|MadSci Network: General Biology|
The short answer is that it depends. If you go to Yahoo and look under nocturnal and snake, you'll get lots of sites describing nocturnal snakes. I do know that the Rat Snake, which is common throughout America, including Virginia, is known to be nocturnal.
Snakes are predators, and usually eat things like small rodents and reptiles- it so happens that many rodents and reptiles are nocturnal. So for a hungry snake, they can either find their prey during the day while it is asleep (something that some snakes are very good at), or go hunting at night. In fact, one family of snakes, the pit-vipers (which includes rattlesnakes and cottonmouths) have specialized organs (found inside the pits on the lateral side of their head, for which they are named) that can sense infrared (IR) light. The snakes cannot "see" IR light, because the facial pits are not eyes; the closest analog to what they are doing is "smelling" IR light. Because a warm body emits IR light, the pit vipers can use these organs to help them detect prey when they are hunting, be it at night or in a dark burrow.
Snakes are also cold-blooded, which means that their metabolism depends on the ambient temperature of their environment. This means that if it's cold out, a snake will not be able to move very fast, and will thusly have a hard time hunting. So, in temperate areas, you might only expect snakes to be nocturnal in the summer, when it's warm enough for them at night. This could also explain why nocturnal snakes are more common in tropical areas.
Rob Campbell, MAD Scientist.
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