Which sentence does not contain an adverb? They usually live in the southeastern United States and eat rabbits, rodents, and birds. The eastern diamondback rattlesnake is the largest poisonous snake in the United States. Like many other rattlesnakes, they frequently make a buzzing sound with the rattles on their tails when they feel threatened. Eastern diamondbacks grow as long as eight feet, with the average length often being two to six feet.