Prairie Rattlesnake

By Steve Thompson

On This Page

| Hear the rattling sound of a snake | Dens & hibernation | Graphic - Find the snake | Snake food |

| Fangs & venom | Age of a rattlesnake | Snake identification | Precautions in snake country |

Snake Tongs | | Striking distance | Footwear | Snakebite statistics | Snakebite first aid |

My Other Pages

Unique Snake Gifts & Leather Products

Problems With Snakes: House & Yard

To see similar pictures like the above rattlesnakes, click your mouse over the bolded and underlined words. To hear the sound of a rattlesnake rattling, click your mouse on the below rattling sound phrase.

Various rattlesnakes species are found only in the Western Hemisphere from SW Canada to Argentina. 32 species and 83 subspecies of rattlesnakes are identified in the Americas. Crotalus has 29 species and 74 subspecies. Sistrurus consists of 3 species and 9 subspecies. South America has 9 subspecies of rattlesnakes. Mexico and Central America have 4 subspecies. Rattlesnakes can be found in a range of habitats and mountain elevations up to 14,000 feet. The timber rattlesnake was once found in both Rhode Island and the southern Maine, but has been exterminated from both states. Alaska, Delaware, and Hawaii have no records of rattlesnakes. Every other state has at least 1 species of rattlesnake.

The Western Rattlesnake (Crotalus viridis ) has one of the largest home ranges of rattlesnakes in North America. This rattlesnake or its subspecies can be found in the Canadian provinces and southward across the central United States to Mexico. In South Dakota, the subspecies is called the Prairie Rattlesnake (C. v. viridis ) and found 10-15 miles east of the Missouri River and western South Dakota, in the open prairies, haylands, and croplands -- any area with an abundance of food.

The rattles and their distinctive rattling sound are the most recognizable feature of this snake . The Prairie Rattlesnake is the only venomous snake native to South Dakota. Young rattlesnakes are born with a prebutton, a rattle segment at the tip of their tail. All other South Dakota snakes are born with a pointed tail. Rattlesnakes (along with copperheads and cottonmouths) are members of the Pit Viper family. The "pit vipers" have a triangular shaped head with a small cavity or pit on each side, between the eye and the nostril. They can sense warm-blooded prey in complete darkness up to 2 feet away. These thermoreceptor organs contain nerves that are sensitive to heat or warmth and can detect temperature differences within several thousandths of a degree.

The color of the Prairie Rattlesnake varies from light brown to green, with a yellowish belly. Dark oval blotches with light colored borders run along the center of its back. The blotches become crossbands on the back part of the body and rings around the tail. Adults will range in length from 30-40 inches, with a record of 57 inches. 3 foot rattlesnakes normally weigh 1 pound (a 54 incher weighed 4 1/2 pounds).

Many South Dakotans admit they have never seen a rattlesnake in the wild, even those in rattlesnake country. If they knew how many times they where within 10-15 feet of a snake, there would be many places they would never go back to. Use your mouse and click on this graphic to see if you can see the snake. The snakes are there; if you leave them alone, they will likely do the same to you. If you did not find the snake, click on this rattlesnake graphic to see the location of the snake lying outstreched in the grass. As seen with my graphic, snakes have a great display of camouflage. Most snakes are normally timid and secretive. When approached, they usually remain quiet to avoid detection. They may try to escape if given an opportunity. When frightened, cornered, or attacked, snakes will stand their ground and may attempt to strike at or bite their intruder.

There was an interesting article in the South Dakota Magazine (September/October 1991) "Rattlesnake Hunt at Mobridge". Several men went snake hunting on a prairie dog town on a warm fall afternoon. When the hunt was over, the men had killed over 400 rattlesnakes at this denning area. Most dens will average 250 snakes, but some dens have been reported to have up to 1,000 snakes of the different species, denning in the underground structure.

Rattlesnakes are cold-blooded or ectothermic animals. Their body temperature is influenced more by the temperature at the grounds surface where they are lying, rather than the air temperature. High or low temperatures cause the snakes to seek escape cover or shady areas. Most snakes cannot survive exposure to direct sunlight with temperatures over 100 degrees F, but rattlesnakes have a greater endurance to lower or freezing temperatures. Lethal temperatures for the snakes depend on the time of exposure. Unlike warm-blooded or endothermic animals, snakes are unable to produce their own body heat. To maintain a desirable temperature, snakes must rely the temperature or warmth of their surroundings. The snake's circulatory/nervous systems aid in controlling the warming or cooling of their body.

