The information conveyed by the informant emphasized these two spheres of information and also included cause-effect of rattlesnake bites, rationale of rattlesnakes biting humans, functions of rattlesnake sensory apparatus, spatial models of rattlesnake territories, ranges and habitats, and a sequence model for behavior if you hear a rattle or are bitten.
There are "seventeen different types of rattlesnakes" in Arizona. Direct elicitation revealed that "types" refers to the "eleven main species and six subspecies" so far known and recorded in Arizona. Rattlesnakes in Arizona belong to two genera of snakes. One species is a member of the genus Sisturus. "The smaller pygmy rattlers are in the Sisturus." The remainder are members of the genus Crotalus. Arizona has more types of rattlesnakes than in any other area in their range, with seventeen of the "thirty known species, including subspecies" of rattlesnakes.
The Types of Rattlesnakes
The Western Diamondback rattlesnake, Crotalus atrox, is the most common species. They are difficult to see; "they blend in very well." "Many years ago it wasn't too uncommon to find six-footers, but now with habitat destruction ... seeing anything over four feet is pretty rare." The Western Diamondback range is Arkansas to Southern California and south into Northern Mexico. They have ten rattles at about 5-6 years of age.
The most venomous rattlesnake in North America is the Mohave, Crotalus scutulatus," also called 'Three-Steppers' and 'Greenbacks.' Mohaves and Western Diamondbacks are "the two main snakes you are going to run across." "The Mohaves have a neurotoxic venom ... twenty times more toxic than the actual Western Diamondbacks." The Mohave "contributes to the most fatalities" in the Southwest. They are a "very secretive and non-aggressive rattlesnake" but a very deadly rattlesnakes, comparable to cobras. For every ten to fifteen Diamondbacks, one Mohave is found. It is distinguished by its very green color, an adaptation to sit on " the tops of Palo Verde trees, the tops of cactus ... waiting to ambush birds." While Mohaves are the second most common, the Arizona Blacktail or Blacktail Rattlesnake, Crotalus molossus, is the third most common rattlesnake in Arizona.
The Arizona Speckled Rattlesnake, Crotalus mitchelli, "has a very unique distinction ... of being the only blue-eyed snake in the entire Northern Hemisphere." Its coloration "ranges all the way from a snow white, all the way to a grey, all the way to royal blue in some areas, and in the red rock areas it will actually take on a red tint." Their head is small, and as a bat eater they are unique. They are "twice as venomous as a Western Diamondback" although "full grown at three feet" in length. They are most prevalent in mountains in the Gila Bend to Yuma area. They are an uncommon species.
Some rattlesnake species are very rare and have small ranges. The Banded Rock Rattlesnake, Crotalus lepidus is "a very obscure, protected species in the Chiricahua mountains." The Ridgenose Rattlesnake, Crotalus willardi, is a another very rare, protected species, also found in the Chiricahua Mountains in southern Arizona, as is Sisturus milarius, the Western Massasauga, "a pygmy rattler." Smaller pygmy rattlers are placed in the genus Sisturus. The Tiger Rattlesnake, Crotalus tigris, is also "very rare" and has distinct tiger-like stripes.
Two species have subspecies. The Prairie Rattlesnake, Crotalusviridis, is found in Eastern Arizona. The subspecies of the Prairie (also called the Western Rattlesnake) include the Grand Canyon Rattlesnake, Crotalus viridis abyssus, which is found in the Grand Canyon. The Hopi Rattlesnake, Crotalus viridis nuntius, is "mostly found ... in the Hopi reservation area." The Arizona Black, Crotalus viridis cerebus, "is a high mountain, high elevation rattlesnake," typically above 6,000 feet. "The black color ... is an adaptive, protective device to absorb as much heat as possible in those colder climates." The fourth subspecies of the Prairie Rattlesnake is the Great Basin Rattlesnake, Crotalus viridis lutosus. There are one species and two subspecies of Sidewinder Rattlesnakes, the Colorado Sidewinder, Crotalus cerastes, the Sonoran Sidewinder, Crotalus cerastes cercobombus, and the Desert sidewinder, Crotalus cerastes laterorepens.
