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Cedar Mill News

Volume 2, Issue 2


February 2004

The Nutria that ate my yard!

By Kyle Spinks, THPRD Natural Resources Technician

With so many streams, small ponds, and wetlands in Cedar Mill, it’s not surprising that our water-loving wildlife neighbors do so well. One of the most successful of these is the nutria, an exotic rodent from South America. Adults weigh in at 15-20 pounds and look like a very large rat, with brown fur, a hairless tail, and large, orange front teeth. Nutria have a light patch of fur directly in front of the ears, distinguishing them from beavers, which are all brown and usually larger.

Nutria are typically nocturnal. They share habitat with muskrats and beaver, both of which are nocturnal, so they may adjust their behavior to a daytime regimen to fit in the niche better and avoid conflicts and competition for resources.

Nutria were introduced back in the 1930s and actively promoted by entrepreneurs to fur farming operations through the 1950s and 60s. Many animals escaped or were released and successfully colonized the Willamette Valley, taking advantage of the surplus of food and the mild winters. Farmers soon recognized these animals as a nuisance: crops were eaten by these voracious vegetarians, and the banks of irrigation canals and ponds began collapsing as the extensive tunnel systems became saturated.

These problems have continued through the present day, but have moved into suburbia as well. People who live next to wetlands see their lawns and garden plants eaten and the streambanks next to their yards becoming honeycombed. Wetland restoration sites are impacted too, and Clean Water Services estimates $1-2 extra cost per plant to protect their native plantings in Washington County.

If you find them in your yard, try scaring them away with loud noises, but don’t try to touch or pick them up and make sure to keep small pets clear of them. Nutria can be quite aggressive and there are reports of people and animals being bitten or scratched, especially when a mother is protecting her young.

To protect your garden, try screening individual plants and/or adding a low fence across the yard to keep the nutria out. The use of dogs to scare them off has proven effective but this method is legal only on private property, otherwise it’s considered wildlife harassment and a dog owner could get in trouble. Trapping is sometimes used to handle the problem, but new animals typically move into the site soon afterwards. The best method of reducing the problems is by making the habitat uninviting…a gentle ‘suggestion’ to them that your yard isn ’t the best place to live.

Nutria will eat most herbal vegetation that’s near water, including lawns, rushes, and the tender new shoots of some shrubs. They will also chew off a woody shrub branch to reach the tender shoots. They won’t chew down a tree, like a beaver will, so if you see such evidence, you’ve got beavers, not nutria, in the area.



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The Cedar Mill News
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Publisher/Editor:Virginia Bruce
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