Nutria – An Invasive Species

Coypu – The River Rat – Nutria

You may have seen them on the side of the road, on river banks, seemingly not hurting anything or anyone.  They are what looks to be a cross between a beaver and a rat.  The nutria are an herbivorous, semiaquatic animal.  The nutria was imported from South America for the fur trade in 1899 according to the U.S. Geological Survey.  Early accounts of the nutria accidentally being released into the wild was due to a hurricane that hit the Louisiana coast in the 1940’s. Also along that same line, the nutria were transported to Texas in 1941, spreading more into the wild due to yet another hurricane hitting the Mississippi River.

Nutria have been mistaken for beaver.  There are marked differences between the two, beavers sport a flat paddle like tail while the nutria tail is shaped like a rat’s round tail measuring 12 -18 inches long.  Weighing on average 12 pounds, being known to reach weights up to 25 pounds and typically two feet long.  The most distinct feature on the nutria is it’s front teeth.  They are a bright orange color and are very large.  If cornered, nutria can become very aggressive and caution must be used.

The nutria reach sexual maturity at 3 months for the female and 4 months for the male.  Why is this important to know?  Their gestation period is approximately 130 days.  The female can become pregnant the day after giving birth, with a litter of 1 to 13 baby nutria.  The babies are born fully developed and can eat alongside their parents within hours of their birth.  They are very aggressive reproducers.  If timed right, a single female can bear three litters per year.

Breeding nutrias was popular back in the 1950′.  It was a way to make extra money.  A farmer was able to purchase a male and female pair for $950.00 or three for $1600.00.  While some Oregon nutria farmers raised them for breeding purposes to be resold, others raised them for their pelts.  Once the market became over saturated with farmers, which took about 5 years, the nutrias were either killed and their fur sold or were simply let out into the wild.

Trapping dropped off in the 90’s due to low fur prices, allowing the nutria to reproduce at an alarming rate.

A destructive force

IMG_8849Once used for profit, nutria are now considered a destructive force, compounding with each birth.  They live alongside water ways, which include wetlands, dikes, and dams; digging burrows in which to live, the tunnels oftentimes reaching 20 feet long and measuring one to two feet wide, sometimes meeting up with other tunnels, weakening the soil that surrounds and support these important structures that we depend on, causing erosion and collapse.

The nutria destroy the area’s which they live, feeding on the lower stems of river plants “wasting” nearly 90% of the plant, which in turn disturbs the ecological balance of other animals and insects that live in that same habitat, and are known for digging through the banks to reach roots causing more erosion.  Once the plants are gone, known as an “eat out” they move on to yet another waterway.

They are known to eat and rob vegetable gardens; lettuce, cabbage, carrots, sweet potatoes to name a few, roots of trees, they dig up lawns feeding on the tender roots of sod.

There have been safety concerns with the EWEB canal, destabilizing the bank, which EWEB has addressed.  There has been damage to delta ponds restoration, nutria have caused serious plant damage. They are a nuisance to apartments on water ways, feces in their yard.  There are potential pet problems, a dog for example may be bitten, or sometimes, as dogs do, they could ingest the feces and become sick.

Control Methods

Nutria_Trapping_003According to the ODFW website: “In Oregon, nutria are classified as unprotected Non game Wildlife (OAR 635-044-0132).  As unprotected wildlife nutria may be trapped (cannot be relocated) or shot.  No license is needed for a landowner to control nutria on his/her own property.  Most cities have a restriction on leg-hold trapping or the discharge of firearms within their city limits – live trapping is usually the main population control measure inside the city limits.”

There are many “control method’s” out there, most not cost effective nor favorable to the environment.  One being Zinc Phosphide.  It is highly expensive and is toxic for up to many months, having to be reapplied after heavy rains.  The affects on other wildlife is not fully recognized, however birds and rabbits have been known to die from it.  Environmentalists would prefer baits of birth control, but this too is extremely expensive, costing roughly $6 million dollars annually.

Environmental damage due to the nutria was so severe in Louisiana, wildlife officials established a bounty per nutria in 2002.  Their project summary for the 2011-2012 Nutria Control Program:  354,354 tails worth $1,771,770 in incentive payments were collected from 285 active participants.

In Oregon, Polk County Soil and Water Conservation District began it’s own bounty program in 2010, establishing a capture or exterminate incentive. As of this printing, EDN has not heard back from PSWCD regarding the success of the program.

In an interview, Dan Godfrey, a trapper with the U.S. Department of Agriculture and Wildlife Services, had reportedly trapped in 2009 10 nutria, a year later on the same property he trapped thirty and the year following that close to 40 on a single property near the Coquille River.

Approximately 20,000 Nutria washed ashore on the beaches of Mississippi after hurricane Isaac in September of 2012.  It wasn’t a pleasant sight nor a problem easily solved, but a welcome one when you got down to it.

Louisiana has lost, to the nutria, wetlands equivalent to the size of the state of Delaware
Louisiana has lost, to the nutria, wetlands equivalent to the size of the state of Delaware

The nutria problem is a serious one.  The affects are multiplying constantly.  Louisiana has lost wetlands to the nutria totaling the size of Delaware.  Unlike Louisiana, nutria have more of an environmental impact in Lane County.

Brian Wolfer, Wildlife Biologist with the ODFW states there is no eradication program in Lane County.  It seems as though there are specific laws, somewhat complicated in order to get rid of the nutria.  They can not be captured and relocated, once caught, they must be euthanized in a humane way.

“some citizens feel it is not the nutria’s fault for being here, and feel they should let them go somewhere out of the location from where they were trapped”.  This only amplifies the problem really.  “they can bolster the populations… degrading the habitats in the area you take them to” Wolfer states.

“A landowner or their agent can trap or shoot them without a license to prevent damage and a license is not required.”  However, a license is required to hunt or trap them on public lands or on private lands if a person is not acting as an agent of the landowner. Discharge of firearms is prohibited in city limits, which includes air guns and archery.

A city resident would need a permit from ODFW to transport live nutria out of city limit to euthanize them in a humane way, as well as transport them to a location where it is legal to discharge a firearm.

According to Wolfer  “there are private businesses, referred to as Wildlife Control Officers, which landowners can hire to address damage or nuisance from furbearer’s and unprotected mammals.  A licensed Wildlife Control Officer can legally transport nutria for the purpose of euthanizing.  They are also required to follow humane standards when euthanizing wildlife.”

I asked Wolfer if there were plans for a control method in the future; “It comes down to money… who can afford the eradication of them, it is not an easy fix, and would have to be looked at as a long term program, which with budgets and the economy, it just really isn’t feasible.


Nutria have been marketed to the public as a very lean, fibrous and protein rich meat, possibly even better than beef, chicken and turkey as it is low in fat and cholesterol.  Studys published in the Journal of Food and Science suggest it is the same texture and appearance of rabbit or dark turkey meat.  It has been determined that nutria is safe for human consumption, but the idea hasn’t quite caught on here in Oregon.  Recipes can be found online.

Before trapping nutria, please ensure you are within your rights and responsibilities.  To learn more please contact the ORFW at

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