Largely due to the risk and danger of snake bites, rattlesnakes have come to instill paranoia and fear in humans. As a result, there are numerous forms of rattler control, such as bounties, poisons, traps, and the destruction of food supplies and refuges. However, Crotalus atrox is a highly successful and fertile species, and therefore are not currently threatened by any forms of mass destruction or species control.
IUCN Red List of Threatened Species: least concern
The Western Diamondback Rattlesnake is notorious for its fatal bite, and has instilled a certain fear and paranoia in humans.
Crotalus atrox is good at controlling rodent problems. It also keeps well in captivity; this makes it a good educational resource in zoos and snake shows. Rattlesnakes are key in Native American culture, in which their flesh, oil, and venom have been used as a food source and as a basis for medicinal preparations for a long time. Rattlesnake skins are regularly used for skin products such as shoes and belts. Rattlesnakes are also prominent on the live-snake market, where they sell for $2 to $3 per foot (Klauber 158).
Crotalus atrox preys on small mammals and birds, and sometimes other reptiles and amphibians, and even fish and invertebrates. In a matter of seconds, individuals of this species can leave a fatal bite by injecting venom into its prey. The teeth often remain inside the prey, but are replaced 2 to 4 times annually by reserve teeth. Muscles surrounding the venom glands control the amount of venom released, as well as the flow of venom to the fangs. Rattlesnakes swallow their prey whole, then digest as the food passes though the body. Rattlesnakes in the wild eat every 2 to 3 weeks on average. Annual water intake in rattlesnakes roughly equals body weight. In drier climates, where water availability is lower, moisture is assimilated from prey. More water is absorbed during shedding due to desiccation and evaporation.
Reproduction
Behavior
Habitat
Biomes: desert, scrubland
The Western Diamondback Rattlesnake ranges from central and western Texas, through southern New Mexico and Arizona, and into southern California. It also extends well into central Mexico.
Biogeographic Regions: nearctic (Native )
Western Diamondback Rattlesnakes inhabit dry, rocky, shrub-covered terrain where they can conceal themselves inside crevices in the rocks or in mouse holes.
Terrestrial Biomes: desert or dune ; savanna or grassland ; chaparral
Average lifespan
Sex: female
Status: captivity: 25.8 years.
Average lifespan
Status: captivity: 22.0 years.
Body length: ~1.5 meters Body weight: up to 6.7 kg. Crotalus atrox has a plump body, short tail, and a broad triangular head. Like all Pit Vipers, it has a pit organ, which is situated in an indentation of the upper jaw, between the nostril and eye. The pit is about 5 mm deep, with an outer and inner chamber separated by a thin membrane. The membrane senses very slight temperature differences between the snake's inner and ambient temperatures. The Western Diamond Rattlesnake also has the self-named rattle on the end of the tail. Each link of the rattle is the remnant of a molted skin; as the snake molts, the last scale loosens but does not fall off. As the snake ages, new rattles are formed with each molt, while old rattles simultaneously fall off. This species has long, tubular fangs, which are characteristic of venomous snakes.
Crotalus atrox can be a yellowish gray, pale blue, or pinkish ground color. The diamond shapes down its length are dark with pale white borders. The tail is white with jet-black rings. The head markings include a pale oblique band from nostril to upper labials, and a similar but narrower band behind the eye.
Crotalus atrox reaches sexual maturity at 3 years. Mating occurs in the spring following emergence from hibernation. Females are passive during courtship, while the male crawls in jerks on top of the female, all the while flicking his tongue. Vigorously jerking the hind portion of his body, he presses his tail beneath that of his partner, who in turn lifts her tail. Their cloacas make contact, and the male then inserts his hemipenis, which is deeply forked. Copulation lasts for hours, with several interspersed resting periods.
The gestation period lasts for 167 days. The birthing process may last for 3 to 5 hours and produce 10 to 20 young. This species is ovoviviparous; the young pierce their thin egg membranes immediately before birth and are born live. The young only stay with the mother for a couple of hours, for a day at the most. Then they scatter in search for food and potential winter refuge. The young population declines drastically after the first winter due to lack of food, freezing temperatures, and vulnerability to predators.
Average number of offspring: 14.
Average age at sexual or reproductive maturity (male)
Sex: male: 1095 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 1095 days.
