Gene Penaflor and a hunting buddy hiked into the Yuki Wilderness of the forest on Sept. 24. He told his family that he and his friend separated before he slipped and lost consciousness in steep terrain.
A four-day search that started the next day was called off after no clues to his whereabouts surfaced.
"He ate squirrels, whatever he could catch," said his son, Jeremy Penaflor. "He ate lizards, he ate a couple of frogs, he ate snakes, and survival mode kicked in. When you have no food for 18 days, whatever protein you can get, he did."
Penaflor used dry leaves and a heavy-duty garbage bag to stay warm.
A group of hunters and a search team from the Mendocino County Sheriff's Office found Penaflor on Saturday.
(The Associated Press contributed to this report)