For almost 100 years the red foxes were thought to have escaped from fur farms and hunting parties in the 1900s, but they're actually genetically different than non-native foxes elsewhere in California, The Sacramento Bee reported Saturday.
They are also genetically distinct from gray foxes native across most of California, the newspaper said.
Ben Sacks, a biology professor at the University of California-Davis, says genetic testing shows the subspecies, which he calls the Sacramento Valley red fox, is unique to lowland areas north of the American River and the Sacramento-San Joaquin Delta.
"We can now say that the foxes of the Sacramento Valley are native to California," Sacks said. 
"The fact that the evidence is pointing toward it as a native species -- and a native species that we didn't know about -- is kind of an amazing development," said Armand Gonzales, a wildlife program manager at the California Department of Fish and Game. "That doesn't happen very often."