The Western Diamondback is often known to be the king of Southwestern desert rattlers. The Western Diamondback is recognized by its dull color ranging from gray to brown, the line down it’s back of diamond-shaped marks, the distinctive black stripes running from eyes to jaw, and the black and white ringtails circling the tail before its rattle. The range of dull coloring of the Western Diamondback is used for camouflage and determined by habitat. Western Diamondbacks are found in a range of habitats in the desert including desert flatland and rocky hillsides. Diamondbacks live in community dens during late autumn and will hibernate through the winter.
As the Diamondback can reach up to seven feet long, it is understandable why there is such fear connected to this snake. It is poisonous similar to other pit vipers. The spade-shaped head of the snake comes with fangs and a strong venom system. An interesting fact about the Western Diamondback is that they also have reserve fangs to replace any that may become damaged or break off. Similar to other snake species, the Diamondback molts two to three times a year. With each molt, the Diamondback adds on a rattle which is the keratin remains of its dead skin.
Prey include small mammals (prairie dogs, mice, gophers, etc.) and sometimes birds. The Diamondback is prevalent to hunting at night and typically attacks its prey. After the snake has a meal, it will go several weeks without eating again. Although the Diamondback seems like a major predator, there are many animals in its habitat that will make a meal of the snake− eagles, hawks, roadrunners, coyote, and badger are all on the list.
Western diamond-backed rattlesnake
Southwestern USA and northern Mexico: from central Arkansas and southeastern California (USA) south to northern Sinaloa, Hidalgo, and nothern Veraruz (Mexico). Isolated populations occur in southern Veracruz and southeastern Oaxaca (McDiarmid et al., 1999).
Holotype: USNM 7761
Type-locality: "Indianola" [Indianola, Calhoun County, Texas, USA] (McDiarmid et al., 1999).
The western diamondback rattlesnake[3] or Texas diamond-back[4] (Crotalus atrox) is a rattlesnake species and member of the viper family, found in the southwestern United States and Mexico. Like all other rattlesnakes and all other vipers, it is venomous. It is likely responsible for the majority of snakebite fatalities in northern Mexico and the greatest number of snakebites in the U.S.[5] No subspecies are currently recognized.[3]
It lives in elevations from below sea level up to 6,500 feet (2,000 m). This species ranges throughout the Southwestern United States and northern half of Mexico. Currently, western diamondback rattlesnakes are not threatened or endangered.
Other common names for this species include western diamond-backed rattlesnake,[3] adobe snake, Arizona diamond rattlesnake, coon tail, desert diamond-back, desert diamond rattlesnake, fierce rattlesnake, spitting rattlesnake, buzz tail, Texan rattlesnake, Texas diamond-back, and Texas rattler.
Adults commonly grow to 120 cm (4 ft) in length. Specimens over 150 cm (5 ft) are infrequently encountered, while those over 180 cm (6 ft) are very rare, and the largest reported length considered to be reliable is 213 cm (7 ft).[6] Males become much larger than females, although this difference in size does not occur until after they have reached sexual maturity.[5] Rattlesnakes of this species considered medium-sized weigh up to 1.23 to 2.7 kg (3 to 6 lb), while very large specimens can reportedly weigh up to 6.7 kg (15 lb).[7][8][9] Overall, it is probably the second largest-bodied species of rattlesnake, behind only its close cousin the eastern diamondback rattlesnake, and is also the second largest of North American venomous snakes (the bushmasters, which attain probably similar weights and greater total length, occur up as far as Nicaragua).[10][11][12]
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 23-45 (mean, 36) dorsal body blotches that are dark gray-brown to brown in color.[13] 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, hence the name "diamondback rattlesnake". The tail has two to eight (usually four to six) black bands separated by ash white or pale gray interspaces; this led to the nickname of "coon tail", though other species (e.g., Mojave rattlesnake) have similarly banded tails. Its postocular stripe 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 scale down to the supralabial scales just below and behind the eye.[5] Its off-white belly is usually unmarked, its anal scale is undivided, and its dorsal scales are extremely keeled, often in rows of 25 to 27 near the midbody.
