Twin spotted rattlesnake
Holotype: CAS-SU 1702 (formerly SU 1702) (McDiarmid et al., 1999).
Type-locality: "Huachuca Mts., (Cochise Co.) Arizona." (McDiarmid et al., 1999).
occurs (regularly, as a native taxon) in multiple nations
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: (20,000-2,500,000 square km (about 8000-1,000,000 square miles)) The range extends from southeastern Arizona (Chiricahua, Huachuca, Pinaleno, Dos Cabezas, and Santa Rita mountains) southward through the Sierra Madre Occidental to northeastern Sonora, western Chihuahua, and Durango), in the Sierra Madre Oriental of southeastern Coahuila, southern Nuevo Leon, southwestern Tamaulipas, and north-central San Luis Potosi), and in Aguascalientes (Prival et al. 2002, Campbell and Lamar 2004). Elevational range is about 4,000-10,500 feet (1,220-3,200 meters) (Stebbins 2003); lower limit is about 1,850 meters according to Campbell and Lamar 2004). Prival et al. (2002) found this species at 2,530-2,900 meters in the Chiricahua Mountains.
Distribution: USA (SE Arizona), Mexico (W Sonora, E Chihuahua, W Durango, SE Coahuila, S Nuevo Leon,SW Tamaulipas, Aguascalientes) miquihuanus: SE Nuevo Leon, SW Tamaulipas, SE Coahuila
Southeastern Arizona, USA and northern Mexico through the Sierra Madre occidental in Sonora, Chihuahua and Durango; in the Sierra Madre Oriental of southeastern Coahuila, Nuevo León, and Tamaulipas with isolated records in Aguascalientes and San Luis Potosí (McDiarmid et al., 1999).
Length: 66 cm
Catalog Number: USNM 46402
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Sex/Stage: Male; Juvenile
Year Collected: 1898
Locality: Miquihuana, Tamaulipas, Mexico
Elevation (m): 2591 to 2591
- Paratype: Gloyd, H. K. 1940. Special Publication Number Four. The Rattlesnakes, Genera Sistrurus and Crotalus: A Study in Zoogeography and Evolution. 102.
Sierra Madre Occidental Pine-oak Forests Habitat
This taxon is found in the Sierra Madre Occidental pine-oak forests ecoregion, which boasts some of the richest biodiversity anywhere in North America, and contains about two thirds of the standing timber in Mexico. Twenty-three different species of pine and about 200 species of oak reside within the Sierra Madre Occidental pine-oak forests ecoregion.
Pine-oak forests here typically grow on elevations between approximately 1500 and 3300 meters, and occur as isolated habitat islands in northern areas within the Chihuahuan Desert. Soils are typically deep, where the incline allows soil build-up and derived from igneous material, although metamorphic rocks also form part of the soils in the west and northwest portions of the sierra. Steep-sloped mountains have shaped some portions of the Sierra, while others are dominated by their deep valleys, tall canyons and cliffs. These steep-sided cliffs have thinner soils limiting vegetation to chaparral types; characterized by dense clumps of Mexican Manzanita (Arctostaphylos pungens), Quercus potosina and Netleaf Oak (Q. rugosa). There are also zones of natural pasture, with grasses from the genera Arisitida, Panicum, Bromus and Stevis.
The pine-oak forests gradually transform into an oak-grassland vegetative association. Such communities represent an ecological transition between pine-oak forests and desert grasslands.. Here, species such as Chihuahuan Oak (Quercus chihuahuensis), Shin Oak (Q. grisea), Q. striatula and Emory Oak (Q. emoryi), mark a transition zone between temperate and arid environments, growing in a sparse fashion and with a well-developed herbaceous stratum resembling xeric scrub. Cacti are also part of these transition communities extending well into the woodlands. Some cacti species such as the Little Nipple Cactus (Mammillaria heyderi macdougalii), Greenflower Nipple Cactus (M. viridiflora), Mojave Mound Cactus (Echinocereus triglochidiatus), and Leding's Hedgehog Cactus (E. fendleri var. ledingii) are chiefly centered in these biotic communities. The dominant vegetation in the northernmost part of the ecoregion in the Madrean Sky Islands includes Chihuahua Pine (Pinus leiophylla), Mexican Pinyon (P. cembroides), Arizona Pine (P. arizonica), Silverleaf Oak (Quercus hypoleucoides), Arizona White Oak (Q. arizonica), Emory Oak (Q. emoryi), Netleaf Oak (Q. rugosa), Alligator Juniper (Juniperus deppeana), and Mexican Manzanita (Arctostaphylos pungens).
