On the signs, especially on a structure of teeth, the muskrat has considerable similarity to voles. The sizes are large: body length on average about 30 cm, a tail — about 25 cm, weight is about 1 kg. Ears are small, hardly outstanding of wool. Legs are short, with big stupnyam. Between fingers of back extremities there are incomplete membranes. The tail is squeezed from sides and covered with small scales and rare hairs. Indumentum is formed by a long rough awn and a gentle dense underfur. Coloring of top from red to dark-brown, almost black copies sometimes meet.
The molt occurs, povidimy, once a year — in the summer. The small animal has the best skin from December to March. The homeland of a muskrat is North America where this animal is widespread almost throughout the United States and Canada. At the beginning of the XX century the muskrat was delivered to Europe where she quickly acclimatized and in some states began to get divorced from the trade purpose, for example in Finland.
Since 1927 delivery in the USSR of a muskrat from Western Europe and America began; in total over 250 copies were imported. At first they were let out on islands (Karaginsky, Solovki), and then and on the continent, in its northern parts. In process of growth of number began to make catching and transfer of already acclimatized muskrat. In total from 1928 to 1947 in 72 areas, edges and the republics more than 80 thousand small animals, and not only in the north of the country, but also in the south, to the Lake Balkhash inclusive where the muskrat perfectly was naturalized, bred were let out and it was widely settled. In Russia the area of a muskrat goes from borders of Finland through all forest zone of the European part of Russia and considerable part of forest-steppe and taiga zones of Siberia to the Far East and Kamchatka.
The muskrat leads a semi-water life, perfectly floats and dives. The aged man, small rivers and other reservoirs with plentiful coastal vodnobolotny vegetation lodges on coast of lakes. In more abrupt coast digs holes with underwater exits, and on low arranges "hatka" in the form of heaps of water and marsh plants and too with the underwater course. To an entrance to a hole the narrow trench which is formed from the continuous movement of small animals on one direction sometimes conducts. Holes of a muskrat are divided into simpler — fodder and long difficult — inhabited.
Eats various coastal and water plants: a sedge, strelolisty, rogozy, a water-lily, reed, an ezhegolovnik and so forth, eats also animal food, in particular mollusks.
Reproduction happens 1 — 2 time in the north a year, and in the south of 3 — 4. Pregnancy lasts 25 — 26 days. In each dung 6 — 7 cubs are born. There are they not only blind, but also almost naked. Grow so quickly that in a week they cut cutters and molars, and the body becomes covered by velvety gray fur. Eyes open for the 12th day, and at the beginning of the second month cubs become independent and settle near a hole of parents. In the southern areas young people of the first brood sometimes already begin to breed in the fall.
The muskrat is capable to far movements under the influence of a lack of a forage and places for housing. Especially intensive moving happens during a spring high water when it can migrate on tens and even on hundreds of kilometers.
The small animal is subject to various mass diseases, including a tulyaremiya, is exterminated by wild animals, birds and even large fishes and sometimes in a large number perishes from the hard frosts causing continuous frost penetration in reservoirs and a hatok and also from catastrophic droughts. As a result the number of this animal, as well as other rodents, is subject to sharp fluctuations.
In a number of places the digging activity the muskrat harms irrigating system, dams and dams. It causes damage to agriculture, especially rice growing; having uncontrolledly bred, destroys water and coastal vegetation. Not less than 10 prirodnoochagovy diseases, including a tulyaremiya and a paratyphoid are the natural carrier.
The muskrat is a numerous and widespread look as it is prolific and easily adapts to changes of habitat — construction of irrigation canals etc. However its number is subject to natural cyclic fluctuations — each 6 — 10 years it for the reasons which are not studied so far sharply falls.
Trade a muskrat by means of steel traps, and also wooden or from an iron grid of zhivolovny traps.