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Home/Species/ Western Diamond-backed Rattlesnake

Crotalus atrox

Baird and Girard, 1853

Western Diamond-backed Rattlesnake

G5Secure Found in 55 roadless areas NatureServe Explorer →
G5SecureGlobal Rank
Least concernIUCN
MediumThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.101695
Element CodeARADE02020
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVertebrate Animal
IUCNLeast concern
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomAnimalia
PhylumCraniata
ClassReptilia
OrderSquamata
FamilyViperidae
GenusCrotalus
Other Common Names
western diamondback rattlesnake (EN) Western Diamondback Rattlesnake (EN)
Concept Reference
Pyron, R. A., F. T. Burbrink, and J. J. Wiens. 2013. A phylogeny and revised classification of Squamata, including 4161 species of lizards and snakes. BMC Evolutionary Biology 29:131.
Taxonomic Comments
The traditional view of rattlesnake taxonomy that recognizes the two monophyletic sister genera Crotalus and Sistrurus (e.g. Brattstrom 1964) has recently been challenged. Stille (1987) and McCranie (1988) presented data that suggested Sistrurus is not monophyletic and rendered Crotalus paraphyletic. Parkinson (1999) found Sistrurus monophyletic but its position rendered Crotalus paraphyletic. Knight et al. (1993) used mtDNA to defend the traditional generic taxonomy, but in order to do so ignored the most parsimonious tree. The genus Crotalus is monophyletic when including the Mexican C. ravus (Murphy et al. 2002), and is supported as such in most recent phylogenies, as well as being the sister taxon to a monophyletic Sistrurus (e.g., Pyron et al. 2013) (Crother 2017).
Conservation Status
Review Date2006-08-28
Change Date1996-10-31
Edition Date2006-08-28
Edition AuthorsHammerson, G.
Threat ImpactMedium
Range Extent200,000-2,500,000 square km (about 80,000-1,000,000 square miles)
Number of Occurrences81 to >300
Range Extent Comments
The geographic range extends from southeastern California, possibly southern Nevada, central and southern Arizona, New Mexico, Texas, Oklahoma, and Arkansas south in Mexico to extreme northeastern Baja California, northern Sinaloa, Veracruz, and (at least formerly) disjunctly to Oaxaca (Ernst 1992, Campbell and Lamar 2004). It is unclear whether specimens collected in Kansas represent translocated individuals or part of a natural population (Matlack and Rehmeier 2002). Elevational range extends from near sea level to at least 2,440 meters in San Luis Potosi (Klauber 1972), but most locations are below 1,500 meters (Campbell and Lamar 2004).
Occurrences Comments
This species is represented by a large number of occurrences. Campbell and Lamar (2004) mapped hundreds of collection sites.
Threat Impact Comments
No major threats are known. Some populations have been decimated by habitat destruction, automobile traffic, and/or direct killing by humans, especially in conjunction with "rattlesnake roundups."
Ecology & Habitat

Habitat

Habitat encompasses arid and semiarid regions, from plains to mountains and from sandy flats to rocky uplands, including desert, grassland, shrubland, woodland, open pine forest, river bottoms, and coastal islands (Degenhardt et al. 1996, Tennant 1998, Werler and Dixon 2000, Stebbins 2003, Campbell and Lamar 2004). In southeastern Arizona, this snake is more numerous in desert scrub than in semidesert grassland (Mendelson and Jennings 1992). It hibernates in rock crevices or cavities or sometimes in animal burrows or under other cover (Ernst 1992). Hibernation sometimes occurs communally in brushy upland ridges. A population in southeastern Arizona used mainly creosotebush flats but switched to rocky slopes during winter (Beck 1995). This primarily terrestrial snake sometimes climbs into vegetation or enters water.

Ecology

May congregate at winter dens; at least formerly, dens served up to 100-200 individuals.

Movements tend to be greatest in spring, less in summer and fall (e.g., around 45-60 m per day), and least in winter (Landreth 1973). In southeastern Arizona, mean home range size was 5.42 ha and individuals moved an average of 51 m per day during the active season (Beck 1995).

In Oklahoma, slightly more than half of the snakes collected in rattlesnake roundups in April were second-year young and young adults thought to be 3-4 years old; annual adult mortality was estimated at 20% (Fitch and Pisani 1993).

