This Is the range of L.z. zonata, the Saint Helena Mtn. King. They have been reported from the areas around Lake Sonoma and the Geysers just north of your location.. Unconfirmed reports of sightings as far south as Mt. Tam. in Marin Co. Last year someone told me he witnessed a zonata eating a juvenile Gopher snake in the hills above Petaluma. He knew little about snakes but claimed that the snake was a tricolor and not a common king.