California steps up efforts to fight invasive marsh rodents



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One of the most recent threats to the Californian environment is webbed feet, white whiskers, hard coat fur and orange cabbage teeth that could be confused with carrots.

"Damn it's a ugly thing," said David Passadori, almond and nut farmer in central California. "And how they multiply – I do."

Swamp rodents, called nutria, trigger alarms in California. They weigh about 20 pounds each and eat the equivalent of about a quarter of their weight each day by sinking into the banks of rivers and nibbling plants emerging from the water.

Animals can destroy wetland habitats of rare and endangered species, degrading soils, ruining crops and carrying pathogens that may threaten livestock.

Above all, they pose a risk to public safety: if they are not controlled, the nutria could jeopardize California's water supply, particularly if they enter the delta of the Sacramento-San Joaquin River. .

According to Peter Tira, spokesman for the state's Department of Fish and Wildlife, Delta is the "beating heart of California's water infrastructure." It contains a network of more than 1,000 km of canals and dikes that protect the region from floods, provide drinking water for millions of Californians and irrigate the lush agricultural region.

Now armed with $ 10 million in public funding, the Wildlife Protection Agency is deploying new tactics to eradicate nutria and attempt to prevent the massive destruction that they are supposed to cause .

"In the last two years, our best efforts have been to try not to control the population, but to prevent it from exploding, while seeking the resources to truly eradicate it," said Valerie Cook, who is responsible for Nutria Eradication Environmental Program, recently established by Fish and Wildlife. Program.

"We have not had nutria in California for 50 years, so nobody really knows about them," Tira said. "We had to learn to work as we went."

An invasive species native to South America and introduced to the United States at the height of the fur trade at the end of the nineteenth century, nutris would have been eradicated in that state in the 1970s, until that time. that they are discovered in a beaver trap in 2017. For more than 700 nutria have been trapped and killed, including four on the property of Passadori.

Farmers, landowners and biologists in the Central Valley have been on maximum alert.

A recent morning in Merced County, where the most nutrients were found, state biologists Greg Gerstenberg and Sean McCain kayaked in a cattail-covered wetland pond. Wearing waders, they dragged themselves in the deep water up to the chest to check for surveillance cameras and cage traps where they left pieces of sweet potatoes to attract invasive rodents.

Last year, wildlife officials removed nearly 90 nutries from this pond. Gerstenberg and McCain are back as they feel that at least some nutria are back. But this morning, they found only muskrats, smaller rodents living in the swamps, and released them into the pond.

"Our goal is to go get them here and eliminate them before they are fully implanted in our central valley," said Gerstenberg, veteran biologist of fish and wildlife.

The Central Valley is the most productive agricultural region of the United States. It produces more than half of the country's fruits, vegetables and nuts, including almost all of its apricots, table grapes, carrots, asparagus and nuts. Figures from the Federal Department of Agriculture have established that the market value of agriculture in the Central Valley Valley in 2017 rose to nearly $ 29 billion.

Damage to the region's soil or water infrastructure would be devastating for the economy and food.

Invasion of rodents in the swamp

Sean McCain, a scientist with the California Department of Fish and Wildlife, is installing a feeding platform to draw nutria in front of a surveillance camera in Stevinson, California.

(Associated Press)

"That would mean that there would be more sushi, because the alternative would be to buy rice from Japan or Korea, where the price is five times higher," he said. said Daniel Sumner, director of the Agricultural Issues Center at the University of California at Davis. "Embrace carrots, or live without table grapes in summer."

Surveillance cameras and landowners helped locate the elusive night-time creatures over an area of ​​nearly 13,300 square miles that wildlife officials are assessing for nutria habitats. Live traps baited with sweet potatoes donated by farmers help capture them. Once identified as nutria, the animals are slaughtered. Tira said that about three quarters of the female nutries were found pregnant – they can have up to three litters a year, which allows them to repopulate quickly.

New attention and funding will allow Fish and Wildlife to hire 46 dedicated people. In December, the agency will launch a program called Judas Nutria, which would equip nutria sterilized surgically with radio collars and send them to the wild. Because animals are very social, they will lead the team to other nutria.

Fish and Wildlife will begin genetic testing before the end of the year to determine where they come from. Tira said that migrations from Oregon or Washington were questionable, but the team is not sure whether the nutria were reintroduced to California or some of the remaining population.

Inspiring from the East Coast of Maryland and parts of Delaware and Virginia, officials will also test trained dogs to sniff out the scent and feces of rodents.

"We can not succeed if we can not find all the animals," said Cook.

In addition to threatening agriculture and infrastructure, nutria can harm wetlands, which play a critical role in preventing carbon dioxide from entering the atmosphere and helping to mitigate global warming.

The Central Valley is also home to the largest concentration of migratory waterfowl on Earth, said Ric Ortega, general manager of the Grassland Water District.

"In California, we have very little surface water in reserve," he said. "It's not a wetland if it's not wet. Nutria complicates that.

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