What are they?
Nutria are medium sized rodents that live in freshwater environments. They are native to South America. Nutria can grow up to 40 inches from its nose to the tip of its round, rat-like tail. They weigh an average of 12 pounds, although some can reach up to 40 pounds. They are herbivores and feed primarily on the roots and stems of wetland plants.
Are they here yet?
Yes. Nutria were introduced into Washington for the fur-farming industry in the 1930s. By 1943, there were feral populations. Nutria are prolific breeders, capable of producing two litters a year. Populations are spreading rapidly throughout western Washington and are beginning now to appear in central Washington.
Why should I care?
Nutria will consume about 25 percent of their body weight each day. Because they eat the roots and stems of plants, they destroy about ten times more plant matter than they eat. Nutria have been known to turn riparian areas into muddy bogs, destroying marshes that provide protection for flooding and habit for other animals, birds, and fish. Nutria often construct circular platforms of compacted vegetation, which they use for feeding, birthing, resting, and grooming. Nutria are known to construct burrows in levees, dikes, and embankments, causing bank collapse and erosion. They also are host to a variety of parasites and pathogens.
What should I do if I find one?
Call 1-877-9-INFEST or report online.
How can we stop them?
At this time the Washington Department of Fish and Wildlife recommends that property owners contact a state-licensed trapper to capture and remove the animals. Any live-trapped nutria must be euthanized and not returned to the wild or transported within the state.
What are their characteristics?
- Male and female nutria are very similar in appearance.
- The average adult is about 2 feet long from nose to the base of the tail.
- The rat-like, sparsely haired tail is 1-1.5 feet long.
- The fur of a nutria has three lengths. The short under fur is less dense than that of either a muskrat or beaver. The next layer is longer, more dense, and is the primary overall coloration of the species. The outer layer hairs are about 3 inches long.
- Nutria’s whiskers are about 4 inches long.
- The front feet have five toes, one of which is a small toe akin to the human thumb. The hind feet are much larger and all the toes, except the one corresponding to the little toe in humans, are connected by a skin web for swimming.
- The nutria has glands near the corners of the mouth that produce oils the nutria uses to groom itself and waterproof its fur.
- The mammary glands on females are high on their sides, which allows their young to nurse while the mother is swimming.
- Nutria spend much of their time in water.
Where can I get more information?
- Washington Department of Fish and Wildlife
- Washington State Puget Sound Partnership
- U.S. Department of Agriculture’s National Agricultural Library