Communication Between Snakes

Snakes are well suited to analyzing the chemical cues around them via their sense of taste, smell and most importantly, their highly-developed vomeronasal system. The Jacobson’s organ is the primary component of the vomeronasal system. Located in the roof of the mouth, the Jacobson’s organ has two openings for chemicals to enter; one for each tip of the bifurcated tongue. When a snake flicks its tongue, it is collecting chemicals from the environment and inserting them in the Jacobson’s organ. The two openings of the organ allow snakes to smell their world “in stereo,” and determine if an odor is coming from the left or right. Snakes use their vomeronasal system to track prey, smell approaching predators, and to communicate with other snakes by collecting the chemical cues that they emit.

Snakes leave a trail of chemical cues in their wake, and among the most important of these chemicals are pheromones. Most snake pheromones are lipids that are left directly on a substrate, but a 2011 study by Rick Shine of the University of Sydney, published in The Royal Society’s “Biology Letters,” showed that at least one pheromone is airborne and can be perceived at a distance. By leaving, collecting and analyzing pheromones, snakes can communicate their gender, age and reproductive condition with other snakes. Juvenile red-sided garter snakes (Thamnophis sirtalis parietalis) are known to follow pheromone trails left by adults as they seek out communal winter dens. Additionally, red-sided garter snakes have complex mating behaviors; many males may surround a larger female in what is termed a “breeding ball.” While these snakes each vie for the female’s approval, some of the males engage in trickery; some of the garter snakes emit female hormones to confuse their competitors.

The males of some snake species are antagonistic towards one another; to communicate his dominance, a male may engage in combat with another male. This behavior and attitude is most pronounced during the breeding season, especially when a female is nearby. Combating snakes usually try to achieve higher physical position than their opponent, sometimes trying to push their opponent’s head to the ground. At times, combat can escalate and the snakes may bite each other, though bouts usually don’t result in serious injury or death.

Male snakes may twitch, jerk or make similar movements when ascertaining the receptivity of a female. These movements are likely an attempt to elicit approval from the female. In some cases, female snakes will lift or wave their tail when receptive.

While many snakes hiss or rattle their tails at predators, snakes are typically regarded as being deaf to airborne sounds. King cobras (Ophiophagus hannah) may challenge these assumptions though. King cobras emit a hiss that is much lower in frequency than most snake hisses, and is often called a growl. Additionally, king cobras are known to build rudimentary nests for their eggs, defend the nests from predators, and uniquely among snakes, employ both genders to guard the eggs. The combination of the growl and complex social interactions has led some scientists to investigate the possibility that these snakes communicate with the growls.