Beaver (photo): Tireless dam builder. Beavers are hardworking river engineers

, Glires) - a genus of mammals from the order of rodents, distinguished by a wide, horizontally flattened and scaled tail and the fact that the toes on the hind legs are connected to each other by a swimming membrane.

The red-brown incisors are very strongly developed and protrude significantly outward; the upper two with a wedge-shaped crown; the molars, of which there are eight in each jaw, namely four on each side of the upper and lower jaws, are provided with projections of enamel. The legs are short, five-toed; on the second toe of the hind legs there is a double claw. Only one species is known: the beaver river, or ordinary (S. Fiber), resembling a badger in size and awkward body shape, having 80-90 sant. and longer, so it is one of the largest rodents. B. is reddish-brown or blackish in color above, lighter below, white, yellow or spotted varieties are also found; the tail is brown-black. Its body is thick, laterally compressed; the back, especially during rest, is convex. The head is rounded and pointed at the front, resembling the head of a rat; the ears are very small and almost completely hidden in the fur; the eyes are located on the sides of the head, small, with a dark blue rim and a vertical pupil; the nose is wide and bare, with big nostrils, which can be closed. The neck is short and thick. The wide and flat tail is covered with hair at the base, and the rest with scales, between which there are single hairs. Currently, B. lives in communities along the banks of large rivers in North America, Siberia and European Russia (on the Vistula), and occasionally occurs alone along big rivers Western Europe (Rhone, Elbe, Rhine, Vistula). Previously, B. was found much further south, for example, in Western Asia - on the river. Euphrates and even in India; now, as a result of intensified persecution, this animal is becoming rarer and rarer even in the North, especially in North America, although up to 150,000 skins are still traded annually from this country, each with an average price of 4-5 rubles. ser.

B. feeds on young shoots, bark and roots of trees. It moves awkwardly on the ground, but swims and dives well. The most remarkable feature of B. is their house-building and social life, about which, however, many exaggerated and implausible things are often told. To protect from the winter cold and from the pressure of water, B. buildings are erected; if the strength of one individual is not enough for this purpose, then the work is performed by the whole society. They erect artless, bluntly cone-shaped structures consisting of layers of branches, grasses, silt and stones and protruding 1.50-1.60 m above the surface of the water. The building is erected in two floors: the upper dry one, located above the water, serves as housing, and the lower one is underwater, for storing vital supplies. The lower floor has an exit located under water. In still water, beavers begin building directly, without any preparatory work, but in flowing water they first build a dam to keep the water at the same height. These dams are made of poles, the spaces between which are filled with stones and silt; At the base, such dams are from 3 to 4 meters wide and are sometimes built over a fairly significant length. The wood needed for buildings is obtained by gnawing with teeth the trunks of bushes and even fairly thick trees growing along the banks; their teeth are so strong that they can immediately bite through a branch an inch thick. In addition to cone-shaped water dwellings, in which 2-3 families usually live together, B. always have burrows located near the shore and with access to the water. If their construction is interfered with, they live in these holes; in the same way, they settle in such burrows even when they live alone. With the approach of cold weather, B. gather in large number and begin to repair old dwellings, and, if necessary, to build new ones. B. lives in groups only in the winter, and in the summer he spends most of his time alone. The beaver is very shy and comes out of its dwellings only at night. The female annually lays 2-5 blind, but fur-covered cubs, which she takes great care of. Young beavers separate from their parents only in the third year of life. B. lives 30-40, even 50 years. He is harmful in that he spoils the trees around his home, but this harm is more than compensated for by the benefits that he brings. B. is hunted partly for his valuable fur with a thick undercoat and a long, shiny edge, and partly for the sake of beaver stream, a substance with a peculiar penetrating odor that is used in medicine. This substance is secreted in two bags located on the sides of the anus. Previously it was also used in medicine oily beaver substance (Pinguedo or Axungia Castorei), placed in 2 oil bags located on the side of the beaver bags and under them. River beaver fur is very beautiful and good for fur coats. The undercoat of the beaver, which is used for making hats, is also of great commercial importance and can yield up to 1 ½ pounds from one good beaver skin. The skins of B., living alone in coastal burrows, are very worn out and are of little value; Only B., living in societies, provide beautiful furs and good undercoat, but their summer skins are much worse than winter ones. The latter are always fluffier and have thicker and darker hair.

