AmphibiansReptiles
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Timber Rattlesnake (Crotalus horridus)
Description
The background coloration may vary from a dark slate-gray, to a silverish gray, to tan, to brown. Even individuals within the same population may look strikingly different from one another in this regard. As with all of the pit vipers that occur in Arkansas, the Timber Rattlesnake has a boxy-shaped head, heat-sensing pits, and vertical pupils. The young of a Timber Rattlesnake may look in many ways similar to a Pygmy Rattlesnake. However, the Pygmy Rattlesnake has a strongly patterned head and relatively smaller rattle in comparison to body size. This species is also known as the Canebrake Rattlesnake or Velvet-Tail Rattler.  HabitatsThis snake has typically been associated with rugged, rocky, remote, and heavily forested areas. However, after Timber Rattlesnakes disband from their den sites in the Spring, they may utilize a variety of habitats, including cedar glades, grassy fields, and areas of sumac and thick brush. Habits and Life HistoryIn Arkansas, Timber Rattlesnakes typically hibernate in relatively fewer numbers per den location than in other parts of their range (especially to the north). Den sites may house an estimated 1-20 adult snakes. These locations are usually West- or South-facing bluffs or other rocky outcroppings. Animal burrows may also be used as dens. Emergence from hibernation occurs in mid-Spring. It seems these snakes have two main strategies for regulating body temperature during this time of the year when temperatures can vary greatly, especially night-time temperatures. One is to stay near the den location and utilize rock crevices. A large rattlesnake that exposes only a small portion of its body to sunlight from underneath a rock crevice can raise its overall body temperature significantly. Should the temperature drop too much, the snake can simply retreat deeply into the crevice. The other strategy is to move further away from the den site into the surrounding woodland. Once there, the snake can vary the amount of itself it hides under leaf litter for the same purpose of regulating body temperature. On a cool day and at night, the snake may hide itself completely under a blanket of leaves. Before too long, the temperatures have warmed up and Timber Rattlesnakes begin their summer foraging routines. The area where a snake selects for foraging may be some distance away from the den site. Many Timber Rattlesnakes, over the course of a summer, will show clear large-movement patterns. Often this pattern is a "loop" that the snake will make 3-5 times during the course of a season. Others are even more predictable and will return to an exact hunting-spot repeatedly. Males will usually venture further away from the den site than females. Mating behaviors are observed in the late summer and early fall. In years of particularly high food abundance, mating starts earlier. In years of low abundance, there may be no mating at all. Males will make several long straight-line searches for the scent of a female. In Timber Rattlesnakes there seems to be a strong linkage between the shed cycle of a female and mating behaviors. A male who locates a female deep into a shed cycle will stay with her until she sheds. He may even coil right over the top of her, protecting his claim. He will battle other males for dominance should they approach. A battle between two male rattlesnakes is a ritualistic wrestling match in which one male tries to push and keep the other male pinned down to the ground. No biting is involved and injuries are extremely unlikely. The winner is determined by size and endurance and he will have the opportunity to mate with the female. After the female sheds, actual mating takes place and the snakes go their separate ways. Although females appear to take a more passive role, forced copulation in snakes is impossible and so the female ultimately decides whether or not to mate with a particular male. Females who have mated the previous Fall follow a slightly different course of action. Over the winter, the female simply stores the male's sperm. This sperm may actually be retained for several years. In early Spring, she fertilizes 5-8 eggs. (Should conditions prove difficult, she may actually abort the pregnancy and reabsorb the fats and proteins of the developing eggs.) As Summer turns to Fall, she will seek out warmer microhabitats in order to complete the development of her eggs. Finally, in mid-Fall, she will give birth. Each baby is born in a shell-less egg and within a few minutes after birth cuts through the clear outer membrane with their "egg tooth". The female and her young will not stray far from the birthing area for a week or more. As the night-time temperatures begin to drop significantly, Timber Rattlesnakes make their way back to their den sites. Almost always, the den site for a snake will be the same one it used the previous winter. The snakes that are in the best physical condition typically den earlier. Those snakes that have had difficulties getting enough food for the year may stay out foraging very late into the year, even tolerating cold mornings that cover them with frost. It is presumed that the newborn snakes follow the scent of their mothers in order to find a suitable den site. Once deep into their den site, Timber Rattlesnakes don't simply coil in a spot and remain motionless for the entire winter as one might suspect. Although much still needs to be learned, it is known that Timber Rattlesnakes frequently move from place to place underground during the course of a winter. There are a number of possible explanations for this. One is that it helps to reduce the number of "hibernation sores". Another is that the snakes are thermoregulating to some extent or perhaps regulating humidity by moving between wetter and drier microhabitats. Prey and Hunting TechniquesTimber Rattlesnakes are sit-and-wait predators. They search carefully for a spot with recent rodent activity and position themselves for prey to come within striking distance. Typically, the location where a Timber Rattlesnake coils in foraging posture looks, at a passing glance, just like most of the rest of the forest: deciduous leaf litter, various scattered twigs and small logs. A snake may coil with its body completely covered with leaves, or not covered at all, but typically buries itself with about 10-60% leaf coverage. Many times, after a snake has been discovered in foraging