Tail vibration

Tail vibration is a common behavior in some snakes where the tail is vibrated rapidly as a defensive response to a potential predator. Tail vibration should not be confused with caudal luring, where the tail is twitched in order to attract prey. While rattlesnakes are perhaps the most famous group of snakes to exhibit tail vibration behavior, many other snake groups—particularly those in the Colubridae and Viperidae families—are known to tail vibrate.

Tail vibration involves the rapid shaking of the tail in response to a predatory threat. The behavior is particularly widespread among New World species of Viperidae and Colubridae. However, some Typhlopidae and Boidae species may also tail vibrate. At least one species of lizard—Takydromus tachydromoides—has been shown to tail vibrate in response to a potential predator.

Tail vibration behavior in rattlesnakes is somewhat different from tail vibration in other snakes because rattlesnakes hold their tails vertically when tail vibrating, whereas other snakes hold the tail horizontally. Presumably, this is because the rattlesnake rattle produces its own noise, whereas snakes without rattles must vibrate the tail against the ground or some other object in order to make noise.

The speed of tail vibration is directly correlated with temperature, at least for rattlesnakes. The warmer a rattlesnake, the faster it vibrates its tail. Rattlesnakes tail-vibrate faster than other snakes, with some individuals nearing or exceeding 90 rattles per second. This makes rattlesnake tail vibration one of the fastest sustained vertebrate movements—faster than the wingbeat of a hummingbird. The movement is possible thanks to specialized “shaker” muscles in the rattlesnake tail.

Snakes more closely related to rattlesnakes vibrate more quickly than do more distant rattlesnake relatives. In one study that measured tail vibration 155 snakes representing 56 species, vibratory speed ranged from 9 vibrations per second (Bothriopsis taeniata) to 91 rattles per second (Crotalus polystictus). In the study, only two rattlesnakes (of 33 individuals filmed) had a maximum vibratory rate slower than the fastest non-rattlesnakes. The fastest non-rattlesnakes examined were species of Agkistrodon and New World Colubrids, both of which could sustain vibratory speeds up to about 50 rattles per second.

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Wikipedia