Here at the UC Hopland Research & Extension Center in southeast Mendocino County, the Northern Pacific Western Rattlesnake (Crotalus viridis oreganus) is rather common.   Construction workers have encountered four during the building project of the new Rod Shippey Educational & Field Lab facility.  And, the other day one was coiled up near the front door of the main office building.

No matter what the age or size of the rattlesnake, all can be identified by the wide, triangular head, vertical eye pupils, narrow neck, stout body, and strongly keeled scales.   Here you see a fairly young one about 14 inches long ... probably a one-year-old juvenile.