This ecoregion is an important area for bird richness and bird endemism. Likewise, virtually all of the ecoregion is included in the Sierra Madre Occidental and trans-mexican range Endemic Bird Area. Endemic bird species include the Thick-billed Parrot (Rhynchopsitta pachyrhyncha EN) which is in danger of extinction, with population estimates as low as 500 pairs; the Tufted Jay (Cyanocorax dickeyi NT), Eared Quetzal (Euptilptis neoxenus NT) and the Green-striped Brush Finch (Buarremon virenticeps). Temperate and tropical influences converge in this ecoregion, forming a unique and rich complex of flora and fauna. Many other birds are found in this ecoregion including the Green Parakeet (Aratinga holochlora), Eared Trogon (Euptilotis neoxenus NT), Coppery-tailed Trogon (Trogon elegans), Grey-breasted Jay (Aphelocoma ultramarina), Violet-crowned Hummingbird (Amazilia violiceps), Spotted Owl (Strix occidentalis NT), and Golden Eagle (Aguila chryaetos). Some species found only in higher montane areas are the Gould's Wild Turkey (Meleagris gallopavo mexicana), Band-tailed Pigeon (Patagioenas fasciata), Mexican Chickadee (Poecile sclateri) and Hepatic Tanager (Piranga flava).
The Sierra Madre Mantled Ground Squirrel (Spermophilus madrensis NT) is an endemic to the Sierra Madre Occidental pine-oak forests, restricted to southwestern Chihuahua, Mexico. The Mexican Gray Wolf (Canis lupus baileyi) and Mexican Grizzly Bear (Ursus horribilis), although considered by most to be extinct from this ecoregion, once roamed these mountains. Mammals also present include White-tailed Deer (Odocoileus virginianus), American Black Bear (Ursus americanus), Buller’s Chipmunk (Tamias bulleri), endemic Zacatecan Deer Mouse (Peromyscus difficilis), rock Squirrel (Spernophilis variegatus), Zacatecas Harvest Mouse (Reithrodontomys zacatecae) and Coati (Nasua nasua), to set forth a subset of mammals present.
Reptiles are also numerous in this ecoregion. Fox´s Mountain Meadow Snake (Adelophis foxi) is an endemic taxon to the ecoregion, only observed at the type locality at four kilometers east of Mil Diez, about 3.2 kilometers west of El Salto, in southwestern Durango, Mexico. There are at least six species of rattlesnakes including the Mexican Dusky Rattlesnake (Crotalis triseriatus), Mojave Rattlesnake (C. scutulatus), Rock Rattlesnake (C. lepidus), Western Diamondback Rattlesnake (C. atrox), Twin-spotted Rattlesnake (C. pricei), and Ridgenose Rattlesnakes (C. willardi). Clark's Spiny Lizard (Sceloporus clarkii) and Yarrow's Spiny Lizard (S. jarrovii), Bunchgrass Lizard (S. scalaris), and Striped Plateau Lizard (S. virgatus) are several of the lizards found in the Sierra Madre Occidental pine-oak forests.
