How close is too close? How far is far enough?
A rattlesnake’s potentially lethal bite argues strongly for remaining well beyond its reach, but just how close must a person be to place himself within range of a striking snake? As in most situations involving animals, the answer varies and in this case depends largely on the size of the snake, how it is positioned and the slope of the terrain in which one meets it. Knowing a few basic principles about why and how rattlesnakes strike can markedly reduce the chance of being bitten.
Rattlesnakes bite for just two reasons to capture food and defend themselves. Their venom’s primary offensive function is killing the prey these slow, heavy bodied, non-constrictor hunters could not otherwise catch. Secondarily, a venomous bite may be employed as a defense against perceived threats.
Rattlesnakes can and will bite from any position, but their fastest, most accurate strikes are unleashed from coiled or partially coiled stances. When reacting to being stepped on or grabbed, for instance, an uncoiled snake simply turns and bites, usually targeting the closest part of the offending mass. Deliberately timed and aimed strikes tend to be faster and more precisely placed.
Despite all their bad press, rattlesnakes are normally timid creatures avoiding most animals except intended prey whenever possible. But if sufficiently disturbed or threatened these snakes can quickly become aggressively defensive, and may stand their ground with a tenacity that mistakenly leads many people to believe they are innately mean-tempered.
When threatened, a rattlesnake typically draws its body into a defensive coil, holding about the forward third of its length in a tight, roughly S-shaped loop above its remaining mass. The coil initially collects the snake’s body into a relatively small area, making it easier to defend than when stretched out, and simultaneously provides a stable platform from which to launch a strike should one be deemed necessary. The snake’s head constantly faces its adversary, its body shifting as necessary to maintain visual contact if the threat attempts to circle.
The snake will probably attempt to warn away the interloper by vigorously shaking its namesake rattle, but nothing compels it to do so. It bears noting that the rattle, which consists of interlocked segments of dry skin, is fragile and frequently broken, and may thus be too short to be easily heard. Similarly, a rattle on a small snake may be incapable of creating sufficient noise to be readily heard. Don’t assume a rattlesnake will warn you of its presence!
Strikes occur when the snake releases the S loop in an instantaneous thrust at its target. During the strike the snake’s mouth opens, positioning its fangs to stab. It may or may not inject venom, depending upon how serious it considers the threat. Twenty to forty percent of initial, defensive strikes are “dry,” meaning little or no venom is released. Subsequent strikes are less likely to be so benign.
Ordinarily, a strike can cover a distance of between about one third and one half the snake’s length. Thus, as a rule of thumb, a three foot (1 meter) snake has about an eighteen inch (0.5 meter) strike radius; a four footer (1.3 meter) might reach out about two feet (0.6 meter), and so on.
Rattlesnakes cannot jump. If striking downhill, however, gravity and the momentum generated by a strike may combine to carry the animal farther forward than would occur over flat ground. On very steep slopes, a snake could lose balance during a strike and actually fall toward its target. Thus, the effective range of a downhill strike may exceed that normally expected across a level surface.
In Nevada, rattlesnakes rarely exceed lengths of four feet (1.3 meters). Simply by keeping at least that distance or roughly the length of whatever rattler you meet between you and it, your chance of being bitten falls to near zero.
Alex L. Heindl
Curator of Herpetology
Marjorie Barrick Museum of Natural History
University of Nevada, Las Vegas 89154-4009