From the river, or real, beaver, two animals should be distinguished, also called beavers, but having nothing in common with it: the beaver swamp (Myopotamus coipus, see Swamp beaver), belonging to the order of rodents, and beaver sea (Enhydris marina, see Sea otter), belonging to the order of carnivores, namely to the family thin, or martens (Gracilla s. Mustelina).

The article reproduces material from the Great Encyclopedic Dictionary of Brockhaus and Efron.

Beaver,

1 ) (Castor), mammal, genus of rodents. The beaver's body is clumsy, its tail is flattened on top and covered with scales, its legs are short, five-toed, and its hind toes have a swimming membrane. Beavers live in small colonies in middle lane(between 39° and 68° N latitude) Northern Hemisphere. They are famous for their amazing dams and dwellings; For the most part, these buildings are built jointly by the entire colony. Typically, dwellings have the appearance of a regular heap up to 3 m in height, built in two floors: the upper one is dry, used for housing, and the lower one, underwater, stores supplies; from it there is an outlet under the water. In order to ensure that the exit is always closed with water, B. build dams across the river from chewed tree trunks and branches, filling the gaps with silt and stones. Dams can be up to 4 m wide and several tens of m long. Branches, tree trunks or stones are also used to build a home. The living area of ​​each building is divided between 2-3 families; In summer, beavers spend most of their time alone. Growing young B. usually stay in the family for up to 3 years. The lifespan of beavers is up to 50 years. Beavers are hunted for their fur, which is highly prized. Its color is chestnut-brown. Most furs are mined in Canada and Siberia. There are 2 known species: European beaver, or river beaver ( C. fiber), up to 95 cm in length. IN lately it has been exterminated almost everywhere, but is partially preserved in the West and North-West. USSR, in the Central Black Earth Region, as well as in some places in Western Europe - along the rivers: Elbe, Danube, Rhone, and in the West. Siberia. The Canadian beaver differs little from the European one; lives east of the river. Missouri. In addition to fur, beavers are valued for their meat (the tail is considered a special delicacy) and for a special substance - beaver stream (see), used in medicine.

2 ) Swamp beaver ( Myocastor coypu), or coipu. Family rodent eight-toothed, body 45-90 cm long. The fur is black-yellow-brown, thick and soft, highly valued. Meat is eaten. Lives in Yuzh. America.

Literature:

• Ognev S.I., Vertebrates of the Voronezh province, M., 1923;
• Keppen F.P., On the previous and current distribution of the beaver within Russia, St. Petersburg, 1902;
• Charlemagne, News about bob-piv", "Ukrainsk. willing and fisherman”, No. 10, 1925 (with detailed bibliography).

N.B., N.D

The article reproduces text from the Small Soviet Encyclopedia.

Beaver (mammal of the rodent order).

Beaver (Castor fiber), a mammal of the rodent order. B. well adapted to semi-aquatic image life. Body length up to 100 cm, tail - up to 30 cm; weighs up to 30 kg. The tail is flattened from top to bottom, up to 15 cm, almost hairless, covered with large horny scutes. The toes on the hind limbs are connected by a wide membrane. It has valuable fur, which consists of shiny coarse guard hairs and very thick silky underfur. The color ranges from light chestnut to dark brown, sometimes black (melanism). In the early historical time B. was distributed throughout most of Europe, southern Siberia and part of Central Asia, as well as almost all of North America (American B., apparently, special kind C. canadensis).

Beavers are a genus of mammals of the rodent order, which includes two species: the common beaver (Castor fiber), a resident Atlantic coast to the Baikal region and Mongolia, and the Canadian beaver (Castor canadensis), found in North America.

The beaver's body weight is about 30 kg, its body length reaches 1-1.5 m, females are usually slightly larger in size than males. The rodent has a blunt muzzle, small ears, short, strong legs with powerful claws. The beaver's fur consists of two layers: on top there are hard red-brown guard hairs, and underneath there is a thick gray undercoat that protects the beaver from hypothermia. The tail is bare, black, flattened and wide, covered with scales. Near the base of the tail are two glands that produce an odorous substance known as “beaver squirt.”