Along springs and streams the Western Barking Frog (Craugastor augusti) and the Tarahumara Frog (Rana tamahumarae) are two anuran taxa occurring in the ecoregion. Other anuran taxa found here include: Bigfoot Leopard Frog (Lithobates megapoda), Northwest Mexico Leopard Frog (Lithobates magnaocularis) and the Blunt-toed Chirping Frog (Eleutherodactylus modestus VU). The Sacramento Mountains Salamander (Aneides hardii) is an endemic salamander found in the Sierra Madre Occidental pine-oak forests, restricted to the Sacramento Mountains, Capitan Mountains, and Sierra Blanca in Lincoln and Otero Counties within southern New Mexico, USA.
- David E. Brown, ed. 1994. Biotic Communities: Southwestern United States and Northwestern Mexico. University of Utah Press, Salt Lake City, Utah. ISBN: 0874804590
- World Wildlife Fund & C. Michael Hogan. 2013."Sierra Madre Occidental pine-oak forests". Encyclopedia of Earth, National Council for Science and the Environment, Washington DC ed. Rodney L. Honeycutt.
Chihuahuan Desert Habitat
This taxon is found in the Chihuahuan Desert, which is one of the most biologically diverse arid regions on Earth. This ecoregion extends from within the United States south into Mexico. This desert is sheltered from the influence of other arid regions such as the Sonoran Desert by the large mountain ranges of the Sierra Madres. This isolation has allowed the evolution of many endemic species; most notable is the high number of endemic plants; in fact, there are a total of 653 vertebrate taxa recorded in the Chihuahuan Desert. Moreover, this ecoregion also sustains some of the last extant populations of Mexican Prairie Dog, wild American Bison and Pronghorn Antelope.
The dominant plant species throughout the Chihuahuan Desert is Creosote Bush (Larrea tridentata). Depending on diverse factors such as type of soil, altitude, and degree of slope, L. tridentata can occur in association with other species. More generally, an association between L. tridentata, American Tarbush (Flourensia cernua) and Viscid Acacia (Acacia neovernicosa) dominates the northernmost portion of the Chihuahuan Desert. The meridional portion is abundant in Yucca and Opuntia, and the southernmost portion is inhabited by Mexican Fire-barrel Cactus (Ferocactus pilosus) and Mojave Mound Cactus (Echinocereus polyacanthus). Herbaceous elements such as Gypsum Grama (Chondrosum ramosa), Blue Grama (Bouteloua gracilis) and Hairy Grama (Chondrosum hirsuta), among others, become dominant near the Sierra Madre Occidental. In western Coahuila State, Lecheguilla Agave (Agave lechuguilla), Honey Mesquite (Prosopis glandulosa), Purple Prickly-pear (Opuntia macrocentra) and Rainbow Cactus (Echinocereus pectinatus) are the dominant vascular plants.
Because of its recent origin, few warm-blooded vertebrates are restricted to the Chihuahuan Desert scrub. However, the Chihuahuan Desert supports a large number of wide-ranging mammals, such as the Pronghorn Antelope (Antilocapra americana), Robust Cottontail (Sylvilagus robustus EN); Mule Deer (Odocoileus hemionus), Grey Fox (Unocyon cineroargentinus), Jaguar (Panthera onca), Collared Peccary or Javelina (Pecari tajacu), Desert Cottontail (Sylvilagus auduboni), Black-tailed Jackrabbit (Lepus californicus), Kangaroo Rats (Dipodomys sp.), pocket mice (Perognathus spp.), Woodrats (Neotoma spp.) and Deer Mice (Peromyscus spp). With only 24 individuals recorded in the state of Chihuahua Antilocapra americana is one of the most highly endangered taxa that inhabits this desert. The ecoregion also contains a small wild population of the highly endangered American Bison (Bison bison) and scattered populations of the highly endangered Mexican Prairie Dog (Cynomys mexicanus), as well as the Black-tailed Prairie Dog (Cynomys ludovicianus).
