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Western Diamondback Rattlesnake - Crotalus atrox

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The color pattern generally consists of a dusty looking gray-brown ground color, but it may also be pinkish brown, brick red, yellowish, pinkish or chalky white. This ground color is overlaid dorsally with a series of 24-25 dorsal body blotches that are dark gray-brown to brown in color. The first of these may be a pair of short stripes that extend backwards to eventually merge. Some of the first few blotches may be somewhat rectangular, but then become more hexagonal and eventually take on a distinctive diamond shape. The tail has 2-8 (usually 4-6) black bands separated by interspaces that are ash white or pale gray. There is a postocular stripe that is smoky gray or dark gray-brown and extends diagonally from the lower edge of the eye across the side of the head. This stripe is usually bordered below by a white stripe running from the upper preocular down to the supralabials just below and behind the eye.

Range & Habitat

Found in the United States from central Arkansas and southeastern California, south into Mexico as far as northern Sinaloa, Hidalgo and northern Veracruz. Disjunct populations exist in southern Veracruz and southeastern Oaxaca. The type locality given is "Indianola" (Indianola, Calhoun County, Texas, USA).

In the United States it occurs in the following states: central and western Arkansas, Oklahoma excluding the northeast, north-central region and the panhandle, Texas excluding the northern panhandle and the east, southern and central New Mexico and Arizona, extreme southern Nevada, and in southeastern California on either side of the Chocolate Mountains. Records from extreme southern Kansas (Cowley and Sumner Counties) may be based on a natural occurrence of the species, while multiple records from near Kanopolis Reservoir in Ellsworth County seem to indicate a viable (although isolated) population.

Behavior

Western diamondbacks can live for more than twenty years, but life expectancy is typically shorter because of hunting and human expansion. Solitary outside of mating season, they are one of the more aggressive species found in North America because they rarely back away from confrontation. When threatened they usually coil and shake their rattle to warn an aggressor that it has stumbled upon something dangerous. There is suspicion that some rattlesnakes (and the diamondback in particular) which generally live around populated areas do not rattle as often because it leads to the snake’s discovery and consequent destruction. However, there is little available evidence of this hypothesis.

C. atrox, like other desert snakes, can go for up to two years without food in the wild. A 5˝ month starvation study showed that the snakes reduced energy expenditures by an average of 80% over the length of the study. The snakes also feed from within on energy-rich lipid stores. The most interesting finding was that the snakes grew during the study, indicating that while the snake's mass was shrinking, it was putting its resources into skeletal muscles and bone.

In the winter, western diamondbacks hibernate in caves or burrows sometimes with many other species of snakes.

The snake is a poor climber and primarily hunts small mammals, but will also feed on birds, small reptiles and amphibians. They hunt (or ambush prey) at night or early morning using a type of infrared sense prominently found in pit vipers. Although adult specimens have no natural predators, hawks, eagles, and other snakes can prey on young or adolescent individuals.

The Venom

Although the venom of the diamondback isn't particularly toxic, the size of the snake allows a larger capacity of venom which is released from its two prominent fangs. It's not uncommon that only one bite mark from one fang is visible after a strike. Fangs can break or bend, or the bite area may be small, causing a miss. All pit vipers have the ability to control the flow of venom through their fangs, allowing the diamondback to release most of its venom in a single strike (though often a pit viper will not release any of its venom).

Most of the toxin released is proteolytic like all other American pit vipers. Proteolytic venoms are, in fact, advanced and concentrated fluids that destroy tissues and other cells through intramolecular digestion. A few toxic effects include: cytotoxic (destoys cells), hemotoxic (destroys red blood cells), myotoxic (causes paralysis and muscle destruction), hemorrhagic (causes persistent bleeding). Smaller amounts of neurotoxins are also present. Unlike neurotoxins, hemotoxin envenomations becomes quickly apparent; the area around the wound swells at a rapid rate. Discoloration and pain are also experienced shortly after being bitten. Professional medical attention should be sought immediately, especially when the victim is a child. The smaller the victim the less time it takes for the venom to spread. Although it is commonly believed that baby or young rattlesnakes deliver more concentrated venom and are thus more dangerous, this idea is not supported by scientific evidence. The amount of venom delivered is a much more important indicator of the bite's danger than the venom's concentration, and since larger (older) snakes can deliver much more venom, larger rattlesnakes should always be considered more dangerous even though many bites from adult snakes are "dry".

Additional Notes

In Captivity C. atrox is frequently bred in captivity, and readily available in the exotic animal trade. Many color variations are bred, including albinos, patternless, and melanistic. They are also heavily collected from the wild, frequently being drawn out of their hiding places with gasoline, and used in rattlesnake roundups where they are killed for entertainment.[2] Despite this, their population is not considered to be threatened.

Venomous or Harmless - The Look-a-Likes

HN_EDB.jpg Western Diamondback Rattlesnake
Venomous
HN_easternhog.jpg Western Hognose Snake
Harmless