Beavers are herbivorous rodents. Their diet includes the bark and shoots of trees (aspen, willow, poplar, birch), and a variety of herbaceous plants (water lily, egg capsule, iris, cattail, reed). They can also feed on hazel, linden, elm, and bird cherry. They readily eat acorns. Large teeth and a strong bite help beavers to eat fairly solid plant foods, and the microflora of their intestinal tract digests cellulose foods well.

The daily required amount of food reaches 20% of a beaver's weight.

IN summer period Beavers' diet is dominated by herbaceous food; in the fall, rodents actively prepare woody food for the winter. Each family stores 60-70 m3 of wood. Beavers leave their reserves in the water, where they retain their food quality until the end of winter.

Until the twentieth century, beavers were very widespread, but due to their mass extermination, their habitat has recently decreased significantly. The common beaver is found in Europe, Russia, China and Mongolia. Its closest relative, the Canadian beaver, lives in North America.

Common Beaver Species

The body length is 1-1.3 m, height is about 35.5 cm, weight is in the range of 30-32 kg. The body is squat, the paws are shortened with five fingers, the hind legs are stronger than the front ones. Swimming membranes are located between the fingers. The claws are strong and flat. The tail is paddle-shaped, flat, reaches 30 cm in length and 10-13 cm in width. The tail is pubescent only at the base, the rest of its surface is covered with horny scutes. The eyes are small, the ears are wide, short, and slightly protrude above the fur. Under water, the ears and nostrils close, and the eyes have special nictitating membranes. The common beaver has beautiful fur made up of coarse guard hairs and a thick, silky undercoat. The coat color ranges from light chestnut to dark brown, sometimes black. The tail and paws are black. Molting occurs once a year.

In the anal area there are paired glands, wen and the so-called “beaver stream”, the smell of which is a guide for other beavers, as it informs about the border of the family’s territory.

The common beaver is distributed in Europe (Scandinavian countries, France, Germany, Poland, Belarus, Ukraine), Russia, Mongolia and China.

Body length 90-117 cm; weight about 32 kg. The body is round, the chest is wide, the head is short with large dark ears and bulging eyes. The coat color is reddish or blackish brown. Tail length 20-25 cm, width 13-15 cm, oval shape, pointed end, surface covered with black horny scutes.

The species is distributed in North America, Alaska, Canada, USA, and Mexico. It was introduced to the Scandinavian countries and Russia.

Sexual dimorphism in beavers is weakly expressed, females are slightly larger in size than males.

Beavers usually live along the banks of forest rivers, streams and lakes. They do not live on wide and fast rivers, as well as reservoirs that freeze to the bottom in winter. For these rodents, tree and shrub vegetation along the banks of reservoirs and an abundance of aquatic and coastal herbaceous vegetation are important. In suitable places, they build dams from fallen trees, construct canals, and use them to float logs to the dam.

Beavers have two types of housing: a burrow and a hut. The huts look like floating islands made of a mixture of brushwood and mud, their height is 1-3 meters, their diameter is up to 10 m, the entrance is located under water. Beavers spend the night in such huts, store food for the winter, and hide from predators.

Beavers dig burrows on steep and steep banks, these are complex labyrinths with 4-5 entrances. The walls and ceiling are leveled and compacted. Inside, at a depth of up to 1 m, a living chamber is arranged up to 1 width and height 40-50 cm. The floor is located 20 cm above the water level.

Beavers are excellent swimmers and divers; they can stay under water for 10-15 minutes and swim up to 750 m during this time.

Beavers live either alone or in families of 5-8 individuals. The same family has occupied their plot for many years. Beavers do not walk 200 m from water. Rodents mark the boundaries of their territory with a beaver stream.

The main periods of beaver activity are night and twilight.

Beavers are monogamous rodents. Breeding occurs once a year. The mating season begins in mid-January and lasts until the end of February. Pregnancy lasts 105-107 days. One litter contains 1-6 cubs, which are born in April-May. Babies are born semi-sighted, well-furred, and their weight is approximately 0.45 kg. After a few days they can already swim. The female teaches them to swim, pushing them out of the hut into the underwater corridor. At 3-4 weeks, the beaver cubs begin to eat leaves and stems of grass, and until 3 months the mother feeds them with milk. The young live with their parents until they are two years old, after which they reach puberty and begin an independent life.