Rattlesnakes in General
The "rattlesnake range" is "all the way from 53° latitude north in Southern Canada all the way down through the entire U. S., into Mexico, Central America, the Yucatan, into South America down to 35° latitude south." In the Arizona low desert "rattlesnake season" is the end of February and March. It is the "least opportune time to be bit. It is actually when they are fully venomized, coming out of their hibernaculums, ready to eat and they are very short-tempered."
Rattlesnakes are termed a "live-bearer, like a mammal." Most reptiles lay eggs. "They are the only snakes that we know of that express maternal instincts. They protect their young from several hours all the way to several weeks, until they do their first shedding." "Two to eleven babies are born every August." Baby rattlesnakes are very venomous. "They're very deadly, very, very dangerous right from the start." "Babies actually will eject all of their venom, as opposed to the adults that will eject some of their venom some of the time." Baby rattlesnakes do not have rattles; rattles develop after several skin sheddings. "Rattlesnakes don't necessarily rattle all the time." "They rattle when they feel threats." They also use their rattles for "intra-communication" called "caudaling." "It is like a Morse code." They slowly click to each other.
They "have pits between their eye and their nostril that is a sophisticated skin membrane that can actually pick up one degree variance in temperature up to twenty or thirty feet away." This sensory organ is "like a thousand dot" grid. "Even though they don't have an auditory device, an ear, what they do have is the ability, through their pits, to pick up sound." "They can hear someone walking towards them from up to 100 yards away without any problem." Their tongue is used as a sensory organ to "pick up air molecules." They can detect prey or predators by this means. Rattlesnakes use fangs to inject venom. The "hypodermic fangs on a rattlesnake work just like a hypodermic needle."
Hikers should not be hiking alone in rattlesnake country. "If you do hear a rattle, depending upon ... how far away it is ... the best advice is to be perfectly still." If "that snake is right on top of you, you need to be as perfectly still as long as you can." "Then if you have a stick with you ... put the stick between you and the snake." "Do not move at all, wait for it to calm down then slowly back up." "You never want to run." "Running in the desert is one of the last things you want to do." Where you find one snake there can be many more.
If bitten "the best advice is to be as immobile, as still, as you possibly can." "You do need to get to a hospital within two hours, that is the number one axiom today." A "loose, constricting band between the bite and the heart is very recommended." "Anti-venin is a must. It neutralizes the devastating effects of the venom." It "is a valid statistic" that eighty percent of those bitten are males between 20 and 50. "Many of those in that category are involved in alcohol consumption."
"The average person (that gets bit) is not from Arizona." "A lot of people who are bit are, unfortunately, from out of town." "Bites have increased to 400 a year reported bites as a result of habitat destruction, interaction with these animals through construction/development sites...." This is a significant increase due to "more people that are moving into snake territory." "There is a death about every 24 months to 36 months on the average." "Everyone that is bitten, that actually is venomized, has long-lasting consequences, including loss of motor dexterity, loss of tissue." Ninety percent of those bitten "are doing something that they should not have been doing to the snake in the first place." "Many of the people who are bit ... step right on them." "Ten percent are classified as legitimate bites."
According to the informant, people who are bitten by rattlesnakes have "a very hostile behavior towards these types of animals" and those who like snakes are bitten infrequently. The informant reports that in a controlled study snakes in an enclosure reacted defensively to ranchers who kill rattlesnakes and passively to zoologists who like them. "They usually, most of the time, know if they are in danger or not and they are pretty accurate about that. I believe they have tremendous perceptive telepathic powers." "They seem to know if you are out to help them or out to hurt them." "They will most definitely, most definitely retreat if they have a chance. They are not out to get humans."
Some Additional Terminology
"Hibernaculums" are communal dens where some rattlesnakes hibernate in the winter.
"Snake territory" is anywhere rattlesnakes live.
"Legitimate bites" are the ten percent of bites not caused by human provocation.
"Venomized" is to be injected with snake venom.
"Fatal statistic" is a person who dies from a rattlesnake bite.
"Dry bites" are when a snake bites but does not inject venom.
"Right on top of you" means within striking distance.