The Chihuahuan Desert herpetofauna typifies this ecoregion.Several lizard species are centered in the Chihuahuan Desert, and include the Texas Horned Lizard (Phrynosoma cornutum); Texas Banded Gecko (Coleonyx brevis), often found under rocks in limestone foothills; Reticulate Gecko (C. reticulatus); Greater Earless Lizard (Cophosaurus texanus); several species of spiny lizards (Scelopoprus spp.); and the Western Marbled Whiptail (Cnemidophorus tigris marmoratus). Two other whiptails, the New Mexico Whiptail (C. neomexicanus) and the Common Checkered Whiptail (C. tesselatus) occur as all-female parthenogenic clone populations in select disturbed habitats.
Representative snakes include the Trans-Pecos Rat Snake (Bogertophis subocularis), Texas Blackhead Snake (Tantilla atriceps), and Sr (Masticophis taeniatus) and Neotropical Whipsnake (M. flagellum lineatus). Endemic turtles include the Bolsón Tortoise (Gopherus flavomarginatus), Coahuilan Box Turtle (Terrapene coahuila) and several species of softshell turtles. Some reptiles and amphibians restricted to the Madrean sky island habitats include the Ridgenose Rattlesnake (Crotalus willardi), Twin-spotted Rattlesnake (C. pricei), Northern Cat-eyed Snake (Leptodeira septentrionalis), Yarrow’s Spiny Lizard (Sceloporus jarrovii), and Canyon Spotted Whiptail (Cnemidophorus burti).
There are thirty anuran species occurring in the Chihuahuan Desert: Chiricahua Leopard Frog (Rana chircahuaensis); Red Spotted Toad (Anaxyrus punctatus); American Bullfrog (Lithobates catesbeianus); Canyon Treefrog (Hyla arenicolor); Northern Cricket Frog (Acris crepitans); Rio Grande Chirping Frog (Eleutherodactylus cystignathoides); Cliff Chirping Frog (Eleutherodactylus marnockii); Spotted Chirping Frog (Eleutherodactylus guttilatus); Tarahumara Barking Frog (Craugastor tarahumaraensis); Mexican Treefrog (Smilisca baudinii); Madrean Treefrog (Hyla eximia); Montezuma Leopard Frog (Lithobates montezumae); Brown's Leopard Frog (Lithobates brownorum); Yavapai Leopard Frog (Lithobates yavapaiensis); Western Barking Frog (Craugastor augusti); Mexican Cascade Frog (Lithobates pustulosus); Lowland Burrowing Frog (Smilisca fodiens); New Mexico Spadefoot (Spea multiplicata); Plains Spadefoot (Spea bombifrons); Pine Toad (Incilius occidentalis); Woodhouse's Toad (Anaxyrus woodhousii); Couch's Spadefoot Toad (Scaphiopus couchii); Plateau Toad (Anaxyrus compactilis); Texas Toad (Anaxyrus speciosus); Dwarf Toad (Incilius canaliferus); Great Plains Narrowmouth Toad (Gastrophryne olivacea); Great Plains Toad (Anaxyrus cognatus); Eastern Green Toad (Anaxyrus debilis); Gulf Coast Toad (Incilius valliceps); and Longfoot Chirping Toad (Eleutherodactylus longipes VU). The sole salamander occurring in the Chihuahuan Desert is the Tiger Salamander (Ambystoma tigrinum).
Common bird species include the Greater Roadrunner (Geococcyx californianus), Burrowing Owl (Athene cunicularia), Merlin (Falco columbarius), Red-tailed Hawk (Buteo jamaicensis), and the rare Zone-tailed Hawk (Buteo albonotatus). Geococcyx californianus), Curve-billed Thrasher (Toxostoma curvirostra), Scaled Quail (Callipepla squamata), Scott’s Oriole (Icterus parisorum), Black-throated Sparrow (Amphispiza bilineata), Phainopepla (Phainopepla nitens), Worthen’s Sparrow (Spizella wortheni), and Cactus Wren (Campylorhynchus brunneicapillus). In addition, numerous raptors inhabit the Chihuahuan Desert and include the Great Horned Owl (Bubo virginianus) and the Elf Owl (Micrathene whitneyi).