In captivity, the life expectancy of beavers is up to 35 years, in the wild it is 10-17 years.

Natural enemies

The natural enemies of the river beaver are wolves, brown bears and foxes, but the greatest damage to the population of this species is caused by humans, exterminating beavers for their valuable fur and meat.

• The common beaver is the largest rodent in Europe and the second largest in the world after.
• The word "beaver" comes from the Indo-European language and is an incomplete duplication of the name brown.
• Until the middle of the 20th century, beaver fur was very popular in America, Europe and Russia, which is why the population of these animals decreased noticeably: there were 6-8 isolated populations of 1200 individuals left. To preserve the species, beaver hunting was prohibited. Currently, the common beaver has a minimal risk status, and the main threats to it are land reclamation activities, water pollution and hydroelectric power plants.
• In addition to beautiful and durable fur, beavers are a source of beaver stream, which is used in perfumery and medicine. Beaver meat is also edible, but may contain salmonellosis pathogens. According to church canons, it is considered fasting.
• In 2006, a beaver sculpture was unveiled in the city of Bobruisk (Belarus). There are also sculptures of this rodent in the Alpine Zoo (Innsbruck, Austria).

Description of the animal.

The river beaver is the largest rodent in the fauna of Russia. Large specimens of beaver reach a length with a tail of about 125 cm and a body weight of 25-30 kg. The beaver's body is massive, rather awkward and baggy. The front and hind paws each have five toes, with the hind paws being much larger and equipped with a swimming membrane, while on the front paws it is only rudimentary. The toes are equipped with strong, large claws that are adapted for digging the ground. The beaver's tail is very original: more or less rounded at the base, it is strongly flattened horizontally in the middle and final part and is completely covered with horny scales, between which there are sparse hairs. The head is large, round and with a blunt muzzle. The ears are small, covered with hair; when diving, the auditory opening can close. The eyes are small with a vertical pupil and have a third eyelid, or nictitating membrane, which, being transparent and covering the eyes when diving, protects them from the direct action of water on them, without at the same time depriving them of the ability to see surrounding objects under water. Upper lip it is bifurcated and in the section of the lips very strongly developed, powerful, chisel-shaped, orange-colored incisors are visible.

In the groin area of ​​beavers there are paired glands that secrete a good-smelling, oily, brownish liquid called “beaver stream.” The fur is very thick, with a fluffy undercoat and a shiny, rough coat. The color of beaver fur varies from reddish-brown to almost black.

Lifestyle.

In their lives, river beavers are closely connected with water, although they spend most of their time outside it, but never settle far from water. Their habitat is forest rivers, river backwaters and forest lakes.

Beavers are social animals and usually settle in colonies close to each other where they are not disturbed. They live either in burrows or in “huts”. Beavers are excellent builders; their structures can be very complex. Beaver seas are quite long and complex. One of the entrances to the burrow is always placed under water, and one or more others open onto land. There are large burrows that have several underwater and land exits. In the depths of the hole there is a nesting chamber lined with finely gnawed bark and tree wood. In places where the banks are not suitable for digging holes, beavers build “huts.” These “huts” are of considerable size, reaching several meters in diameter and more than one and a half meters in height. These structures have the appearance of a conical dugout made from stumps of branches and trunks of thin trees, held together by silt, earth and aquatic plants. The “hut” usually has several entrances located under water, and above the water level there is a large living chamber. To ensure that the exits from the hut or hole are always under water, beavers collectively build dams that serve to raise the water level, and for this they often use large trees, up to 50-60 cm thick, skillfully cutting them with their powerful incisors, dumping them in the water and floating them to the site of the dam's construction. However, such dams are built only where beavers live in large colonies and where they are little disturbed.

In the water river beaver swims and dives beautifully, but on land it moves awkwardly, slowly, waddling, dragging not only its tail, but also its thick belly.

Beavers lead night look life. During the day, as a rule, they are in the hole and only at dusk, leaving their shelter, they begin to work and feed. A beaver spooked on the water strikes it forcefully with its tail, making a characteristic splash, and dives deeply, appearing again at a great distance.

