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Nutria - Fast Facts
Order - Rodentia
Family - Myocastor
This member of the rodent family is native to South America, and it was introduced both accidentally and purposely in the waterways in several American states. The species has proved to be overly destructive of habitat in some areas, creating problems for muskrats and waterfowl. This species can tolerate winters in temperate areas only. An important furbearer in Louisiana and Texas coastal area, nutria are viewed as detrimental in most other areas.
Adult nutria are about 24 inches long from the nose to the base of the tail. The tail itself is 12 to 17 inches long, round, and hairless. Coloration is brownish, and both sexes are similar in appearance and weight. The nutria is unique in that it has 3 sets or lengths of fur. Primary guard hairs are about 3 inches in length. Beneath this layer is the secondary guard hairs, which are more numerous and give the species its overall coloration. The underfur is short, and less dense than either a muskrat or beaver underfur.
The whiskers on a nutria are obvious. These whiskers are about 4 inches in length, and very numerous. Teeth number 20, and include 4 large incisors, and allows the nutria to cut off underwater plants without getting water into its mouth. The mouth also has glands located near the corners which produce oils that the nutria uses to comb and waterproof its fur. Nutria average 16 to 18 pounds in weight. Occasional individuals may weigh 25 pounds or more. Also unique is the location of the mammary glands on the females. The teats are locate high on the sides of the nutria, which allows young nutria to nurse as the mother swims in the water.
Front feet have five toes, including a small toe corresponding to our thumb. Hind feet are much larger, and unique in that all toes are connected by a skin web except for the toe corresponding to our little toe.
Nutria are apt to breed in any month of the year in North America. One male usually has 2 or 3 mates which share the same burrow. Female nutria mature at about 5 1/2 months of age, and female nutria usually have two litters per year. Many females breed within two days after giving birth to a litter.
Litter sizes vary according to a cycle. The first litter is small, with 2 to 4 being born. The second litter is larger with 4 to 6 offspring. The third litter is smaller than the second, and the fourth again increases in size. For one reason or another, each litter is either larger or smaller than the litter previous preceding it, and according to a pattern. If nutria litter sizes were averaged, five would probably be the average size. Female nutria are capable of producing only 6 litters as a rule. Females who produce seven litters in their lifetime are rare.
Nutria spend most of their time in or near the water. Although they are awkward and vulnerable on land the species will travel inland to feed upon preferred foods, including crops. Nutria are vegetarians and they do have large appetites. Primarily a surface feeder, nutria often overharvest favored foods, causing the production of less favored foods for themselves and other wildlife species. Nutria commonly cut off a preferred food near the waterline and swim or carry it to a feeding platform for eating. These platforms are used most often during the trapping seasons, possibly because they are warmer on the nutria's hairless feet. Favored foods for nutria include rushes, reeds, cattails, arrowhead, square-stem spike rush and sawgrass. Sugarcane, alfalfa, corn and rice are also eaten if available
Nutria are thought of as colonial because the same den is shared by the dominant male with two or three females and their offspring. Den entrances are often a foot or two beneath the water's surface, and the den entrance is often as much as two feet in diameter. The inner chamber of the den is above the waterline, and lined with grasses brought in to serve for bedding.
This species is territorial and tolerant of others of its kind. Four or five colonies of nutria to the mile of levees or dikes indicates a high population as a family or colony territory is about 1,000 feet in length.
Nutria do not remain underwater for long periods of time. Research shows that they are capable of holding their breath while submerged for about five minutes.
A shy and retiring species, nutria are not usually seen unless there is a deliberate attempt to find them. Nutria burrow into banks of ponds and lakes, and these holes are usually larger and more destructive than muskrat burrows.
• Adult nutria are about 14 inches long with a 12-17-inch tail, and can weigh up to 25 pounds.
• They have 20 teeth and 4-inch-long whiskers.
• Female nutria have two litters of 4-6 offspring per year, but are only capable of producing 6 litters. They are capable of mating any month of the year.
• A nutria is considered old if it reaches four years of age.
Tracks and Scat
The largest concentrations of nutria are in the southern coastal areas. Populations also occur in the eastern and northwestern coastal areas as well.
Nutria usually have a negative impact on other wildlife species. Because they are colonial in habitat, nutria often overharvest edible plants within their small range, resulting in the killing of the desirable plant species. These "eat-outs" destroy productivity as often less desirable plants replace the more desirable ones. Large populations of nutria definitely have a negative impact on the ability of the habitat to support both muskrats and waterfowl.
Nutria are preyed upon by alligators, cottonmouth moccasins, hawks, owls and eagles. Juveniles are usually most vulnerable to predation. Parasites include flatworms, roundworms, fleas and lice. The seeds of beggarstick also plague nutria as the barbed seeds entangle in the fur and puncture the skin, resulting in infections.
The roundworms infesting nutria can cause health problems for man. The roundworm larvae is present in the water where nutria are found, and this larvae can penetrate human skin. Known as "nutria itch", severe inflammation can result, which requires medical attention.
The sale of nutria furs is an important source of income for many trappers in regions where nutria are numerous. Most pelts are harvested in Louisiana, and around 2 million pelts are harvested annually.
A nutria is considered as old at four years of age.