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David Attenborough is searching for timber rattlesnakes in a North American forest. He finds one basking on the forest floor, before it then heads off looking for somewhere to conceal itself and wait for prey to come within striking distance. A chipmunk is nearby, but the rattlesnake can't move fast enough to chase it. However, small mammals tend to use the same paths again and again along the forest floor, and they leave behind them a trail of scent that the snake can detect with its flickering tongue. The snake can also detect whether a mammal is nearby by using the heat detectors in the two pits beneath its eyes. As it slowly moves across the forest floor it carefully keeps its rattle off the ground so as not to make a noise. Finally it finds a place next to a tree stump where it is nicely camouflaged. As many scientists have watched rattlesnakes for years and not seeing one catch its prey, David is using the very latest in surveillance equipment: remote controlled cameras, infrared lights on stands, and motion detectors that will switch on the cameras if anything moves. David is then able to replay the footage later and watches as the rattlesnake waits patiently by a mouse's trail and then finally lunges at it, throwing its prey up in the air. Knowing that the venom will have killed it in seconds, the snake can take its time to find the body and swallow it whole.