Nutrition.

Beavers feed only on plant foods. The basis of their diet is the bark and young branches of trees with soft wood, such as willow, willow, aspen, poplar, and in the north also birch (but in no case alder). In addition, beavers eat some of the herbaceous aquatic plants and especially their succulent and fleshy roots and rhizomes.

Wintering.

In winter, beavers do not hibernate, but they rarely come to the surface of the earth - only during thaws. All beaver activity in winter takes place in a hole or hut and under the ice of a reservoir. For the winter, beavers make large supplies of food for themselves from twigs and branches, which they store by strengthening them at the bottom of reservoirs near the entrance to their homes.

Reproduction.

Beavers breed once a year. Their estrus occurs in late winter and early spring, and its duration is quite extended - from January to March. The gestation period is 105-107 days. The number of young in a litter is usually from 2 to 4. The young are born already covered with hair, with with open eyes and develop very quickly, a few days after birth they are able to swim, but they do not move on to independent life so quickly. The beaver is a very gentle mother and continues to care for the young even after finishing milk feeding, which lasts about two months. Beavers reach sexual maturity at the age of three.

Beavers change their hair coat, like many other semi-aquatic animals, continuously, without pronounced periods of molting, but its intensity increases in spring and autumn. The river beaver, as has been said, is a very gifted animal, as evidenced by its remarkable building and social instincts. In captivity, it is perfectly tamed and exhibits good memory and attachment to a person. Due to their hidden semi-aquatic lifestyle, beavers have few enemies among animals and birds. In winter, a beaver can become a victim, and, but this happens relatively rarely. Its most dangerous enemy is the otter, which often attacks young beavers.

Economic importance.

Beaver fur is extremely valuable and ranks among the first in terms of price among the furs of animals all over the world. Its value is determined by its beauty and very high durability in wear. In addition to fur, beavers produce valuable “beaver stream”, extracted from the inguinal glands. “Beaver stream” has a strong pleasant odor and is used in medicine as an aphrodisiac and tonic, and in the perfume industry as an aromatic product.

In foreign trade ancient Rus' beaver fur played a very important role, and only the predatory capitalist economy negated the commercial significance of the beaver not only in our country, but also in Western Europe and North America.

A short message about the beaver will tell you what they eat, where they live and how these animals build. A story about beavers for children can be supplemented with interesting facts.

Brief message about beavers

The beaver is a fairly large rodent mammal, known as a dam builder. Distributed in North America and Eurasia on the banks of forest rivers, streams and lakes. They build dams and dams from fallen trees, causing the water level in the dams they create to rise.

Description of the beaver for children

The beaver is a rather large rodent, its weight can reach up to 32 kilograms. Body length is about a meter. He has valuable fur, however, there is no fur on his tail, instead there are scales. When a rodent swims, its fur does not get wet, and it does not freeze in the water. The tail is interestingly designed; it helps the beaver to “steer.”

The animal can spend up to fifteen minutes under water. It has swimming membranes on its paws, thanks to which the animal reaches speeds of up to ten kilometers per hour. There are also sharp claws on the front paws. The rodent's teeth, especially the four front incisors, are sharp; they are real tools and act like a saw.

The beaver family consists of several individuals, about five in total, but they can also live alone. In the fall, beavers work a lot, and in the summer - much less. In winter, they do not leave their homes at all, especially when it is cold.

Beaver lifespan- about 20 years in captivity, in nature - about 15 years.

What do beavers eat?

Beavers feed on the bark and young branches of trees that are specially felled for this purpose, gnawing at the base. But for the winter we have to make preparations: animals hide tree bark under water.

Beavers love to build. As soon as they like the area somewhere, they immediately begin to build. And definitely near water. The fact is that animals feel calm and safer in water than on land.

These water-loving animals can build burrows and huts. In both constructive option the exit from the home is under water.

The beaver liked the steep bank - he digs a hole. And if the shore is flat, then the animal builds a hut from branches, sticks, twigs; the animal uses clay and silt as a cementing mortar for the structure.

The common beaver, or river beaver, is a semi-aquatic mammal of the rodent order; one of two living members of the beaver family (along with the Canadian beaver, which was previously considered a subspecies). The largest rodent of the Old World fauna and the second largest rodent after the capybara.

