Nutria Rat: Bethany Riegel

Also known as… Scientific name: Myocastor coypus Molina Common names: Nutria, coypu, coypu rat, nutria rat, swamp beaver

Introduction The Nutria Rat was native to South America, and was introduced to North America in the 1930’s.

Most likely to be found in… They are most likely to be found near areas with large amounts of water like lakes, streams, ponds, marshes, bayous and swamps. http://www.geocities.com/Heartland/Farm/7720/nutria.html

Description When full grown, nutrias are about 2 feet in length excluding the tail. The average adult weight is 18 to 25 pounds. They are semi-aquatic rodents with webbed hind feet and appear to be equally at home in fresh or salt water, warm or cold. http://www.geocities.com/Heartland/Farm/7720/nutria.html

SMILE! Nutria rats have 2 upper and 2 lower incisors which are razor sharp. They use these to gnaw on plants. http://www.geocities.com/Heartland/Farm/7720/nutria.html

Main food source Nutria are almost entirely herbivorous and eat animal material (mostly insects) incidentally, when they feed on plants. Freshwater mussels and crustaceans are occasionally eaten in some parts of their range. Nutria are opportunistic feeders and eat approximately 25% of their body weight daily. They prefer several small meals to one large meal. http://www.extension.org/faq/973

Food source continued… Their natural food consists almost entirely of aquatic and semi aquatic vegetation, but when these animals live along the coast they also feed upon shellfish. Cattails, reeds, and sedges appear to be especially prized items of food. When established near gardens, they take cabbage readily; they are also fond of carrots and sweet potatoes. http://www.nsrl.ttu.edu/tmot1/myoccoyp.htm

Reproduction: A female nutria averages about five young per litter, but can birth as many as 13 at a time. A female can breed again within two days after giving birth, meaning one nutria can have up to three litters per year. http://www.sciencedaily.com/releases/2008/03/080306094624.htm

Reproduction continued… The gestation period is from 127 to 132 days. At birth the young are fully furred, and their eyes are open; they are able to move about and feed upon green vegetation within a few hours. At that time they weigh approximately 200 g. They mature rapidly, increasing at the rate of about 400 g per month during the first year, and reach sexual maturity at the age of 4 or 5 months. Females sometimes give birth to their first litter when they themselves are 8 or 9 months old. http://www.nsrl.ttu.edu/tmot1/myoccoyp.htm

Predator vs. Prey There are only two predators for the nutria rat Alligators Humans Preys of the nutria rat consist of: Snakes turtles Gar some raptors http://www.geocities.com/Heartland/Farm/7720/nutria.html

Relatives Beavers are relative to the nutria rat, and in which sometimes the nutria rat is mistaken for a beaver because of their similar characteristics.

Differences The tail of the nutria is round and nearly hairless like the tail of the common lab rat while the beaver's tail is flat; nutrias have a far better disposition than beavers do both in the wild and in captivity. http://www.geocities.com/Heartland/Farm/7720/nutria.html

Competition with muskrats Because of their known competition with muskrats, which are well-established and valuable fur-producing animals in this country, it appears that muskrats may be driven out and replaced by the much less desirable nutria

Interesting facts An interesting fact about nutrias is that the mammary glands of the female are located high on the back, NOT on the belly. This facilitates feeding the young in their aquatic environment. Because nutrias reproduce so quickly (one female can produce up to 150 young in 16 months and they appear to breed year round), they quickly exhaust the food supply in their areas and have to move on. http://www.geocities.com/Heartland/Farm/7720/nutria.html

More facts They are almost entirely nocturnal, consequently their presence in an area usually is revealed only by their trails, feces, and lengths of cut vegetation that have been left in their trails. http://www.nsrl.ttu.edu/tmot1/myoccoyp.htm

Problems The feeding habits of the nutria cause millions of dollars of damage yearly. Both rice and cane farmers experience problems with this nomadic rodent and even home gardeners will find that cabbage, carrots and sweet potatoes may attract these hungry herbivores. http://www.nsrl.ttu.edu/tmot1/myoccoyp.htm

More problems… They do reduce many kinds of aquatic plants, but they will not eat "moss" (algae) and many of the submerged plants. At times they do the job too well. The trouble is that once nutrias get established in a lake, their high reproductive capacity soon results in overpopulation. There are so many nutrias that the available food supply will not satisfy them, and then trouble begins. The animals move into places where they are not wanted or where they destroy vegetation that is valuable for such wildlife as waterfowl and muskrats http://www.nsrl.ttu.edu/tmot1/myoccoyp.htm

Life span… The maximum length of life for nutria kept in captivity is 12 years, but the life span in the wild probably is considerably less.

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