With the harsh winter conditions in the northern states, rattlesnakes need to find an underground refuge for the winter months. Early fall frosts and shortening daylight, encourage snakes to move toward the dens, normally found on hillsides, bluffs, and rocky outcrops with underground openings used as denning sites. Snakes will also den up in holes or burrow systems of prairie dogs or other animals. Any such underground hole, crevice, mammal burrow, or other retreat area must be deep and extend to a depth below the frost line. The dens are normally found on hillsides with a southerly sun exposure allowing for spring and fall basking in the sun. Preferred dens are found on higher elevations above creeks and drainages that may be prone to spring flooding. Snakes cannot dig their own holes, although they can push or root out material with their noses. Vacant holes left behind by other animals are often used as escape cover or denning over the winter months. The first freezing temperatures in the fall months, snakes start their movements toward the den and will congregate near the den until the lower temperatures drive them underground. In the late March or April, triggered by increasing ground temperatures, the snakes will move toward the ground surface or the den opening. With the warming nighttime temperatures and the prolonged period of sunlight, snakes leave the den to find food, mate, and have young during their summer travels. Throughout the summer months, the dens are abandoned and the snakes will travel 2-4 miles from their den. In a Wyoming study, radio transmitters were implanted in various snakes and one female rattlesnake traveled a distance of 8 miles from its den. Snakes return to the same den year after year, provided the den is not disturbed or destroyed. These dens or hibernaculums have been used by many generations of snakes over the years. Some people feel that snakes leave scent trails or pheromes to identify past travels. Other snakes, such as juveniles, may use their sense of smell to follow the odor or pheromes trails of adult snakes, to locate their dens.

All snakes are predators and must locate their prey before they seize it. A snakes vision can detect movement out to about 40 feet, closer objects are seen more sharply. Rattlesnake eyes are lidless, but are protected by a hard transparent covering or scale. The pupil or the black portion of a rattlesnake's eye is elliptical, not round as with the nonvenomous snakes such as the racer. The vision of many snakes is better suited for nighttime searching rather than daytime activity. The eyes initiate the visual prey response, then the senses of smell or thermosensitivity come into play.

Rattlesnakes and other snakes lack external ear openings, but snakes are not deaf. Their outer body scales and bones are sensitive to air or ground vibrations. Snakes have two senses of smell: 1) external nostrils, lined with olfactory cells for picking up various odors, but the nose is mainly used for breathing and 2) the forked tongue, is their primary sensory organ for smelling. The tongue is a sensory device for the Jacobson's (vomeronasal) organ. This chemoreceptive organ lies within paired cavities on the roof of the snakes mouth. The snake extends its tongue, to pick up microscopic airborne particles and gases from the air on the tongues surface. The tongue then transfers these order stimuli into the Jacobson's organ and later the brain identifies them as food, enemy, or a mate. The tongue is also used for tracking the snakes prey. The food eaten by a snake depends upon the animal's size and the environment where it lives. Rattlesnakes eat animals such as mice, ground squirrels, and the young of prairie dogs or cottontail rabbits. They also eat other snakes, lizards, birds, and insects. The average snake will consume 2-3 times its own weight in various food items during the spring to fall months when the snake is away from its winter den.

The snake's skeletal system consists of the skull and jaws (including teeth), a backbone, and ribs. The jaws flex (up to 1 1/2 times the jaw width) to allow snakes to swallow larger prey. All snakes have small-recurved teeth in both the upper and lower jaws. These teeth are not used to chew or tear food, but hold the food items and aid in swallowing. A snake swallows its prey in one piece.

Rattlesnakes have a pair of hollow fangs for delivering venom. These long, hooked structures fold against the roof of the mouth when not in use and point forward when the snake strikes its prey. The venom glands are located below and behind each eye, with a venom duct connecting to the front gum line of each fang. The Eastern Diamondback Rattlesnake has fangs up to 1 inch in length. The fangs of adult Prairie Rattlesnake, will be less than 1/2 inch in length. Fangs that are broken during feeding activities or striking, can also be replaced. The fangs are shed from alternate sockets of the paired maxillary bones on the front edge of the upper jaw. The full-sized replacement fang is aligned adjacent to its predecessor, providing 2 fangs on each side for a brief period. Rattlesnakes have a number replacement fangs, in various stages of growth, in the tissue behind the maxillary bones. These fangs and other teeth are replaced on a monthly schedule. Venom produced by the venom gland is an enzyme/protein complex and is one of the most dangerous natural animal poisons. Venom immobilizes and kills the prey, but also starts the digestive process. The quantity, strength, and characteristics of the venom vary from species to species. A larger snake has longer fangs, greater venom capacity, and a larger body to deliver more forceful strikes. The snake controls the amount of venom injected by the contraction of the muscles surrounding the venom glands. The venom of the rattlesnake is mainly a hemotoxin, affecting the blood and lymphatic systems causing pain and rapid swelling in the victim. Venom from such species as cobras and coral snakes is mainly a neurotoxin, which paralyze the nervous system, stopping breathing and heart action. The venom from some rattlesnakes may have both hemotoxin/neurotoxin characteristics.