posture, a close inspection of the surrounding leaf litter reveals lots of rodent activity. Sometimes, a Timber Rattlesnake is much more obvious about its hunting strategy. It is not uncommon for them to coil directly beside a deer trail, where, it is presumed, many rodents will also pass. At other times, they may coil at the base of a tree, sometimes even resting their chin upon the trunk. For any rodent going up or down the tree, this will prove to be a dangerous proposition. Another similar strategy utilized more often is for a Timber Rattlesnake to coil directly beside a fallen log with their chin resting upon the log. Any rodent that uses the log as a "runway" through the forest will create vibrations that will forewarn the snake to prepare to strike. A few Timber Rattlesnakes (more often females than males) that seem to prefer avian prey, will even climb high into trees. Usually they will find an old knot or hole in which to coil, but other times they will take to the limbs and "stretch out" up to 10 meters (33 feet) above the forest floor! Before striking its prey, a Timber Rattlesnake demonstrates care and precision. It will not strike "blindly". Each potential prey is "sized up" to determine if it is the right kind of prey that is neither too small nor too large for the snake. Only after this, the prey is very quickly struck, envenomated, and released. (A Timber Rattlesnake that strikes a bird high in a tree may actually hold onto its prey and not let go. Should the bird fly away, even a short distance, it would be almost impossible for the snake to track it down.) Timber Rattlesnakes will meter the amount of After a Timber Rattlesnake has envenomated its prey, it will wait from 1 to several minutes before beginning to track it down. The tracking abilities of a Timber Rattlesnake are amazingly attuned. In fact, as lab studies have demonstrated, should the scent of the prey a snake is tracking be crossed with other scent trails of the same prey-type (even with prey that has been envenomated by other Timber Rattlesnakes), the snake will not err in tracking only the precise prey that it struck itself! Upon locating the prey, that has now succumbed to the After the prey has been completely swallowed, a Timber Rattlesnake will simply rest for quite some time. Once it has enough strength, it will move to a sunny and warm microhabitat where it will digest its meal over the course of several days. One very large meal may be the only food a Timber Rattlesnake needs (or gets) for an entire year! Timber Rattlesnakes eat a variety of rodents, such as mice, rats, chipmunks, and squirrels. They may also eat small rabbits and various kinds of birds. Temperament and DefenseTimber Rattlesnakes are shy and gentle. They almost always live peaceably with humans because humans almost never see Timber Rattlesnakes, even when the snakes are stepped directly beside or sometimes even stepped directly on! Timber Rattlesnakes are superbly camouflaged and rely on this as their primary means of defense. They hardly ever rattle and are even less likely to strike in defense (although we shouldn't assume that rattling will always precede a defensive strike). At least with human encounters, Timber Rattlesnakes that rattle (or even move) generally don't fare well. I think many times a human hears a rattling Rattlesnake as saying, "Hey you, come over here and beat me to death with a stick." And, for some reason, vehicles seem to be "magnetically attracted" to snakes, often times swerving far and wide to hit as many snakes as possible. I have found that about the only time a Timber Rattlesnake will rattle is when it is approached very closely when it is on the move or when it is "bothered", such as when it is tonged and placed into a bucket. I believe these are times when a Timber Rattlesnake feel exposed and vulnerable. The defensive display of a Timber Rattlesnake is less exaggerated than that of some western species of Rattlesnake, such as the Western Diamond-backed Rattlesnake. A Timber Rattlesnake will generally coil into a defensive position low to the ground, rather than raising the front part of its body high off the ground. Although it usually takes some doing to get a Timber Rattlesnake to begin rattling, once they start they may continue to rattle for some time, even after the obvious danger has passed. Along with rattling, a Timber Rattlesnake may also hiss loudly (if you can hear it over the rattling). Finally, they may also emit a foul-smelling musk (a common defensive maneuver for many species of snake). Timber Rattlesnakes are preyed upon themselves by many natural predators, such as hawks, bobcats, coyotes, and bears. As a final note, I often hear people tell stories about some snake that was "the meanest thing ya' ever did see...that was striking at me like crazy." I always ask if this snake acted this mean before or after it was beat half to death with a stick. Snakes, and Timber Rattlesnakes in particular, already have the right behaviors to live peaceably with humans. After working closely for several years with Timber Rattlesnakes, I can say with some assurance that they are entirely uninclined to confront any human, entirely uninclined to strike in defense, entirely uninclined to have anything to do with humans, and entirely inclined to live their lives without the dangers imposed by humans. We are the ones who need to change behaviors, to learn to appreciate the beauty and intrigue of these spectacular predators! ConservationThis species currently has no special protections in Arkansas. However, because of its fragile state of existence in the Northern part of its range, it may soon be afforded federal protections. The greatest threat to this snake in the state is assuredly human activity. The clearing of woodland to make fields for cattle, the construction of high-speed highways, the sprawl of towns and cities, and the increasing number of human visitors to wilderness areas are all especially harmful to this species of snake. Timber Rattlesnakes are long-lived animals (with a natural life-span of perhaps 20-25 years). They are slow to mature and females may be able to breed only once every three years. Therefore, the needless killing of a single adult female may be enough to definitely impact a population in a particular area. State Distribution and Abundance
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Discussion< Western Diamond-backed Rattlesnake | Snake | Western Pygmy Rattlesnake > |
This large-bodied 