- C. Michael Hogan & World Wildlife Fund. 2013."Chihuahuan Desert". Encyclopedia of Earth, National Council for Science and the Environment, Washington DC ed.Mark McGinley.
- Clovis A. Stacey & Diane M. Post. 2009. Effects of disturbance by humans on small mammals in a Chihuahuan Desert ecosystem. The Southwestern Naturalist. 54(3): 272-278
Habitat and Ecology
Comments: This species is a mountain rock dweller of pine-oak woodland, grassy and brushy areas, and open coniferous forest, usually occurring on well-lit rocky slopes such as south-facing talus (Stebbins 2003, Campbell and Lamar 2004). In Mexico, it is also found in grassy/shrubby mountain valleys where prey is abundant, on pinyon-pine/agave slopes, and in limestone/scrub oak/agave habitats where pines have been reduced by logging (the latter two habitats pertain to the eastern subspecies miquihuanus, Armstrong and Murphy 1979). This snake was found among stumps and coarse woody debris in July in high-elevation pine-oak forest in Sierra del Nido, Chihuahua (Bryson et al. 2002). In autumn, individuals may shift from summer habitat to a diffferent winter habitat (e.g., a different talus slope or beneath surface cover in a nontalus site (Prival et al. 2003).
Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
In the Chiricahua Mountains, single-season home range size was small (averaged 2.3 ha for males, the more mobile sex), but one male used an area of 14.7 ha over 13 months, and his monsoon-season locations in one year did not overlap with those of the next year (Prival et al. 2002).
Comments: Preys on lizards, small mammals, and nestling birds (e.g., yellow-eyed junco, Gumbart and Sullivan 1990). Lizards dominated the diet in the Chiricahua Mountains (Prival et al. 2002).
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 21 - 80
Comments: This species is represented by many occurrences (subpopulations). On a range-wide scale, Campbell and Lamar (2004) mapped about 46 collection sites.
10,000 - 1,000,000 individuals
Comments: Adult population size is unknown but presumably exceeds 10,000. This snake is locally common in some areas but apparently rare in the southern part of the range.
In suitable habitat, several may occur in an area of a few square meters (Lowe et al. 1986).
Life History and Behavior
Comments: Inactive in cold temperatures and extreme heat. Active on sunny mornings and during warm rains (Stebbins 1985). Apparently adapted to relatively low ambient temperatures (Ernst 1992). Has been found near rocky retreats from March to November; frequently observed on warm humid days with diffuse sunlight (Armstrong and Murphy 1979). May change locations by at least 11 m even in winter (Prival et al. 2003).
Lifespan, longevity, and ageing
In the Chiricahua Mountains, mating was concentrated in August and early September; births occurred in late July and August; mean number of embryos was 4 (range 1-6); female reproduction appeared to be biennial or less frequent; females developed embryos at 4-5 years of age (Prival et al. 2002). Viviparous. Gives birth to 3-9 young, July-August (Lowe et al. 1986).
Molecular Biology and Genetics
Statistics of barcoding coverage: Crotalus pricei
Public Records: 0
Specimens with Barcodes: 4
Species With Barcodes: 1
IUCN Red List Assessment
Red List Category
Red List Criteria
National NatureServe Conservation Status
Rounded National Status Rank: N3 - Vulnerable
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
Global Short Term Trend: Relatively stable (=10% change)
Comments: Currently, extent of occurrence, area of occupancy, number of subpopulations, and population size probably are stable.
Global Long Term Trend: Increase of 10-25% to decline of 30%
Comments: Ernst and Ernst (2003) stated that this species is now less common in Arizona than it was prior to 1982, but no evidence supporting this statement was provided.
Degree of Threat: Low
Comments: No major threats are known; most localities in Mexico are remote and difficult to access. Potential threats in Arizona include mining, grazing, overcollecting, logging, and recreational or other development (Johnson and Mills, cited by Ernst 1992).
