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Nutria are hungry pests

Nutria have voracious appetites.

This report is part of an occasional series that examines some of the more entertaining and outlandish aspects of local history.

The beaver is an animal that, collectively, the Pacific Northwest is pretty fond of. But before Oregon was naming college sports teams after beavers, it was their fur that people loved. Beaver pelts were one of the region’s first major exports, with their water-repellent furs working as a basic unit of trade in the frontier regions. Eventually, fur was replaced as the region’s economic keystone, but local fur producers tried to reinvent themselves with a new animal: nutria.

Originally from Argentina, nutria are a distant cousin to local rodents, including the beaver and muskrat. At a distance, they might be mistaken for local animals, except for two distinguishing features. Their tails are neither the broad, flat tail of the beaver or the narrow, hairless muskrat tail. Instead, their tails are round, thin and hairy. But their most eye-catching feature are their front teeth, which are an almost fluorescent shade of orange. And unlike beavers or muskrats, nutria are considered an invasive pest.

According to the Washington Department of Fish and Wildlife, the first nutria were brought to the region in the 1930s. Nutria were pitched to fur farmers as a new animal that would not only provide pelts, but also control weeds. A nutria’s appetite, approximately 25 percent of their body weight a day in plants, was presented not as a problem, but a benefit.

By the 1940s, feral nutria populations had established themselves along the Columbia, Cowlitz and Chehalis rivers. Some animals simply escaped, while others were released when their pelts proved to be less lucrative than the animal importers had promised. Others were released due to accidental property destruction, such as when, according to The Chronicle, a Chehalis building housing a “nutria co-op” was gutted by a major fire.

Accidents and low profits largely torpedoed efforts by groups like Purebred Nutria Associates, Inc. to establish lasting nutria farms here. Released and escaped animals quickly established themselves and started breeding like all rodents — rapidly.

Once enough nutria had escaped, their adverse effects on the environment became apparent. They had few natural predators and, coupled with their females’ ability to have up to 40 young, their numbers can quickly become overwhelming. Nutria swiftly began displacing local populations of beavers and muskrats.

Their diet of roots and tubers also means that they destroy roughly 10 times as much plant matter as they consume. This reduces the natural flood protections in riverside areas, as they leave behind only mud.

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Nutria also burrow, making them a particular problem for human efforts to control flooding as well. Levees and dikes make particularly attractive locations for nutria to burrow into, and extensive infestation can lead to erosion or even total collapse.

Local, state and federal agencies have all tried to control nutria populations. According to a 2012 TDN article, during the mid-90s, the Longview diking district was budgeting $60,000 a year on trapping them. The State of Washington paid $5,000 for a two-man team to trap as many nutria as possible around Lake Washington in the face of a serious infestation. The U.S. Department of Agriculture also dispatches trapper teams to help control population explosions across the country, as was the case with the 2011 infestation of Lake Washington.

These efforts have curtailed the population growth, with trapper hauls decreasing 90 percent from 2005 to 2012. But nutria are highly mobile animals and removing them from an ecosystem once they have established themselves is almost impossible, so they still crop up in ditches, embankments and riverbeds around Cowlitz County.

While shooting nutria is perfectly legal, the WDFW website reminds everyone that it is illegal to discharge a firearm within city limits. If you see the animals within a city, they ask that you report your sightings online. A licensed trapper will be dispatched to the area to remove and euthanize the animals.

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