The wide range of this species overlaps, or is close to, that of many others. It may be confused with them, but differences exist. The Mojave rattlesnake (C. scutulatus), also has tail rings, but the black rings are narrow relative to the pale ones. The timber rattlesnake (C. horridus), has no tail rings. In the western rattlesnake (C. oreganus), the pale tail rings are the same color as the ground. The tail of the black-tailed rattlesnake (C. molossus), is a uniform black, or has indistinct tail rings. The Mexican west coast rattlesnake (C. basiliscus), also has a mostly dark tail with obscure or absent rings. The tiger rattlesnake, (C. tigris), has a relatively small head and large rattle along with a dorsal pattern consisting more of crossbands. The Middle American rattlesnake (C. simus), has a generally uniform gray tail without any rings, as well as a pair of distinctive paravertebral stripes running down the neck. Members of the genus Sistrurus lack tail rings and have enlarged head plates.[5]
It is found in the United States from central Arkansas to southeastern and Central 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).[2]
In the United States, it occurs in 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, southwestern Utah, 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.[5]
In Mexico, it occurs in Nuevo León, Coahuila, Chihuahua, Sonora, extreme northeastern Baja California, northern Sinaloa, northeastern Durango, Zacatecas, most of San Luis Potosí, northern Veracruz, Hidalgo, and Querétaro. Specimens have been collected in the mountains northwest of Tehuantepec, Oaxaca, on numerous occasions, but have not been reported there since the 1940s.[5]
This species has also been reported on a number of islands in the Gulf of California, including San Pedro Mártir, Santa María (Sinaloa), Tíburon and the Turner Islands.[5]The Tortuga Island diamond rattlesnake is also a subspecies.
Its habitats range from flat coastal plains to steep rocky canyons and hillsides; it is associated with many different vegetation types, including desert, sandy creosote areas, mesquite grassland, desert scrub, and pine-oak forests. It is common to see the western diamondback on rural blacktop roads in early evening, because of the heat retention of these surfaces, as ambient temperatures drops.
C. atrox is solitary except during the mating season. Usually inactive between late October and early March, these ectotherms occasionally may be seen basking in the sun on warm winter days. In the winter, they hibernate or brumate in caves or burrows, sometimes with many other species of snakes. Life expectancy is more than 20 years.
They are poor climbers. Natural predators include raptors such as hawks and eagles, roadrunners, wild hogs, and other snakes. When threatened, they usually coil and rattle to warn aggressors. They are one of the more defensive rattlesnake species in the US in the way that they stand their ground when confronted by a foe. If rattling does not work, then the snake will strike in defense.[14]
A comprehensive study by Beavers (1976) on the prey of C. atrox in Texas showed, by weight, 94.8% of their prey consisted of small mammals.[5] According to Pisani and Stephenson (1991), who conducted a study of the stomach contents of C. atrox in the fall and spring of Oklahoma, mammalian prey included prairie dogs (Cynomys ludovicianus), kangaroo rats (Dipodomys ordii), pocket gophers (Geomys bursarius and Cratogeomys castanops), voles (Microtus ochrogaster), woodrats (Neotoma floridana), pocket mice (Perognathus hispidus and P. flavescens), white-footed mice (Peromyscus leucopus and P. maniculatus), Old World rats and mice (Rattus norvegicus and Mus ssp.), harvest mice (Reithrodontomys megalotis), fox squirrels (Sciurus niger), cotton rats (Sigmodon hispidus), ground squirrels (Spermophilus spilosoma), rabbits (Sylvilagus floridanus), jackrabbits (Lepus californicus), and an unidentified mole species.[5] Klauber mentioned large specimens are capable of swallowing adult cottontail rabbits and even adult jackrabbits, although he figured the latter required confirmation.[6]
Birds, lizards, amphibians, fish, invertebrates,[15] and mice are also preyed upon, with lizards mostly being eaten by young snakes. Avian prey include mockingbirds (Mimidae), quail, a nearly full-grown Gambel's quail, a burrowing owl (Athene cunicularia),[6] a fledgling horned lark (Eremophila alpestris) a black-throated sparrow (Amphispiza bilineata), and an eastern meadowlark (Sturnella magna).[5] Lizard prey include a whiptail lizard (Cnemidophorus), spiny lizards (Sceloporus), a Texas banded gecko (Coleonyx brevis),[6] and a side-blotched lizard (Uta palmeri). One case reported by Vorhies (1948) involved a juvenile specimen that had attempted to eat a horned lizard (Phrynosoma solare), but died after the lizard's horns had punctured its esophagus, leaving the lizard stuck there.[5]
Hermann (1950) reported C. atrox also feeds on lubber grasshoppers (Brachystola magna). Klauber (1972) once found a single specimen in which the stomach contents included grasshoppers, beetles, and ants. However, mammal hairs and an iguanid lizard were also found in the same stomach, which made it more likely that the insects had first been eaten by the mammal or the lizard before they had been eaten by the snake.[6]
They hunt (or ambush prey) at night or in the early morning.
