The victim, who hasn't been identified, was recovering at a hospital Sunday after undergoing emergency surgery.
California Department of Fish and Game Lt. Patrick Foy says the man was camping near a highway west of Perris when he was mauled Saturday night.
Foy told the Riverside Press-Enterprise (http://bit.ly/1k1Y4T3) the man didn't know what attacked him, but puncture wounds and cuts to his body indicate he was mauled by a big cat.
The attack prompted wardens to set up traps in the area. Foy said mountain lions typically return to the scene of a kill 24 to 48 hours later so they can continue feeding.