A few years ago, I was visiting my parents near San Francisco when talk turned to their compost bin. They thought they had snakes living in it because they'd seen something long and skinny moving around in there. Well that was intriguing so I got the pitchfork, opened the bin, and started digging around. I saw something too, and dug a little more. To my surprise, not a snake, but a rat made a 3 foot high vertical leap (right next to me), jumped out of the compost bin, and ran away. My mom must have only seen the rat's tail and mistook it for a snake.
So when I saw something moving in my compost bin today, I was disappointed. Figured I had rodents - what a pain. But I stared into the bin a little longer, and saw it was a cute little lizard (the kind that I see sunning and running on my retaining wall all the time). Wonder if he's eating the bugs or the plants or both.