they usually forage for food in the morning and at night, resting in a dense canopy, after doing this activity.
Frequently makes seasonal movements, traveling several kilometers in the fall to access areas with greater food availability, such as those with salmon streams.
Occasionally, it can form large groupings, where there are hierarchical positions. These are usually established and maintained aggressively.
Dominance against another male is demonstrated by showing the canines, twisting the muzzle and stretching the neck. During combat, the brown bear uses its paws to hit the opponent on the shoulders or neck and thus be able to bite him on the head.
Large adult males have the highest rank, while those with the lowest rank are adolescents. Females often rival males, and they are the only ones who establish a bond with their young.
To get around, you do so with a slow, heavy walk, although you may also move quickly. Its behavior is terrestrial, but it can swim and hunt in water.
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