The word “beaver” is inherited from the Proto-Indo-European language (cf. German Biber; German Bebros), formed by incomplete doubling of the name for the color brown. Reconstructed base *bhe-bhru-. According to authoritative linguistic sources, the word beaver should be used in the meaning of an animal from the order of rodents with valuable fur, and beaver - in the meaning of the fur of this animal: beaver collar, clothing with beaver fur. However, in spoken language the word beaver is widely used as a synonym for beaver (like fox and vixen, ferret and polecat).

Appearance

The beaver is a large rodent adapted to a semi-aquatic lifestyle. The length of its body reaches 1-1.3 m, the height at the shoulder is up to 35.5 cm, and the weight is up to 30-32 kg. Sexual dimorphism is weakly expressed, females are larger. The beaver's body is squat, with shortened 5-toed limbs; the rear ones are much stronger than the front ones. Between the toes there are swimming membranes, strongly developed on the hind limbs and weakly developed on the forelimbs. The claws on the paws are strong and flattened. The claw of the second toe of the hind limbs is forked - the beaver combs its fur with it. The tail is oar-shaped, strongly flattened from top to bottom; its length is up to 30 cm, width - 10-13 cm. The tail has hair only at its base. Most of it is covered with large horny scutes, between which sparse, short and stiff hairs grow. At the top, along the midline of the tail, a horny keel stretches. The beaver's eyes are small; The ears are wide and short, barely protruding above the level of the fur. The ear openings and nostrils close under water, the eyes are closed by nictitating membranes. Molars usually do not have roots; weakly isolated roots are formed only in some old individuals. The incisors behind are isolated from the oral cavity by special outgrowths of the lips, which allows the beaver to gnaw under water. In the karyotype common beaver 48 chromosomes (the Canadian beaver has 40). The beaver has beautiful fur, which consists of coarse guard hairs and very thick silky underfur. The fur color ranges from light chestnut to dark brown, sometimes black. The tail and limbs are black. Shedding occurs once a year, at the end of spring, but continues almost until winter. In the anal area there are paired glands, wen and the beaver stream itself, which secretes a strong-smelling secretion - the beaver stream. The prevailing opinion about the use of wen as a lubricant for fur from getting wet is wrong. The secretion of the wen performs a communicative function, exclusively carrying information about the owner (gender, age). The smell of a beaver stream serves as a guide to other beavers about the border of the territory of a beaver settlement; it is unique, like fingerprints. The secretion of the wen, used in conjunction with the stream, allows you to keep the beaver tag in a “working” state longer due to its oily structure, which evaporates much longer than the secretion of the beaver stream.

Spreading

In early historical times, the common beaver was distributed throughout the forest-meadow zone of Europe and Asia, but due to intensive hunting, by the beginning of the 20th century, the beaver was practically exterminated in most of its range. The beaver's current range is largely the result of acclimatization and reintroduction efforts. In Europe, it lives in the Scandinavian countries, the lower reaches of the Rhone (France), the Elbe basin (Germany), the Vistula basin (Poland), in the forest and partly forest-steppe zones of the European part of Russia. In Russia, the beaver is also found in the Northern Trans-Urals. There are scattered habitats of the common beaver in the upper reaches of the Yenisei, Kuzbass, Baikal region, Khabarovsk Territory, and Kamchatka. In addition, it is found in Mongolia (Urungu and Bimen rivers) and in Northeast China (Xinjiang Uyghur autonomous region).

Lifestyle

In early historical times, beavers everywhere inhabited forest, taiga and forest-steppe zone Eurasia, along the floodplains of rivers reaching to the north to forest-tundra, and to the south to semi-deserts. Beavers prefer to settle along the banks of slow-flowing rivers, oxbow lakes, ponds and lakes, reservoirs, irrigation canals and quarries. Avoid wide and fast rivers, as well as reservoirs that freeze to the bottom in winter. For beavers, it is important to have trees and shrubs of soft deciduous trees along the banks of a reservoir, as well as an abundance of aquatic and coastal herbaceous vegetation that makes up their diet. Beavers are excellent swimmers and divers. Large lungs and liver provide them with such reserves of air and arterial blood that beavers can stay under water for 10-15 minutes, swimming up to 750 m during this time. On land, beavers are quite clumsy.

