A long-whiskered, buck-toothed rodent called a nutria has come back to Tuolumne County for the first time in nearly 50 years, a situation troubling to local, state and federal wildlife authorities.
Nutria are on the state’s invasive species list, even though humans brought the beaver-sized rodents to California in 1899 for its fur.
Nutria ranchers and others eventually learned that nutria, released or escaped into the wild, were hyper-fertile, destructive herbivores with big appetites, capable of destroying the vital ditches, levees and dams that help convey and capture water, the state’s most valuable resource.
When the fur market shriveled up in the 1960s, the state imposed laws in 1970 forbidding raising nutria and set out to eradicate them. The state declared nutria eradicated in 1978.
But on Jan. 11, 2017, Peggy Sells, who takes wildlife photos and carries cameras with her on her journeys, spotted what she thought was a beaver.
Sells, a resident of Moccasin Ranch just outside the Hetch Hetchy company town of Moccasin, was out on Marshes Flat Road near Don Pedro Reservoir. She’d tried to take photos of beaver before, and she’d noted how human-shy and camera-shy they usually were.
“I’d never heard of a nutria,” she said. “I thought it was either a beaver or a muskrat. When I went to take pictures it didn’t run away. I even changed lenses and it didn’t move.”
Sells may have taken the first photo of a live nutria in California in decades, but she didn’t realize it until she saw a television news report about nutria just last week. When she saw images of the creature in the news report, she realized what she’d photographed 13 months ago.
“It looked exactly like the animal I saw a year ago,” Sells said. “It wasn’t a beaver.”
The television news report was likely based on a Feb. 8 news release from the California Department of Fish and Wildlife about nutria being discovered in the San Joaquin Valley.
According to Fish and Wildlife spokesperson Peter Tira, the first recent nutria was found in a trap just outside Gustine in Merced County in March 2017.
Since then, more than 20 nutria, including males, pregnant females and juveniles, have been documented at locations including private wetlands near Gustine, duck clubs, the Merced River near Cressey, adjacent to the San Joaquin River near Grayson, south of Dos Palos, the San Luis National Wildlife Refuge, and in Salt Slough on the San Joaquin River.
The full extent of the nutria infestation is not yet known, Fish and Wildlife staff said in their account distributed last week.
Now in four counties
Gary Stockel, agricultural commissioner for Tuolumne County, said Sells brought photos to his staff last Friday.
“They were taken in a cattle pond near the Mariposa County line, about a quarter mile from the reservoir.” Stockel said.
Stockel said they checked the photos and some staff thought it was probably a nutria. They forwarded the photos to a local trapper who works for the U.S. Fish and Wildlife Service and contracts with Tuolumne County, and to state Fish and Wildlife staff, and they confirmed the photos showed a nutria.
He said Nathan Graveline, with the California Department of Fish and Wildlife, and trapper Ron Anderson, searched for the animal on Monday, but didn’t find it and didn’t set traps.
Graveline said he and others have confirmed there was a nutria in Tuolumne County.
Stockel said county ag staff have reported it to state Fish and Wildlife, the lead agency on eradication efforts. There's a multi-agency meeting being scheduled to discuss response to multiple detections in four counties, Merced, Stanislaus, Fresno and now Tuolumne.
Scientists say nutria are native to South America and they’ve been introduced to Africa, Asia, Europe and North America, primarily by fur ranchers who raise them for their pelts. Its genus name, myocaster, derives from Greek words meaning beaver rat. In Spanish, the word nutria refers mainly to otter. Dutch and German names for the rodent also translate to beaver rat. In Italy it’s known as castorino, for little beaver. In Swedish, it’s swamp beaver.
Tira with state Fish and Wildlife says adult nutria can reach 3 feet in length, including the tail, and they can weigh up to 20 pounds. Nutria are “highly prolific” and they breed year-round. Average litters are 4 to 5 young and as many as 13 per litter, and they can have as many as three litters a year. Just 48 hours after giving birth, nutria are able to breed again. They reach sexual maturity at four to six months of age.
On Wednesday, Stockel shared some county ag records and state ag records that mention nutria and date to the 1960s and 1970. Their accounts match up with California Fish and Wildlife histories of nutria in the Golden State.
Nutria were introduced to the U.S. for their mink-like fur at Elizabeth Lake outside Lancaster in Los Angeles County in 1899, but they failed to reproduce. More nutria were imported, and records indicate nutria were present in the Central Valley and the southern coast of California in the 1940s and 1950s. The volatile fur market collapsed and raising nutria for pelts became less profitable.
A 1964 edition of the State of California Department of Agriculture Bulletin states “The number of nutria breeders obtaining state permits for the holding of this fur-bearing rodent continued to decline from the high of 324 in 1959.”
The same 1964 edition of Ag Bulletin also states “Feral nutria were reported in Wood Creek near Jacksonville in Tuolumne County and in the San Joaquin River area between Fresno and Madera counties, east of Highway 99. Both areas are under surveillance.”
At that time, there was a continuous detection program set up and maintained by the California Ag Department, the U.S. Bureau of Sport Fisheries and Wildlife, Branch of Predator and Rodent Control, and the county agricultural commissioner to locate and destroy feral nutria.
By 1970-71, there were just three nutria breeders registered in California. One was a lab in La Jolla, and two were raising nutria for their pelts in Fresno County. A state ag map shows that, as of November 1970, there were 300 nutria destroyed statewide and two-thirds of them were killed in Stanislaus and Merced counties, which border Tuolumne County. Four nutria were destroyed in Tuolumne County as of November 1970.
Where are they coming from now?
Stockel said Sells’ report was the first since 1970.
Asked where it came from, if it was a survivor of eradication efforts in the 1960s and 1970s, or if it’s a recent arrival, Stockel said there are three possibilities.
“One, there’s been a very small remnant population in the Don Pedro area and this is the first confirmed sighting since 1970,” Stockel said. “They would have been from feral nutria from when they were kept for the fur trade.”
Two, it’s a new introduction. It could have moved up from the Central Valley, also as a descendant from feral animals.
And three, it could have been someone who was keeping a nutria and they released it, Stockel said.
Since the 1970s it is illegal to keep nutria in captivity in California and it’s illegal to import them, Stockel said. It’s not OK to keep them as pets.
“They are very destructive to the landscape and they can burrow into levees and dams, which can cause them to collapse,” Stockel said. “They can create damage on stock ponds. At risk for example here in Tuolumne County is the TUD ditch system. And any other irrigation system for that matter.”
Graveline said he intends to put cameras out in the area where the Don Pedro nutria was spotted. Tira said the state Fish and Wildlife basic message is they are asking people to report any sightings or suspected sightings, and to share photographs and video with the state Invasive Species Program.
Contact Guy McCarthy at firstname.lastname@example.org or (209) 588-4585. Follow him on Twitter @GuyMcCarthy.