Invasive Nutria Rodents May Have Been Deliberately Released in California

Wildlife experts believe the rodents were transported from Oregon, not migrated naturally.

Apr. 10, 2026 at 11:27pm

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A bold, highly structured abstract painting in muted tones of green, brown, and blue, featuring sweeping geometric arcs, concentric circles, and precise botanical spirals, conceptually representing the complex natural systems impacted by the invasive nutria rodent.An abstract visualization of the complex biological and ecological forces at play as the invasive nutria rodent disrupts California's natural habitats.Merced Today

State wildlife officials in California believe the sudden reappearance of the destructive nutria rodent in the state's wetlands may have been the result of intentional release, rather than natural migration. Recent genetic research suggests the nutria populations in California are closely matched to those in Oregon, making it highly unlikely they traveled the distance between the states on their own. Experts speculate the rodents may have been brought to California as a natural remedy for overgrown vegetation or simply because people liked them, though the exact reason is unclear.

Why it matters

The nutria is a major threat to California's agriculture and water supply, as the large rodents can eat a quarter of their body weight in vegetation and burrow destructively through waterways and ecosystems. The state has been battling the nutria's rapid spread and reproduction since they were first rediscovered in 2017, nearly four decades after they were considered eradicated.

The details

Since 2017, the California Department of Fish and Wildlife has removed 7,841 nutrias by trapping them or releasing other sterilized nutria back into the wild with tracking devices. Native to South America, nutrias were originally brought to the U.S. in the early 1900s to breed and reproduce for a fur trade that was never successful. The rodent was largely unseen until 2017, when a pregnant female was found in Merced County.

  • In 2017, a pregnant female nutria was found in Merced County, California.
  • Since 2017, the California Department of Fish and Wildlife has removed 7,841 nutrias.

The players

California Department of Fish and Wildlife

The state agency responsible for managing California's wildlife and natural resources, including the ongoing effort to remove the invasive nutria rodent.

U.S. Fish and Wildlife Service

The federal agency that has suggested hunting down and eating nutria as a way for Californians to help rid the state of the pest.

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What’s next

The California Department of Fish and Wildlife will continue its efforts to trap and remove nutria from the state's wetlands and waterways.

The takeaway

The sudden reappearance of the destructive nutria rodent in California highlights the ongoing challenge of managing invasive species, particularly when there are suspicions that the introduction may have been intentional. This case underscores the importance of vigilance and proactive measures to protect the state's natural resources and ecosystems.