Relevance to Humans and Ecosystems
Comments: Venomous; has low venom yield but venom is relatively potent, so caution should be exercised when working with these snakes; evidently there have been no fatalities from human envenomation (Ernst 1992).
Adults usually do not exceed 50–60 cm (about 20-24 in) in length. The maximum length recorded is 66 cm (26 in).
The color pattern consists of a gray, bluish-gray, brownish-gray, or medium- to reddish-brown ground color, usually with a fine brown speckling. This is overlaid with a series of dorsal blotches that tend to be divided down the median line to form 39-64 pairs.
Its common names are twin-spotted rattlesnake, western twin-spotted rattlesnake, Price's rattlesnake, Arizona spotted rattlesnake, spotted rattlesnake, and Arizona twin-spotted rattlesnake.
This snake is found in the United States in southeastern Arizona. In northern Mexico, it occurs in the Sierra Madre Occidental in Sonora, Chihuahua, and Durango. It has also been found in the Sierra Madre Oriental in southeastern Coahuila, Nuevo León, and Tamaulipas, with isolated records in San Luis Potosí and Aguascalientes. The type locality given is "Huachua Mts., Arizona" (Cochise County, Arizona, USA).
This species is classified as Least Concern on the IUCN Red List of Threatened Species (v3.1, 2001). Species are listed as such due to their wide distribution, 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.
|Subspecies||Taxon author||Common name||Geographic range|
|C. p. miquihuanus||Gloyd, 1940||Eastern twin-spotted rattlesnake||Mexico: southeastern Coahuila, Nuevo León and Tamaulipas|
|C. p. pricei||Van Denburgh, 1895||Western twin-spotted rattlesnake||United States: southeastern Arizona, Mexico: Sonora, Chihuahua and Durango|
- List of crotaline species and subspecies
- Crotalus by common name
- Crotalus by taxonomic synonyms
- Crotalinae by common name
- Crotalinae by taxonomic synonyms
- McDiarmid RW, Campbell JA, Touré T. 1999. Snake Species of the World: A Taxonomic and Geographic Reference, vol. 1. Herpetologists' League. 511 pp. ISBN 1-893777-00-6 (series). ISBN 1-893777-01-4 (volume).
- Campbell JA, Lamar WW. 2004. The Venomous Reptiles of the Western Hemisphere. Comstock Publishing Associates, Ithaca and London. 870 pp. 1500 plates. ISBN 0-8014-4141-2.
- Klauber LM. 1997. Rattlesnakes: Their Habitats, Life Histories, and Influence on Mankind. Second Edition. First published in 1956, 1972. University of California Press, Berkeley. ISBN 0-520-21056-5.
- "Crotalus pricei". Integrated Taxonomic Information System. Retrieved 1 August 2007.
- Moll, Edward O. 2003. Patronyms of the Pioneer West, V. Crotalus pricei, Van Denburgh, 1895 – Twin-spotted rattlesnake. Sonoran Herpetologist 16(12):110-112.
- Wright AH, Wright AA. 1957. Handbook of Snakes of the United States and Canada. (7th printing, 1985). Comstock Publishing Associates. Ithaca and London. 1105 pp. ISBN 0-8014-0463-0.
- Brown JH. 1973. Toxicology and Pharmacology of Venoms from Poisonous Snakes. Springfield, Illinois: Charles C. Thomas. 184 pp. LCCCN 73-229. ISBN 0-398-02808-7.
- Crotalus pricei at the IUCN Red List. Accessed 13 September 2007.
- 2001 Categories & Criteria (version 3.1) at the IUCN Red List. Accessed 13 September 2007.
- Van Denburgh, J. 1895. Description of a new rattlesnake (Crotalus pricei) from Arizona. Proc. California Acad. Sci., Series 2, 5: 856-857.
Names and Taxonomy
Comments: Taxonomic status of the two subspecies (widely separated populations in the Sierra Madre Occidental and Sierra Madre Oriental) needs to be evaluated (Crother et al. 2000).