Rattlesnake Removal and Control Methods
General Biology, Reproduction, and Behavior
When a rattlesnake strikes its prey or enemy, the paired fangs unfold from the roof of its mouth. Prior to the completion of the forward strike motion, the fangs become fully erect at the outer tip of the upper jaw. The erectile fangs are hollow and work like hypodermic needles to inject a modified saliva, the venom, into the prey. Rattlesnakes can regulate the amount of venom they inject when they strike. Mature fangs generally are shed several times a season. They may become embedded in the prey and may even be swallowed with the prey. When one mature fang in a pair is lost, it will soon be replaced by another functional mature fang. A series of developing fangs are located directly behind one another in the same sheath at the roof and outer tip of the mouth. If a newly replaced fang is artificially removed, it may require weeks or longer before another replacement will be fully effective. One fang can function, however, while the other in the pair is being replaced. Fangs that get stuck in a person’s boot are not very dangerous; they cannot contain much venom since they serve only as a hollow needle. The external opening of the hollow fang is a groove on the outside of the fang, set slightly back from the tip to prevent it from becoming plugged by tissue from the prey. Rattlesnakes cannot spit venom, but the impact of a strike against an object can squeeze the venom gland, located in the roof of the mouth, and venom may be squirted. This can happen when a rattler strikes the end of a stick pointed at it, or the wire mesh of a snake trap. The venom is released involuntarily if sufficient pressure is exerted, as occurs when venom is artificially “milked” from live snakes. Such venom is dangerous only if it gets in an open wound. Always wear protective clothing when handling rattlesnakes. Female rattlesnakes are ovoviviparous. That is, they produce eggs that are retained, grow, and hatch internally. The young of most species of rattlesnakes are 6 to 8 inches (15 to 20 cm) when born. They are born with a single rattle or button, fangs, and venom. They can strike within minutes, but being so small, they are not very dangerous. Average broods consist of 5 to 12 young, but sometimes twice as many may be produced. The breeding season lasts about 2 months in the spring when snakes emerge from hibernation. Sperm is thought to survive in the female as long as a year. During summer, pregnant females usually do not feed, so few are ever captured that contain eggs about to hatch. The young are born in the fall. Most rattlesnakes are mature within 3 years, but may require more time in northerly areas. Rattlesnakes may not produce young every year. The sex of a rattlesnake is not easy to determine. Even though the tail of the rattlesnake (the distance between the vent and the rattles) is quite short, it is much longer in males than in females of the same size. The paired hemipenises of male snakes are nor visible except during mating, when one of these paired organs is turned inside out and extruded from the cloaca. If both are extruded artificially, they appear like two forked, stumpy legs. Snakes never close their eyes, since they have no eyelids. They are deaf, but can detect vibrations. They have a good sense of smell and vision, and their forked tongues transport microscopic particles from the environment to sensory cells in pits at the roof of the mouth. A rattlesnake uses these pits to track prey it has struck and to gather information about its environment. Snakes have a large number of ribs and vertebrae with ball-and-socket joints. Each rib is joined to one of the scales on the snake’s underside. The snake accomplishes its smooth flowing glide by hooking the ground with its scales, which are then given a backward push by the ribs. Rattlesnakes often look much larger when seen live than after they have been killed. This happens because their right lung extends almost the full length of the tubular body, and when the snakes inhale they can appear much fatter and more threatening. The expulsion of the air can produce a hiss. Rattlesnakes, like other snakes, periodically shed their skin. When the new skin underneath is formed, the snake rubs its snout against a stone, twig, or rough surface until a hole is worn through. After it works its head free, the snake contracts its muscles rhythmically, pushing, pulling, and rubbing, until it can crawl out of the old skin, which peels off like an inverted stocking. Each molt produces a new rattle. Some rattles usually break off from older snakes. Even if no rattles have been lost, they do not indicate exact age because several rattles may be produced in one season. Even though the optimum temperature for rattlesnakes is around 77 degrees to 89 degrees F (25 degrees to 32 degrees C), the greatest period of activity is spring, when they come out of hibernation and are seeking food. If lizards are active, be alert for rattlesnakes. The activity period for rattlers can vary from about 10 months or so in warm southern regions to perhaps less than 5 months in the north and at higher elevations. Depending on availability of good, dry denning sites below the frost line, rattlesnakes may hibernate alone or in small numbers. However, sometimes they den in large groups of several hundred in abandoned prairie dog burrows or rock caverns, where they lie torpid in groups or “balls”. All dens must be deep enough so the temperature is not affected by occasional warm days. If not, the snakes might emerge too early in spring only to become sluggish and vulnerable should the weather again turn cold. Since snakes are cold blooded animals and their body temperature is altered by air temperature, refrigeration makes them sluggish and easy to handle for displaying. Rattlesnakes usually see humans before humans see them, or they detect soil vibrations made by walking. They coil for protection, but they can strike only from a third to a half their body length. Rattlers rely on surprise to strike prey. Once a prey has been struck, but not killed, it is unlikely that it will strike again. Experienced rodents and dogs can evade rattlesnake strikes.
Damage and Damage Identification
The greatest danger to humans from rattlesnakes is that small children may be struck while rolling and tumbling in the grass. Only about 1,000 people are bitten and less than a dozen die from rattlesnake venom each year in the United States. Nevertheless, it is a most unpleasant experience to be struck. The venom, a toxic enzyme synthesized in the snake’s venom glands, causes tissue damage, as it tends to quickly tenderize its prey. When known to be abundant, rattlesnakes detract from the enjoyment of outdoor activities. The human fear of rattlesnakes is much greater than the hazard, however, and many harmless snakes inadvertently get killed as a result. Death from a rattlesnake bite is rare and the chance of being bitten in the field is extremely small. Experienced livestock operators and farmers usually can identify rattlesnake bites on people or on livestock without much difficulty, even if they did not witness the strike. A rattlesnake bite results in almost immediate swelling, darkening of tissue to a dark blue-black color, a tingling sensation, and nausea. Bites will also reveal two fang marks in addition to other teeth marks (all snakes have teeth; only pit vipers have fangs too). Rattlesnakes often bite livestock on the nose or head as the animals attempt to investigate them. Sheep, in particular, may crowd together in shaded areas near water during midday. As a consequence, they also are frequently bitten on the legs or lower body when pushed close to snakes. Fang marks and tissue discoloration that follows in the major blood vessels from the bite area are usually apparent on livestock that have been bitten.