Best guess is this is a Californian Whipsnake with a Deer mouse but I'm not really sure. However, I can say that to the best of my knowledge it's one extremely lucky mouse! I walked a trail littered with rattlesnakes. Yet in the midst of all those deadly venomous snakes, this mouse got bit by this non-venomous guy instead. The snake was coiled around and preparing for lunch just as I walked up. It froze in panic staring at my and dropped the mouse. Though I did the best I could at keeping my distance, the snake was just to nervous. It bought that mouse a few minutes to recover. It may still have been a fatal bite from damage alone, but the mouse looked like it was fine as it walked off safely!
Carrizo Plain, California April 2011