While rattlesnakes are well-known for their distinctive sound, many other snake species also vibrate their tails when threatened. This defensive action is a widespread strategy to deter potential predators. This article explores the biological purpose behind these tail vibrations and identifies common non-rattlesnake species that employ this mimicry.
The Purpose of Tail Vibrations
Tail vibration in snakes functions primarily as a defensive mechanism. When a snake senses danger, it rapidly shakes its tail to create a sound intended to warn off threats. This behavior is particularly effective when the tail strikes against dry leaves, grass, or other debris, producing a buzzing or rustling noise. This sound can mimic the distinctive rattle of a rattlesnake, leading potential predators to believe they are encountering a more dangerous animal.
This mimicry is an evolutionary adaptation that increases the snake’s chances of survival. The vibration can also serve as a distraction, drawing attention away from the snake’s head and towards its less vulnerable tail. While rattlesnakes have specialized structures for this, many other snake groups, particularly in the Colubridae family, exhibit this defensive behavior.
Common Non-Rattlesnake Species That Mimic
Several non-venomous snake species commonly shake their tails when threatened, creating a sound similar to a rattlesnake.
Gopher snakes are found across North America, often with blotched patterns. When agitated, a gopher snake will coil, hiss loudly, flatten its head, and vigorously vibrate its tail against dry ground or leaves to produce a buzzing sound.
Bullsnakes, a subspecies of gopher snakes, also employ this tactic. These large constrictors are found in central North America. When cornered, bullsnakes coil defensively, hiss loudly, flatten their heads, and rapidly vibrate their tails, creating a convincing rattling sound if debris is nearby.
Kingsnakes, named for preying on other snakes, are another common mimic. These non-venomous snakes vary widely in appearance and inhabit diverse environments across North America. When threatened, a kingsnake vibrates its tail rapidly, often against dry leaf litter, generating a buzzing sound resembling a rattlesnake’s warning.
Corn snakes, popular as pets, also exhibit tail vibration. These slender snakes are native to the southeastern and central United States, typically displaying orange, red, and brown blotches. When startled, a corn snake rapidly shakes its tail against the ground, creating a sound to deter potential predators.
Rat snakes, including species like the black rat snake, are widespread across North America. When faced with a threat, rat snakes coil, hiss, and rapidly vibrate their tails. This action, especially when the tail contacts dry leaves or other substrate, produces a buzzing or rattling sound. Fox snakes, also found in central North America, similarly engage in tail vibration, creating a sound when their tail hits dry leaves.
Key Differences from True Rattlesnakes
Distinguishing between a true rattlesnake and a snake mimicking its behavior involves observing several key characteristics. The most definitive difference lies in the tail itself: rattlesnakes possess a unique, segmented rattle made of keratin at the end of their tail. This specialized structure produces a distinct, dry rattling sound when vibrated. Mimicking snakes lack this rattle and must vibrate their tails against external objects like leaves or debris to create a similar sound.
Another distinguishing feature is head shape. Rattlesnakes, being pit vipers, typically have a broad, triangular head due to venom glands behind their eyes. Many non-venomous mimics, such as gopher snakes and bullsnakes, generally have more elongated or oval heads, though they can flatten their heads when threatened to appear more triangular. Observing pupils can also offer a clue; rattlesnakes commonly have vertical, elliptical pupils, while many non-venomous snakes have round pupils. However, pupil shape can be difficult to discern safely and may appear round in low light, making it an unreliable sole identifier.