'Rodents of Unusual Size' not a Princess Bride fantasy: Nutria out of control in California

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"Rodents of unusual size? I don't think they exist."

Well Wesley, indeed they do.

It's as if the writers of the movie "The Princess Bride" knew that Rodents of Unusual Size would one day threaten California, gobbling up so much aquatic vegetation that they would be threatening wetlands and marshes.

Last week, the California Department of Fish and Wildlife said wardens had found more than 20 "nutria" in wetlands, rivers and canals and in Merced, Fresno and Stanislaus counties.

Wardens were trying to figure out how to eradicate the rodents, which are as big as small dogs and breed as fast as rabbits. If they take hold, wardens said, nutria could wreak a lot of havoc. 

"They burrow in dikes and levees and roadbeds so they weaken infrastructure. They're problematic for flood control systems," said Peter Tira, spokesman for the California Fish and Wildlife.

Native to South America, nutria can reach up to 2.5 feet in body length and 20 pounds in weight. The formal name for these rodents is "Mapudungun koypu" or "Myocastor coypus" derived from the two Greek words "rat" and "beaver." In Spanish-speaking countries, the word "nutria" often means "otter."

A female nutria can give birth to more than 200 offspring within a year of reaching reproductive maturity.

The problems associated with unchecked nutria have played out in other parts of the country, including Louisiana and the Chesapeake Bay region, according to Nutria.com. With no natural predators around, rodent numbers in these places have multiplied into the tens of thousands. Huge packs have dug up hills and riverbanks and mowed down marshlands.

In some spots, nutria have contaminated drinking water supplies. The animals can transmit parasites and disease to humans, livestock and pets.

Nutria were brought to California in 1899, according to the Department of Fish and Wildlife. When they escaped from fur farms and began living in the wild, state officials opened a campaign to eradicate the vermin. The rodent was believed to have been killed off in the 1960s.

State officials aren’t sure why the animal is back, but one theory ascribes the re-emergence to a remnant colony that lived off the radar in an isolated pocket of Stanislaus County.

The Associated Press contributed to this report.