California eradicated these 20-pound rodents decades ago; DNA suggests someone deliberately brought them back

Nutria (representative image) California once believed it had beaten nutria. The invasive semi-aquatic rodents had been wiped out in the state by the late 1970s, but decades later they reappeared in the Central Valley and a new genetic study suggests their return was not an accident of nature, but the result of human reintroduction.The finding matters because nutria are not just another nuisance species. They can damage wetlands, weaken levees, and destroy native vegetation and crops, which is exactly why California has spent years trying to remove them again.What nutria areNutria, also known as coypu, are large South American rodents that are built for water. Adult nutria typically weigh about 15 to 20 pounds, have a stout body, partially webbed hind feet, and a heavy rat-like tail covered in bristly hairs.They are often mistaken for beavers or muskrats, but nutria are a separate species with their own ecological problems. USDA describes them as semi-aquatic animals that thrive in marshes, canals, rivers, drainage ditches and other water-rich habitats.Nutria Why they became a problemNutria were first brought to the United States in the late 1800s for their fur, and when the fur ma...