Western Diamond-backed Rattlesnake

Feeding coil is something that sit and wait predators do. They just sit motionless in a coil, and wait for something to walk by (generally a rodent), then when it does, they strike at it. In this case, since he has venom, after he bites the animal he waits a little while then follows the heat trail it leaves behind (every vertebrate will leave a heat trail, and snakes can sense this) and the venom will have killed the animal, then he just eats it. Many of the larger, heavy-bodied snakes are sit and wait predators, and they will stay in feeding coils for weeks if necessary. They don't require as much food because they aren't out being active looking for food, which uses a lot of energy.