If it was cold, it might have been drawn to the heat of the engine.
Our resident pair of garter snakes started a family. I saw a tiny snake yesterday morning—cute if you like snakes.
Garter snakes are vivaporous: the young develop in the mother's body and are born fully formed rather than as an egg. The babies eat worms, slugs, and all sorts of little bugs. Not a bad critter to have in the garden.
