California

They’re big, furry and could destroy the Delta. California has a $2 million plan to kill them

Check out the giant rodents overtaking the San Joaquin River Valley

Nutria, a giant South American rodent, is an invasive species in California’s San Joaquin River Delta. The California Department of Fish and Wildlife has a plan to exterminate animals, but it will take more money and staff.
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Nutria, a giant South American rodent, is an invasive species in California’s San Joaquin River Delta. The California Department of Fish and Wildlife has a plan to exterminate animals, but it will take more money and staff.

California’s San Joaquin River Delta is in danger of being overrun by voracious beagle-sized rodents. The state has a plan to deal with them, but it’s going to take a lot of time and money.

Nutria, a large South American rodent, have become an invasive species in several states, including Louisiana, Maryland and Oregon. In March 2017, they were found in Merced County, alarming California wildlife officials because of the rodents’ potential to harm the water infrastructure that nourishes San Joaquin Valley farms and delivers water to thirsty cities.

Nutria can give birth to litters up to 12, and become pregnant again within 48 hours of doing so. They live in marshland and feed heavily on vegetation. Where they appear, ecological calamity follows, according to the state.

“Based on what is known about nutria and their current reproductive rate and distribution, without immediate action, nutria will rapidly expand their numbers and geographic presence and cause extensive damage to wetlands, riparian habitat, restoration projects, levees, water conveyance and flood-protection infrastructure, and agriculture,” according to a memo from the California Department of Fish and Wildlife.

Large invasive rodents may be invading California's Delta. A small team of Fish & Wildlife field biologists is assessing the danger nutria pose for wreaking havoc on the Delta.

That memo requests that the California Legislature appropriate $1.9 million for the 2019-20 fiscal year, and $1.6 million in funding in each subsequent year, to pay for a dedicated team of experts who track and eradicate the rodents.

Peter Tira, a Fish and Wildlife spokesman, said state biologists have trapped 386 nutria in California. Most of them were found in Merced, where biologist trapped 316 of the critters. They captured 56 in San Joaquin County, 12 in Stanislaus County and one each in Tuolumne and Fresno counties.

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California Department of Fish and Wildlife senior wildlife biologist Greg Gerstenberg holds a nutria caught near Gustine in February 2018. Randall Benton rbenton@sacbee.com

Within five years, the state estimates there could be nearly a quarter million nutria chewing up California’s endangered wetlands.

Right now, the Nutria Eradication Project has only one full-time, dedicated employee, an environmental scientist. The department is asking for funding for 10 full-time equivalent positions .

It’s not clear how the nutria, which have been a major environmental pest in California’s northern neighbor, Oregon, got into the state.

An infestation of nutria, an invasive swamp rodent, was recently found in the Sacramento-San Joaquin Delta. See how to identify them and report sightings.

“We don’t know. We may never know,” Tira said. “But regardless, they’re here and we have to deal with them and we are dealing with them.

He said the primary concern is keeping nutria out of the San Joaquin River Delta. Nutria burrows in irrigation canals and levees pose a risk to drinking water and could expose downstream communities and farm fields to flooding.

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A dispatched nutria’s right foot is shown, photographed Wednesday, June 13, 2018 near Newman. Nutria have webbed feet, except for the outer toe. Eric Paul Zamora ezamora@fresnobee.com

Trapping nutria is a painstaking process. First biologists go in and survey for signs of the rodents, and then they use trail cameras to confirm their presence. Often, nutria habitat, which is rugged and marshy, falls on private property, meaning state officials have to negotiate with the property owners for access.

“We’re optimistic we can remove them from the state, but it’s going to take some time, take some money,” Tira said. “It’s not going to happen overnight.

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Andrew Sheeler covers California’s unique political climate for McClatchy. He has covered crime and politics from Interior Alaska to North Dakota’s oil patch to the rugged coast of southern Oregon. He attended the University of Alaska Fairbanks.


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