Scientific name: Myocastor coypu

What Is It?

Nutria is a medium sized rodent that lives in freshwater environments. It is native to South America. A nutria can grow up to 40 inches from its nose to the tip of its round, rate-like tail. It weighs an average of 12 pounds, although some may reach up to 40 pounds. It is an herbivore and feeds primarily on the roots and stems of wetland plants.

Is It Here Yet?

Yes. Nutria were introduced into Washington for the fur-farming industry in the 1930s. By 1943, there were feral populations. The nutria is a prolific breeder, capable of producing two litters a year. Populations are spreading rapidly throughout western Washington and are beginning to appear in central Washington.

Why Should I Care?

A nutria will consume about 25 percent of its body weight each day. Because it eats the roots and stems of plants, it destroys about ten times more plant matter than it eats. Nutria have been known to turn shoreline areas into muddy bogs, destroying marshes that provide protection for flooding and habitat for other animals. 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.

How Can We Stop It?

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 Its 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 1/2 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.

Additional Photographs