INVASIVE SPECIES WATCHLIST | NUTRIA

Nutria, is it a rat, a beaver or an unwanted pest?  Most people think of them as a combination of all three, I like to think of them as a large rat or beaver with a small tail.  Nutria, or as a wide portion of the world calls them Coypu have been around since the age of man and has a fairly long history.

Nutria is native to South America, and was first introduced in the U.S. in 1899 in California as fur.  Between 1899 and 1940 they were imported for fur use not only in California but Washington, Oregon, Michigan, New Mexico, Louisiana, Ohio, and Utah.  “Nutria” actually stands for the fur of the Coypu, which helps explain the name confusion.

When the Nutria Fur trade collapsed in the early 1940’s business owners and trappers simply let the animals go free, and many of the species were relocated across the nation as a control for vegetation by state and federal agencies.  In the free market of America, where capitalism is quick to make a few bucks, these critters were sold to the public as “weed cutters.”

Nutria have short legs and highly arched bodies, measuring roughly two feet in length.  They have a rounded tail that is a little over a foot long with little hair.  They weigh approximately 12 pounds but can range anywhere from 20 to 40 pounds, and have a dense grayish undercoat that is covered by glossy guard hairs that range from dark brown to a yellowish/tan color, as well as white whiskers on each side of their nose.  Nutria have large incisors that are yellow/orange to an orange/red on the outer surfaces, and are commonly mistaken as the American beaver or muskrat.

Highly developed and adapted for aquatic life, Nutria inhabit farm ponds, drainage canals, bayous, freshwater and brackish marshes, swamps, and rivers.  Feeding on bulrushes, cordgrass, roots, and rhizomes and tubers from cattails.  These rodents have caused local concern, due to the fact that they make great hosts for several pathogens and parasites that can infect people, pets and livestock.  Their eating, digging, and rooting habits cause erosion and convert healthy marshes into open water habitat, ruining several native species homes, destroying wetlands and potential hunting sites.  Another concern is lack of predators that eat Nutria, especially since it has a high reproductive rate.

Though our harsh winters make it hard for Nutria to survive in Michigan, if you do encounter one, you can report it to www.michigan.gov/invasivespecies for contact information, or you can also report it using the MISIN smartphone app or through their website www.misin.msu.edu.  Early detection is our best response for dealing with this species, and reporting these occurrences in a timely manner is crucial for stopping an invasion and limiting the negative ecological and economical impacts.

This article is part of the ongoing series on invasive species funded in part with funds from the Michigan Invasive Species Grant Program through the Department of Natural Resources, Environmental Quality, and Agriculture and Rural Development. 

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