You think the rats at L.A. City Hall are bad? Officials have a $1.9-million plan to rid state marshlands of giant rodents

2019 photo provided by the California Department of Fish and Wildlife shows a nutria in Merced County, Calif.
2019 photo provided by the California Department of Fish and Wildlife shows a nutria in Merced County, Calif.
(Calif. Dept. of Fish and Wildlife)
Share via

For more than a year, giant rodent invaders with orange-hued teeth have munched through California’s marshland, threatening significant damage to the state’s wetlands and water infrastructure.

Nutria — large, web-footed mammals native to South America that resemble beavers — showed up in Merced County in 2017, alarming wildlife officials with their propensity to quickly reproduce, their voracious appetite for vegetation and their ability to destroy underground infrastructure.

The animals can grow to 2½ feet in length and weigh 20 pounds and are recognized by their extra-large reddish-orange incisors. And, boy, do they use them.


Nutria populations not only destroy the state’s already diminished wetlands by consuming vegetation, but also burrow into the ground, potentially damaging irrigation canals and levees. This poses a risk to the state’s drinking water supply and could expose communities and farm fields to flooding, said Peter Tira, a spokesman for the California Department of Fish and Wildlife.

Officials worry the semiaquatic rodents, which have been found on the fringe of the San Joaquin River Delta, will ravage the area and harm infrastructure that sends water to San Joaquin Valley farms and urban areas.

Wildlife officials have developed a plan to remove the nutria before their population explodes out of control but say they need more money to make that happen.

The California Department of Fish and Wildlife asked the state Legislature last month to appropriate $1.9 million for the 2019-20 fiscal year to pay for a dedicated team of 10 scientists, analysts and other experts to track and eradicate the pests. The agency also asked for $1.6 million in subsequent years to fund the program.

Officials have already started hunting down the critters but say their efforts have been crippled by a lack of full-time staff.

“Almost every female we’ve caught has been pregnant. They’re incredibly prolific, which is why we have to get on it quickly,” said Tira.


“They’re a threat to our multibillion-dollar agricultural economy, and they’re a public safety threat,” he added. “If they get entrenched in the Delta, they pose a huge threat to our water. It would be hard to get them out of there, and it would have consequences for the whole state.”

Senior Wildlife Biologist Greg Gerstenberg examines three nutria caught near Gustine, Calif., within the previous two days in February 2018.
(Randall Benton / AP)

State biologists had trapped 386 nutria in California as of last week. The majority of the creatures — 316 — were found in Merced. However, experts have captured the animals in San Joaquin, Stanislaus, Tuolumne, Mariposa and Fresno counties.

The nutria population is growing faster in the Central Valley than the state can currently combat, officials said, in large part because of their reproductive cycles. Females can produce up to 13 young per litter, have a relatively short gestation period and can breed again within 48 hours of giving birth.

“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,” the Department of Fish and Wildlife wrote in a proposal to the state Legislature. It is not clear when — or if — the Legislature will consider the proposal.

Nutria were first brought to California in the late 1800s in an effort to establish a fur farm industry. When that business collapsed in the 1940s, some of the animals were released into the wild. State records indicate that nutria were present in the Central Valley and the south coast of California. They were declared eradicated from the state by the 1970s — until one showed up in a beaver trap in spring 2017 in Merced County. Since then, the population has exploded.


Trapping nutria is a meticulous process that involves sending biologists to survey landscapes for scat or other signs of the rodents and setting up cameras to confirm their presence. If nutria are spotted, trappers nab the animals, which eventually are euthanized. When nutria show up on private property, state officials have to negotiate with property owners for access to corral them.

“We believe we’ve caught the infestation early enough that we can remove them from California, but it’s not going to be quick,” Tira said. “It’s going to take a few years, for sure.”

Twitter: @Hannahnfry