Young are vulnerable to various carnivorous animals; humans are the only significant predators on adults.

Reproduction

In Oklahoma, births occur evidently in August and early September, sexual maturity is attained apparently in third year, breeding apparently is annual, fecundity (4-24 yolked follicles, mean 13) increases with female size, and the largest and oldest snakes probably are 10-15 years old (based on snakes examined at several rattlesnake roundups in Oklahoma, Fitch and Pisani 1993).

In south-central Arizona, mating occurred in spring and fall; females underwent vitellogenesis exclusively in spring, ovulated in early summer, and gave birth in August; over four years, no females gave birth more than once, indicating that reproduction is less than annual; litter sizes ranged from 2-7 (mean = 4.5) (Taylor and DeNardo 2005).
Terrestrial Habitats
Woodland - HardwoodWoodland - ConiferWoodland - MixedShrubland/chaparralSavannaGrassland/herbaceousDesertSand/duneBare rock/talus/screeCliff
Palustrine Habitats
Riparian
Other Nations (1)
United StatesN5
ProvinceRankNative
New MexicoS5Yes
ArizonaS5Yes
NevadaS4Yes
ArkansasS2Yes
TexasS4Yes
CaliforniaSNRYes
OklahomaS4Yes
Roadless Areas (55)
Arizona (32)
AreaForestAcres
Ash CreekPrescott National Forest7,663
Black CanyonPrescott National Forest10,683
Black CrossTonto National Forest5,966
BoulderTonto National Forest40,359
Butterfly Roadless AreaCoronado National Forest42,296
Catalina St. Pk. Roadless AreaCoronado National Forest951
Cdo WsaCoronado National Forest1,955
ChiricahuaCoronado National Forest76,876
Cimarron HillsCoconino National Forest5,303
GaliuroCoronado National Forest28,333
GoldfieldTonto National Forest15,257
Grief HillPrescott National Forest12,535
HackberryPrescott National Forest914
HackberryCoconino National Forest17,885
Happy ValleyCoronado National Forest7,972
Hell HoleApache-Sitgreaves National Forests15,512
Horse MesaTonto National Forest9,146
Lime CreekTonto National Forest42,568
Lower RinconCoronado National Forest3,278
Lower Romero WSRCoronado National Forest10
MazatzalTonto National Forest16,942
Middle Dragoon RoadlessCoronado National Forest10,543
Middle Romero WSRCoronado National Forest60
Oracle RoadlessCoronado National Forest22,365
PicachoTonto National Forest4,969
PinalenoCoronado National Forest130,920
Pine Mountain Wilderness ContiguousTonto National Forest6,518
Santa TeresaCoronado National Forest8,929
TumacacoriCoronado National Forest44,594
Upper Dragoon RoadlessCoronado National Forest2,533
Upper Romero WsrCoronado National Forest150
WhetstoneCoronado National Forest20,728
Idaho (1)
AreaForestAcres
Bear CreekCaribou-Targhee National Forest118,582
New Mexico (20)
AreaForestAcres
Alamo CanyonSanta Fe National Forest8,639
Apache Kid ContiguousCibola National Forest67,542
CajaSanta Fe National Forest5,304
Candian RiverCibola National Forest7,149
Carrizo MountainLincoln National Forest17,280
Contiguous To Black & Aldo Leopold WildernessGila National Forest111,883
Goat SpringCibola National Forest5,755
GrapevineLincoln National Forest2,086
Guaje CanyonSanta Fe National Forest6,104
Last Chance CanyonLincoln National Forest8,934
Little Dog And Pup CanyonsLincoln National Forest25,412
Ortega PeakLincoln National Forest11,545
Peloncillo (NM)Coronado National Forest43,339
RendijaSanta Fe National Forest2,176
Ryan HillCibola National Forest34,201
San JoseCibola National Forest16,950
Scott MesaCibola National Forest39,515
South Guadalupe MountainsLincoln National Forest20,930
Virgin CanyonSanta Fe National Forest6,068
West Face Sacramento MountainsLincoln National Forest41,176
South Dakota (1)
AreaForestAcres
Indian CreekBuffalo Gap National Grassland24,666
Texas (1)
AreaForestAcres
Big CreekNational Forests in Texas1,447
References (36)
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