Beavers live alone or in families. Complete family consists of 5-8 individuals: married couple and young beavers - the offspring of last and current years. A family plot is sometimes occupied by the family for many generations. A small pond is occupied by one family or single beaver. On larger bodies of water, the length of the family plot along the shore ranges from 0.3 to 2.9 km. Beavers rarely move more than 200 m away from water. The length of the area depends on the amount of food. In areas rich in vegetation, areas may touch each other and even intersect. Beavers mark the boundaries of their territory with the secretion of their musk glands - a beaver stream. Marks are applied to special mounds of mud, silt and branches 30 cm high and up to 1 m wide. Beavers communicate with each other using odorous marks, poses, tail strikes on the water and whistle-like calls. When in danger, a swimming beaver slaps its tail loudly on the water and dives. The clap serves as an alarm signal to all beavers within earshot. Beavers are active at night and at dusk. In summer, they leave their homes at dusk and work until 4-6 am. In the fall, when the preparation of feed for the winter begins, the working day lengthens to 10-12 hours. In winter, activity decreases and shifts to daylight hours; At this time of year, beavers hardly appear on the surface. At temperatures below?20 °C, animals remain in their homes.

Huts and dams

Beavers live in burrows or huts. The entrance to a beaver's home is always located under water. Beavers dig burrows in steep banks; they are a complex labyrinth with 4-5 entrances. The walls and ceiling of the hole are carefully leveled and compacted. The living chamber inside the hole is located at a depth of no more than 1 m. The width of the living chamber is a little more than a meter, the height is 40-50 centimeters. The floor must be 20 centimeters above the water level. If the water in the river rises, the beaver also raises the floor, scraping soil from the ceiling. Sometimes the ceiling of the hole is destroyed and in its place a flooring of branches and brushwood is built, turning the hole into a transitional type of shelter - a semi-hut. In the spring, during high water, beavers build nests on the tops of bushes from branches and twigs with a bedding of dry grass. Huts are built in places where digging a hole is impossible - on low, swampy banks and in shallows. Beavers rarely begin building new housing before the end of August. The huts have the appearance of a cone-shaped pile of brushwood, held together by silt and earth, up to 1-3 m high and up to 10-12 m in diameter. The walls of the hut are carefully coated with silt and clay, so that it turns into a real fortress, impregnable to predators; air enters through the ceiling. Despite popular belief, beavers apply clay using their front paws, not their tail (the tail serves only as a rudder). Inside the hut there are manholes into the water and a platform rising above the water level. With the first frost, beavers additionally insulate their huts with a new layer of clay. In winter, the temperature in the huts remains above zero, the water in the holes does not freeze, and beavers have the opportunity to go out into the under-ice layer of the reservoir. In severe frosts there is steam above the huts, which is a sign of habitation. Sometimes in the same beaver settlement there are both huts and burrows. Beavers are very clean and never litter their homes with leftover food or excrement.

In reservoirs with changing water levels, as well as on small streams and rivers, beaver families build their famous dams (dams). This allows them to raise, maintain and regulate the water level in a reservoir. Dams are built below the beaver town from tree trunks, branches and brushwood, held together by clay, silt, pieces of driftwood and other materials that beavers bring in their teeth or front paws. If the reservoir has fast current and at the bottom there are stones, they are also used as building material. The weight of stones can reach 15-18 kg. For the construction of the dam, places where trees grow closer to the edge of the shore are selected. Construction begins with beavers vertically sticking branches and trunks into the bottom, strengthening the gaps with branches and reeds, filling the voids with silt, clay and stones. They often use a tree that has fallen into the river as a supporting frame, gradually covering it on all sides. building material. Sometimes branches in beaver dams take root, giving them additional strength. The usual length of the dam is 20-30 m, width at the base is 4-6 m, at the crest - 1-2 m; the height can reach 4.8 m, although usually 2 m. The old dam can easily support the weight of a person. The record in the construction of dams belongs, however, not to ordinary ones, but to Canadian beavers- a dam built by them on the river. Jefferson (Montana), reached a length of 700 m. The shape of the dam depends on the speed of the current - where it is slow, the dam is almost straight; on fast rivers it is curved towards the flow. If the current is very strong, beavers build small additional dams further up the river. The dam is often provided with a drain to prevent it from being breached by floods. On average, it takes a beaver family about a week to build a 10 m dam. Beavers carefully monitor the safety of the dam and patch it if it leaks. Sometimes several families working in shifts participate in the construction.

