The Statesman Journal in Salem, Oregon recently published an article on one of the most problematic invasive species in the National Wildlife Refuge System — the non-native nutria.

Nutria are South American aquatic mammals that were originally introduced into North America for the fur-farming industry. When it became clear the market for their fur was not viable, many nutria were set free (while some escaped) and proceeded to take over the local habitat, pushing out native muskrat and river otters, eating up large swaths of plants, and destroying wetlands. Nutria are now found in fresh and salt water ponds and swamps in the mid-Atlantic, Southeast, Great Lakes, and Northwest states.

Two of the most destructive habits of nutria is that they like to tunnel and they like to eat the root balls of marsh plants. At places like Blackwater National Wildlife Refuge in Maryland, nutria caused such devastation that large areas of the marsh were reduced to mud banks, devoid of plant material. Eventually some wetland areas eroded so badly that they were overtaken by the local waters. A consortium of government agencies and nonprofit groups worked together to rid the refuge of the nutria — for now. But the rodents still inhabit parts of Maryland’s Eastern Shore, which surrounds the refuge, and according to officials it will take about $1 million a year to keep Blackwater safe from another invasion. But at least now the refuge staff can begin rehabilitating those wetland areas that were not lost to open water.

As bad as Blackwater Refuge’s problems have been, Louisiana is without a doubt the one state with the most storied history in battling the invasive nutria, and reports estimate that approximately 34,000 acres of Louisiana’s coastal wetlands are impacted by nutria at this time.

Louisiana officials have tried to develop creative ways of ridding the state of the mammal, and harvesting nutria for pelts and meat (mostly for foreign markets) has had some success, with approximately 95% of the nutria harvest in the United States now occuring in Louisiana. But Louisiana officials have set an ambitious goal of harvesting up to 400,000 nutria along coastal Louisiana every year, and the battle to do so will be daunting.

As for Oregon and Washington state, their nutria problems are not quite as severe but are clearly growing, and the invasive rodents are causing problems at places like Ridgefield National Wildlife Refuge along the Columbia River. According to the Statesman Journal:

…chewing and digging nutria are causing roads to collapse, earthen dikes to erode and water to flow where it shouldn’t.

“The burrow entrances are underwater, so a lot of times you don’t know (a burrow) is there until it is too late, until the road starts to crack and crumble. You can dump stuff in there, but that won’t stop them,” said Joe Engler, refuge wildlife biologist. “In some cases, we’ve tried to put fencing along the slopes of sides to try to keep them at bay, but we have dozens and dozens of miles of dikes, so to think of putting fencing on all of them is just too expensive.”

The nutria also chew away the wooden boards refuge staff use to contain water in certain wetlands.

Unfortunately some locals have taken to feeding the nutria — a highly inadvisable activity when so many authorities are trying to rid the local ecosystems of the destructive animal:

“We have problems with people feeding them, and we highly discourage that,” said Jim Gores of the Oregon Department of Fish and Wildlife. “They are not just cute furry critters. They have some incisors on them that can lop off a finger if you are not careful.” Officials also warn that nutria carry diseases, although not much is known about the illnesses they can spread to people, livestock or pets.

Fortunately help might be on the way in the form of a national nutria management plan:

Trevor Sheffels, a graduate student in environmental management at Portland State University, is taking the lead in addressing Oregon’s nutria problems.

He is on the Aquatic Nuisance Species Task Force, which is trying to devise a national nutria management plan — with regional recommendations for dealing with the rodents.

“Right now it has been on the local landowners level as far as management with no coordinated efforts,” Sheffels said. “Nutria breed so quickly — so if there is not a coordinated effort, they can’t be (dealt with appropriately.)”

For more information on nutria, and efforts to rid refuges of this rodent, visit the Blackwater NWR Nutria page. Also, check out the Nutria section at the National Invasive Species Information Center website. And visit Nutria.com, which is run by the Louisiana Department of Wildlife and Fisheries, for an overview of the state’s ongoing battle with nutria.

wildlife, wildlife refuge, conservation, nutria, invasive species