Analysis of the Data
A strict inclusion taxonomy of Arizona Rattlesnakes can be constructed according to two different schemas. Under the common name schema all rattlesnakes are in a single group. Table 1 presents the common name scheme, with the various common names for several of the types and also their scientific names. As such Table 1 also serves as a synonymy chart. Table 2 presents the scientific scheme of classification. In the scientific schema a single species of pygmy rattlesnake is in one genus while ten species are members of another genus together with six subspecies. The separation of pygmy rattlesnakes into a separate genus is based on size of the snakes. Five types of Prairie Rattlesnakes are grouped in one species, with Crotalus viridis viridis as the type species. Three types of Sidewinder Rattlesnakes are grouped in one species, with Crotalus cerastes as the type.
The attributes of rattlesnakes are used in both defining rattlesnakes as a group and in distinguishing types, species and subspecies of rattlesnakes. The taxonomy of rattlesnakes is dependent on understanding their attributes. Table 3 focuses on both their common and their contrasting attributes. Let us consider first the contrasting attributes. The species and subspecies distinction seemed most significant in the data gathered, and therefore is used herein as the first order distinction. Species and subspecies is also an exclusive model, with each rattlesnake being a separate entity with no overlap.
The contrasting data expresses various subsets of data, including the spatial relationships of the diverse species. Some species have distinct ranges. Several of the species share the low desert habitat and several rare species occur only in the Chiricahuas. Therefore characteristics other than range are needed to separate some of them. The spatial data is an integral aspect of species distinctions and the informant correlated species to range in almost every type. This is not surprising because speciation results from geographic separation and adaptations to diverse habitats and resources. Several other differentiating subsets of attributes were employed by the informant, including degree of venomy, size and ecology of ranges, population sizes (from most common to very rare and as proportions), physical size, distinct behaviors and color variations. All these subsets are parts of the complex set of diverse attributes used to distinguish the seventeen types of rattlesnakes. The data indicates that several attribute subsets are needed to distinguish rattlesnakes.
Only a few of the attributes serve both as common and contrasting attributes. Skin color as camouflage is a common attribute. Variations in color are contrasting attributes. Likewise venomy is a common attribute and degree of venomy is a contrasting attribute.
Of the common attributes that define a rattlesnake two subsets are immediately apparent, behaviors and body parts. Both body parts and behaviors both also have an important subset; their functions are relevant. The rattle is more than a rattle, and without some information of its function and the context of its use our understanding of rattlesnakes would be diminished. Rattlesnake sensory pits, fangs, tongue and skin colors likewise are best understood in relation to their functions. How a rattlesnake employs its attributes is an important aspect of the definition of a rattlesnake. Therefore rather than just list the body parts and venom their respective functions are included.
The data also presents several sequence relationships regarding human behavior. Both are the informant's recommendations regarding human behavior in relation to rattlesnakes, courses of action if one hears a rattle or if one is bitten. Each of these scenario relationships includes proscribed behavior to avoid unwanted outcomes. Rationale relationships were expressed for following the recommended scenario and not doing the proscribed behavior in both scenarios.
Usefulness of the Data
Knowing how many rattlesnakes exist, where snakes live, which is most venomous, what to do if bitten, and how to avoid bites can make the difference between life and very serious and long lasting injury or even death. My informant said that an "ounce of prevention" can spare a person a very expensive hospitalization.
It was difficult to perceive what questions to ask in the initial interview without some analysis time. A series of short interviews seems a recommendable method. In analyzing the data I discovered that the domain is far more complex than I had expected when I choose the topic. I previously had no idea of the total number of types of rattlesnakes in Arizona. I thought there were only a few.
Suggestions for Further Study
Several aspects of the domain were not fully explored or analyzed herein and represent areas for continuing study. These include the functions of rattlesnake attributes, the contrasting attributes of the rare species and more exactive delineation of ranges and ecological habitats. Details about the constituents and bioactivity of venom have not been explored. The informant provided far more information about the common species than about the rare species. The Chiricahua area species might offer a fertile area for exploration of the informant's understanding of the relationship of that area's unique sky islands ecology to speciation. Also, interviewing other experts in the same field would be useful in confirming which understandings are most universally held.
Attributes of Rattlesnakes. An outline of common and contrasting attributes.
A. Common attributes of rattlesnakes.
1. Rattlesnake behaviors.B. Contrasting attributes of rattlesnakes.a. Rattlesnakes are live-bearers that protect their young when born.2. Rattlesnake body parts.
1. Western Diamondback Rattlesnake.a. It is the most common rattlesnake in Arizona, by a factor of over ten.2. Mohave Rattlesnake.
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