Swedish ethologist Wilson (1971) and French zoologist Richard (1967, 1980) made major contributions to the study of beaver behavior during dam construction. It turned out that the main stimulus for construction is the sound of flowing water. Possessing excellent hearing, beavers accurately determined where the sound had changed, which meant changes had occurred in the structure of the dam. At the same time, they did not even pay attention to the lack of water - the beavers reacted in exactly the same way to the sound of water recorded on a tape recorder. Further experiments showed that sound, apparently, is not the only stimulus. Thus, beavers clogged a pipe laid through a dam with silt and branches, even if it ran along the bottom and was “inaudible.” At the same time, it remains not entirely clear how beavers distribute responsibilities among themselves when teamwork. To build and prepare food, beavers cut down trees, gnawing them at the base, gnawing off branches, then dividing the trunk into parts. A beaver fells an aspen with a diameter of 5-7 cm in 5 minutes; a tree with a diameter of 40 cm is felled and cut up overnight, so that by morning only a sanded stump and a pile of shavings remains at the place where the animal works. The trunk of a tree gnawed by a beaver becomes characteristic shape « hourglass" A beaver gnaws, rising on its hind legs and leaning on its tail. Its jaws act like a saw: to fell a tree, the beaver rests its upper incisors against its bark and begins to quickly move its lower jaw from side to side, making 5-6 movements per second. The beaver's incisors are self-sharpening: only the front side is covered with enamel, the back side consists of less hard dentin. When a beaver chews on something, the dentin wears down faster than the enamel, so the leading edge of the tooth remains sharp all the time. Beavers eat some of the branches of a fallen tree on the spot, while others are demolished and towed or floated across the water to their home or to the site of dam construction. Every year, walking the same routes for food and building materials, they trample paths on the shore that are gradually filled with water - beaver canals. They float wood food along them. The length of the channel reaches hundreds of meters with a width of 40-50 cm and a depth of up to 1 m. Beavers always keep the channels clean.

Nutrition

Beavers are strictly herbivorous. They feed on the bark and shoots of trees, preferring aspen, willow, poplar and birch, as well as various herbaceous plants (water lily, egg capsule, iris, cattail, reed, etc., up to 300 items). The abundance of softwood trees is necessary condition their habitat. Hazel, linden, elm, bird cherry and some other trees are of secondary importance in their diet. Alder and oak are not eaten, but are used for buildings. The daily amount of food accounts for up to 20% of a beaver's weight. Large teeth and a powerful bite allow beavers to easily cope with solid plant food. Cellulose-rich foods are digested with the participation of intestinal microflora. Typically, the beaver consumes only a few tree species; To switch to a new diet, it requires an adaptation period, during which microorganisms adapt to the new diet. In summer, the proportion of herbaceous food in the beaver diet increases. In autumn, beavers prepare wood food for the winter. Beavers store their reserves in water, where they retain their nutritional qualities until February. The volume of reserves can be huge - up to 60-70 cubic meters per family. To prevent food from freezing into the ice, beavers usually heat it below the water level under steep overhanging banks. Thus, even after the pond freezes, food remains available to the beavers under the ice.

Reproduction

Beavers are monogamous and the female is dominant. Offspring are born once a year. The mating season lasts from mid-January to the end of February; Mating occurs in the water under the ice. Pregnancy lasts 105-107 days. Cubs (1-6 per litter) will be born in April - May. They are semi-sighted, well-furred, and weigh on average 0.45 kg. After 1-2 days they can already swim; the mother trains the beaver cubs by literally pushing them into the underwater corridor. At the age of 3-4 weeks, beaver cubs switch to feeding on leaves and soft stems of grass, but the mother continues to feed them with milk until 3 months. Grown-up young animals usually do not leave their parents for another 2 years. Only at 2 years old do young beavers reach sexual maturity and move out. In captivity, a beaver lives up to 35 years, in the wild 10-17 years.