April 6, 2009 © Thomas J. Kollenborn. All Rights Reserved.
Spring is here early this year. Reptiles, meaning most coldblooded animals, becom very active when temperatures soar. August and September are traditionally the most active months for rattlesnakes on the Sonoran Desert at elevations below 4,000 feet. In the spring reptiles come out of hibernation and begin their search for food. In late fall when temperatures drop below seventy-eight degrees reptiles begin to prepare for hibernation.
I have lived in the Sonoran Desert for the past sixty years and I have encountered hundreds of rattlesnakes. If the truth were known, most of us who walk or hike in the desert will pass by ten snakes for everyone we see. Under most conditions a rattlesnake is very difficult to spot unless it is disturbed and it moves. Rattlesnakes generally rattle before they move, but not always.
A rattlesnake can easily be identified by the triangular shape of its head and the rattle on its tail. A closer examination will reveal an elliptical shaped pupil in its eye. Believe me, I don’t usually get that close to look! This trait is common to poisonous snakes in the Sonoran Desert.
All rattlesnakes will have a pit organ near the nostril orifice. Rattlesnakes come in a variety of colors and patterns. Most rattlesnakes found in our area will have rings around their tails above the rattles. The color of these rings will alternate between black and white in various shades. The visibility of these rings will depend on the species. The Western Diamond Back rattler’s rings are very pronounced and stand out, where as the rings on an Arizona Black is not very visible because of the blending of the rings. Occasionally a rattlesnake will lose it rattlers; when this occurs, the difficulty of identification increases.
Rattlesnakes are ectothermic vertebrates (cold-blooded animals), meaning they lack an appropriate physiological mechanism for maintaining body temperature. All coldblooded animals are at the mercy of their environment. The air and ground temperatures will dramatically affects all reptiles in their environment. This condition directly affects their daily rhythm of activity in their habitat.
There are six species of rattlesnakes in our area. They include the Western Diamond Back (Crotalus atrox), Mohave (Crotalus scutulatus), Arizona Black (Crotalus vidiris), Black-Tailed (Crotalus molossos), Sidewinder (Crotalus cerastes), and the Tiger (Crotalus tigris). These animals have a very highly developed mechanism for injecting venom therefore making them very successful predators on the desert. A rattlesnake’s diet is composed of small rodents 82% to 85% of the time.
Reptiles, including rattlesnakes, like cool shady spots during the spring, summer and fall months. During the winter months rattlesnakes generally go underground and hibernate. They usually choose caves and old mine tunnels. Occasionally dens of rattlesnakes have been accidentally uncovered by construction equipment and hundreds of rattlesnakes are found at one time.
Rattlesnakes have been known to come out of hibernation if temperature warm up to 78 degrees Fahrenheit. The functioning temperature for a rattlesnake is 72 degrees to 78 degrees Fahrenheit and its effective temperature is 82 degrees to 96 degrees Fahrenheit. The effective temperature is the temperature at which the snake moves about and hunts for prey. Direct exposure to heat or sunlight will kill a rattlesnake in 10 to 15 minutes.
You might say rattlesnake season is twelve months a year in the lower Sonoran Desert if temperatures rise above 72 degrees Fahrenheit in the winter months. Rattlesnakes are most commonly sighted from the first of April until about the middle of October. These animals are primarily nocturnal and prefer the hours after sundown and before sunrise. Most victims bitten by rattlesnakes are generally bitten ½ hour before sundown and up to two hours after sundown. It is estimated 72% of all bites occur during this period.
There are some interesting facts about rattlesnakes. The oldest known rattlesnake in captivity was 30 years and 7 months. This snake was a Western Diamond Back (Crotalus atrox). The largest rattlesnake officially recorded was an Eastern Diamond Back (Crotalus adamatus) at 7 feet 4 inches. The largest Western Diamondback was measured live at 6 feet 8 inches. There have been many wild claims about ten to fifteen-foot rattlesnakes, but usually these are snakes that were measured after death and their skin had been stretched. The average distance a rattlesnake can strike and effectively inject venom is approximately onethird of its body length.
Some eighty per cent of all rattlesnake bites are the results of carelessness or the handling of rattlesnakes by older juveniles or young adults. It is now estimated some 20% of rattlesnake bites are accidental or legitimate. About 15% of rattlesnake bites are dry socket-bites, meaning no venom was injected into the victim. The Arizona Poison Control Center and other medical resources reported some one hundred and twenty- one Crotalus envenomizations for the year 1991. This statistics quadrupled in 2003. Again statistics have almost quadrupled for 2005. These numbers continue to increase each year as our population continues to grow and more people head for the outdoors.
How do you know a rattlesnake has actually bitten you and if the reptile injected venom? There are several signs and symptoms of envenomization. First there will be fang marks. These fang marks can be singular, dual or even a scratch.
Fang marks are generally a very small puncture wound. A burning sensation usually follows the injection of venom by the reptile. A metallic or rubbery taste in the mouth often follows a bite, but not always. The tingling of the tongue or numbness can also occur. If a rattlesnake has injected venom into its victim, local swelling will occur within ten minutes. The amount of venom injected is generally indicated by the severity of edema or swelling at fang puncture site. Nausea and weakness is often associated with snakebite. Black or blue discoloration will generally appear near the site of the puncture wounds caused by the snake’s fangs after three to six hours. Every snake bite victim should be treated for shock. Shock is a greater threat to the victim’s survival then the actual venom of the snake.
The following is the recommended first aid for a rattlesnake bite. Call 911 immediately, snakebite is a medical emergency. If medical help is several hours away the following treatment is recommended. Calm and reassure the victim, decrease the movement of the limb. Identify the snake if it is possible without further risk of another bite. It is not recommended to use a constricting band or tourniquet unless you are a medical professional. Many snakebite victims have come into emergency rooms with a constricting band, such as shoelace, completely obliterated by edema or swelling. It is extremely important to move the victim to a medical facility without delay.
The following are some things we can do to prevent rattlesnake bite. When walking in the desert or in any area known for reptile habitation, always look where you step, or place your foot, or feet (caution should always be used at night, late evening, and early morning). Always look where you are placing your hands or fingers. Use extreme caution before placing your hands where you can not see what you are touching.
Always look before sitting down, especially around or near boulders or brush. Think before defecating or urinating in the outdoors. I have observed a variety of bites during the past fifty years that resulted from total lack of common sense. Small children must be closely supervised at all times in areas of possible snake infestation or inhabitation.
If you and your family observe these basic rules you should be safe from snakebite. Again, watch where you put your hands, feet and where you sit. As urbanization continues at the desert edge in Arizona the threat if snakebite is always a reality. Small children have become the tragic victims of snakebite in recent years because of little or no supervision.
I have tried to be as thorough as I can with accurate information about rattlesnakes in Arizona. It is important to take note, the better understanding we have of reptiles, the better chance we have of not becoming a victim of snakebite.
I would like to thank Jude McNally, and his staff, Arizona Poison Control Center, University of Arizona, Tucson, Arizona, and Dr. Findlay E. Russell and his enormously valuable resource Snake Venom Poisoning printed by Scholium International, Inc., Great Neck, New York 11021. This book is a physician’s desk reference for snake venom poisoning.
For information call Arizona Poison Control System 1-800-362-0101. (The state legislature may not be funding the Arizona Poison Control Center because of budget cuts this year.) For snake removal in Apache Junction call Apache Junction Fire District at 982-4440.