The "striking distance" of snakes is much shorter than commonly believed. Cornered or threatened snakes may strike in all directions and from almost any position, giving the impression their striking distance is much greater than it actually is. The normal striking distance is 1/2 the snakes body length. The snake strikes rapidly and effectively by drawing its body into an S-shaped coil and striking forward.


A mutant - gold colored
Prairie Rattlesnake

The normal oval blotches along the back were absent

Note the black eye
and the red colored tongue

Also the orange coloration at the base of the tail area

All snakes are covered with scales, which are part of a colorless outer skin layer. Under this skin layer, is another layer that contains pigment cells that give a snake its distinctive color pattern. The arrangement of color patterns, type of scales, and scale rows are all used to identify the various species. Rattlesnakes have a keeled scale, that has a ridge on the center of each scale. Other snakes, such as racers and milk snakes have smooth scales - with no ridges. The skin of a snake is dry, not slimy. Molting or skin shedding is repeated periodically throughout a snake's life. 7-10 days prior to shedding, a fluid is formed between the outside layer of skin and the newly formed skin underneath, helping to loosen the skin for shedding. This fluid causes the eyes and base rattle segment to have a blue or cloudy appearance prior to shedding. The snakes vision is impaired during this time and the snake to go into a period if inactivity or hiding. Just prior to shedding, the eyes will clear and the snake will "crawl" out of its old skin, which peels backward over the body from the head to tail. The snakes skin is the most colorful and bright after the shedding. The outer portion of the shed skin, appears clear or translucent. An older snake may shed its skin 1-2 times a year, but a younger yet growing snake, may shed 3-4 times.

Most people believe that you can age a rattlesnake by the number of rattle segments. If the snake has seven rattle segments, it is believed to be seven years old (one rattle/year). This is not true, since a rattle segment is added to the tail area, with each shedding (2-4 times a year). Rattlesnakes are born with a rattle segment called a prebutton, at the tip of their tail. The juvenile rattlesnake normally sheds it skin within the first seven days after its birth. The prebutton is shed with the skin and replaced with a new underlying button. The shedding frequency depends on how much the snake is eating and growing. Skin shedding is required for the snakes growth and to replace worn skin. In the wild, the rattles get cracked and segments are often broken off. The rattle segments interlock together and are made of a keratin substance similar to horns, feathers, or our fingernails. Many older snakes have the button or other segments broken off and may have only 4-5 rattles remaining. Rattle segments that total 10 or more are rare, but some captive rattlesnakes have had 20+ segments. When frightened, the rattlesnakes use the muscles at the base of their rattles to vibrate or shake the rattle segments together, making the rattling sound - no sand, pebbles, etc. are within the rattles to produce this buzzing sound. Rattles of larger rattlesnakes are bigger and have more rattle segments, that can be heard rattling many yards away. Rattlesnakes don't always rattle prior to striking a victim, but only when threatened or endangered. Most rattlesnakes will stand their ground when cornered or provoked.

Most snakes (70%) are oviparous and lay an egg (e.g. bullsnake) with a soft leathery shell for the development of the young. Rattlesnakes are ovoviviparous, giving birth to living young (not from eggs); the fertile eggs develop within the female's body. The young develop coiled in a fetal sac - within a thin membranous wrap - in the female's oviduct area. A female rattlesnake will give birth to an average of 8-12 young (up to 24+) in August or September. The baby rattlers are normally 10 inches in length at birth. In the cooler northern climates, a female rattlesnake gives birth to young only every other year, not annually in South Dakota. The female rattlesnakes exhibit very little maternal care or protection for their young. Some mothers stay close to their young for a few days, mainly due to the exhaustion of giving birth. The young are on their own to find food and protective cover. Like other wild animals, many of the young do not survive beyond their first year of life.

Some simple precautions should be followed when in snake country:

All rattlesnakes are venomous, even young snakes. Studies have shown the venom of a young Prairie Rattlesnake may be up to three times the strength of the adult snake. In the United States, 12-15 people die annually from the bites of various venomous snakes.