These snakes can go for up to two years without food in the wild. A 5+1⁄2-month starvation study showed 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 the snakes grew during the study, indicating while the snake's mass was shrinking, it was putting its resources into skeletal muscles and bone.[16]
A key participant in the food chain, it is an important predator of many small rodents, rabbits, and birds. In turn, it is preyed upon by a variety of larger mammals and birds, such as coyotes, foxes, hawks, and owls. Crotalus atrox can be active at any time of the day or night when conditions are favorable. It is primarily diurnal and crepuscular in spring and fall and becomes primarily nocturnal and crepuscular during the hot summer months.[17]
They are one of the few species of snakes that engage in scavenging behavior.[18]
Like most other American pit vipers, the venom contains proteolytic enzymes. Proteolytic venoms are concentrated secretions that destroy structural tissues and proteins via catabolism, which help in disabling prey. The venom of C. atrox is primarily hemotoxic, affecting mainly the blood vessels, blood cells and the heart. The venom contains hemorrhagic components called zinc metalloproteinases.[19][20] The venom also contains cytotoxins and myotoxins which destroy cells and muscles, adding to the damage to the cardiovascular system.[21] In addition to hemorrhage, venom metalloproteinases induce myonecrosis (skeletal muscle damage), which seems to be secondary to the ischemia that ensues in muscle tissue as a consequence of bleeding and reduced perfusion. Microvascular disruption by metalloproteinases also impairs skeletal muscle regeneration, being thereby responsible for fibrosis and permanent tissue loss.[22] General local effects include pain, heavy internal bleeding, severe swelling, severe muscle damage, bruising, blistering, and necrosis; systemic effects are variable and not specific, but may include headache, nausea, vomiting, abdominal pain, diarrhea, dizziness, and convulsions. Bleeding caused by hemorrhagins is a major clinical effect that can be fatal.[23]
This species has LD50 values of 2.72 mg/kg intravenous, 20 mg/kg intramuscular and 18.5 mg/kg subcutaneous, which is far less toxic than many other rattlesnakes.[24][25] However, because of its large venom glands and specialized fangs, the western diamondback rattlesnake can deliver a large amount of venom in a single bite. The average venom yield per bite is usually between 250 and 350 mg, with a maximum of 700–800 mg.[5][26] Severe envenomation is rare but possible, and can be lethal. Mortality rate of untreated bites is between 10 and 20%.[23]
Rattlesnakes, including C. atrox, are viviparous. Gestation lasts six or seven months, and broods average about a dozen young. However, the young stay with the mother for only a few hours before they set off on their own to hunt and find cover, so that the mortality rate is very high. Mating occurs in the fall, and the females give birth to as many as 25 young, which may be as long as 30 cm (12 in). The young are fully capable of delivering a venomous bite from the moment they are born.
This species is classified as Least Concern on the IUCN Red List (v3.1, 2001).[1] Species are listed as such due to their wide distribution or presumed large population, or because they are unlikely to be declining fast enough to qualify for listing in a more threatened category. The population trend was stable when assessed in 2007.[27]
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 food, skins and entertainment.
This Western diamondback rattlesnake may be the most common rattlesnake species found in homes and in direct conflict with human development in the American Southwest, in particularly in the rapidly expanding metro areas of Phoenix and Tucson.[28] Relocation of animals is seen as a sometimes controversial management solution.[29]
C. atrox, albino specimen
C. atrox, melanistic specimen
C. atrox
C. atrox
The western diamondback rattlesnake or Texas diamond-back (Crotalus atrox) is a rattlesnake species and member of the viper family, found in the southwestern United States and Mexico. Like all other rattlesnakes and all other vipers, it is venomous. It is likely responsible for the majority of snakebite fatalities in northern Mexico and the greatest number of snakebites in the U.S. No subspecies are currently recognized.
It lives in elevations from below sea level up to 6,500 feet (2,000 m). This species ranges throughout the Southwestern United States and northern half of Mexico. Currently, western diamondback rattlesnakes are not threatened or endangered.
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