Rattlesnakes, also known as pit vipers, vibrate the end of their tail to produce the tell-tale sound for which the snake is best known and for which the species is named. Experts believe the primary purpose of a rattlesnake rattler is to warn potential predators of the snake's presence, since rattlesnakes do not typically strike unless provoked. Other experienced researchers, snake handlers, and wildlife experts suggest the buzzing sound produced by a rattlesnake rattler has the additional purpose of mimicking insect sounds that attract prey animals. Although it does not serve a purpose to the snake, a rattlesnake rattler can also be used to determine an individual snakes' approximate age.
Contrary to popular belief, rattlesnakes seldom attack anything other than prey it intends to eat, unless provoked into mounting a defense. When approached, a rattlesnake will typically coil up in an effort to protect itself. By vibrating its tail and creating the rattling noise, the snake hopes to warn unsuspecting people or other predators of the intention to mount a venomous defense, if necessary. The rattlesnake rattler produces a distinct buzzing sound which most potential defense victims immediately recognize and associate with imminent danger. Natural response to a rattlesnake rattler sound, no matter the potential victims' species, is to avoid the poisonous snake at all costs, thus relieving the snake of the need to strike out in defense.
Alternatively, some researchers suggest that the buzzing sound associated with a rattlesnake rattler serves to attract select types of prey, helping the snake to lure prey rather than having to hunt for food. Certain species of rattlesnakes produce a sound that is reportedly similar to cicadas and other insects. Birds, lizards, and other animals hear the vibrating sound and follow it, expected to find food. Instead, prey stumbles into an ingeniously laid trap, with a rattlesnake patiently lying in wait for the prey to get within striking distance.
For researchers and those who study wildlife, the final purpose of a rattlesnake rattler is to determine the approximate age of an individual snake by counting the number of segments included in a rattle. A rattlesnake rattler begins as nothing more than a button on a baby rattlesnake, making almost no sound when vibrated. As the snake ages, additional rattles are added, giving the snake the ability to make a buzzing sound. Each time a rattlesnake sheds its skin, which can be two or more times per year, a new rattle segment grows. Unfortunately, it is not uncommon for a pit viper to loose portions of a rattle due to injury, so age estimates using rattler segments are far from conclusive.