Do not disturb, attempt to handle, or kill any venomous snake. One-third of the people bitten by snakes were trying to catch, handle or kill the snake. If you have a choice, leave the snake alone. Any sudden or quick movements may scare the snake and it may strike. Don't bother the snake and it won't bother you!!!! You have a greater chance of being struck by lightening than being bit by a venomous snake. One percent of all people have a chance of being bitten by a venomous snake and of the people bitten, only One percent will die. Under no circumstances should rattlesnakes be considered as pets. Even with professional snake handlers suffer bites. Any snakebite can be a serious situation and a medical nightmare!!!!

What should be done if you or another person is bitten? Determine whether the snake is still in the vicinity. Was it a venomous snake? DON'T waste precious time looking for the snake. Remember that any snake can and will bite, but in South Dakota the only native venomous snake is the Prairie Rattlesnake. These snakes are normally found west of the Missouri River (in central SD) and the counties bordering this river on its east side.

To identify a snake, look at the snakes tail and see if the tail is pointed or if the end portion has a rattle segment(s). Some rattlesnakes may have only a stub of the tail. These snakes may have lost the last portion of their tail into the skin section including the rattles. The tail may have been cut off by some farm machinery or bit off by another animal. Rattlesnakes do not regenerate their tails like lizards, but will have only a blunt stub of a tail with no rattles. Other venomous snakes such as copperheads, cottonmouths, and coral snakes have pointed tails, but these snakes are found across the southern US.

Extreme care should be used when confronting any snake. Capturing a live venomous snake should only be done by an experienced person using a snake tongs or a similar holding device. Commercially made snake tongs are in lengths of 26-50 inches and can be purchased from:

  • Pillstrom Tongs Company
  • 903 S. 10th St.
  • Rogers, Arkansas 72756-5211
  • by phone at: 479-452-3001

If someone is bitten by a venomous snake, try to remain calm, treat for shock, and seek medical attention immediately. Reduce physical activity and exertion as much as practical. Excitement and shock allow the hemotoxic venom of a rattlesnake to spread faster through the circulatory/lymphatic systems of the victims body. Time is critical with any snakebite, the victim should seek medical help as soon as possible. A person will normally know how serious the bite will be within the first 30 minutes. The location of the bite and the amount of venom injected are the main factors affecting the seriousness of the bite. In most cases, the bite area will swell up, turn black and blue and can be very painful. Any cutting or suction with the mouth or mechanical device in the bite area IS NOT RECCOMENDED and can be more dangerous than the snakebite itself. Remove any tight-fitting garments and constricting jewelry, such as rings.

The use of a compression type or wide elastic bandages (ACE) for snakebite first aid will delay and safely impede the spread of venom in the subcutaneous tissue. Experts advise that such wraps should be placed 1-2 inches above the bite - between the bite and the heart, wrapped as tight as for strains or sprained ankles, etc. (in Medical Herpetology by Steve Grenard - 1994)

Antivenin is a commercially made snake venom serum used to treat snakebite and is made from injections of specific snake venom into horses. The blood of horses later builds up immunity or forms antibodies against snake venom. Many people may have a dangerous allergic reaction to the antivenin once injected, because of the serum base of horse blood. The body's reaction to antivenin can be dramatic, and only trained medical staff should initiate injection of antivenin and where complete emergency care is available. Wyeth Laboratories in Philadelphia, PA (USA) produces such an antivenin kit for snakebite.

The best advice of what you will need for snakebite is a set of keys and a vehicle for transportation to a medical facility. The use of ice, stun guns, or tourniquets for snakebite ARE NOT recommended. Do not take any pills containing aspirin or ibuprofen and don't drink any alcohol, since these will thin the blood and may cause further complications. Advanced notice to the hospital or clinic, would also be helpful for their preparation for the incoming patient.

Most health-care professionals recommend just a few basic first-aid techniques for any snakebite. According to the American Red Cross, the following steps should be taken:

Snakes lead the list of the most misunderstood and feared of all animals in the world. Although it is important to realize the potential danger of some species, there is no need to fear or hate these reptiles. Leave them alone and they will likely do the same for you. Many animal species are facing extinction because of man's persistent use of pesticides and destruction of large areas of required habitat. Snakes are beneficial to people, but people are seldom beneficial to snakes!!!

Unfortunately, most people will kill any snake they come across, whether it is venomous or not - simply out of ignorance. In South Dakota, the rattlesnake is the only snake that is dangerous to man or beast. Snakes play an important environmental role in the food chain, eating a variety of prey, including worms, insects, gophers, mice, birds, frogs, salamanders, and other reptiles. Many of these snakes are some of Mother Nature's most efficient predators. Most snakes are harmless and try to avoid human contact. If we would take more time to observe and study all creatures, we would more readily accept the role of the many animals in our environment.