- Common names: prairie rattlesnake, western rattlesnake, plains rattlesnake, more.
is a venomous pitviper species
native to the western United States
, southwestern Canada
, and northern Mexico
. Two subspecies
are recognized, including the nominate subspecies described here.
This species commonly grows to more than 100 cm in length. The maximum recorded size is 151.5 cm (Klauber, 1937). In Montana
, specimens occasionally exceed 120 cm in length; Klauber (1972) mentioned that the species reaches its maximum size in this region.
Prairie rattlesnake, western rattlesnake, plains rattlesnake, black rattler, common rattlesnake, confluent rattlesnake, Great Basin rattlesnake, large prairie rattlesnake, Missouri rattlesnake, rattlesnake of the prairies, spotted rattlesnake.
Found in North America
over much of the Great Plains
, from southern Canada
south through the United States
to northern Mexico
. In Canada it occurs in Alberta
; in the USA in eastern Idaho
, North Dakota
, South Dakota
, New Mexico
, extreme eastern Arizona
; in Mexico in northern Coahuila
and northwestern Chihuahua
. Its vertical range from 100 m near the Rio Grande River
to over 2,775 m elevation in Wyoming.
Wright and Wright (1957) and Klauber (1997) both mention Utah as within the range of this species, including maps showing it confined to the extreme southeastern part of the state.
The type locality is described as "the Upper Missouri" (Valley, USA). An emendation was proposed by Smith and Taylor (1950) to "Gross, Boyd County, Nebraska."
This species is classified as Least Concern (LC) 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 it is unlikely to be declining fast enough to qualify for listing in a more threatened category. The population trend is stable. Year assessed: 2006.
|C. v. nuntius
||The United States from northeastern and north-central Arizona, from the New Mexican line to Cateract Creek, including the Little Colorado River basin, the southern section of the Apache Indian Reservation, the Hopi Reservation, and the Coconino Plateau from the southern rim of the Grand Canyon to U.S. Highway 66 in the south.
|C. v. viridis
||North American Great Plains from the Rocky Mountains to long. 96° W. and from southern Canada to extreme northern Mexico, including southwestern Saskatchewan, southeastern Alberta, Idaho in the Lemhi Valley, Montana east of the higher Rockies, southwestern North Dakota, west, central and extreme southeastern South Dakota, western Iowa, central and western Nebraska, Wyoming except for the Rockies, Colorado, central and western Kansas, Oklahoma, extreme southeastern Utah, northeastern Arizona, New Mexico, western and southwestern Texas, northeastern Sonora, northern Chihuahua, northern Coahuila. |
The taxonomic history of this species is convoluted. Previously, seven other C. viridis
subspecies were also recognized, including abyssus
. However, in 2001 Ashton and de Queiroz published a paper describing their analysis of the variation of mitochondrial DNA
across the range of this species. Their results agreed broadly with those obtained by Pook et al.
(2000). Two main clades
were identified, east and west of the Rocky Mountains
, which they argued were actually two different species: on the one hand C. viridis
, including the conventional subspecies viridis
, and on the other C. oreganus
, including all the other traditional subspecies of C. viridis
. The authors retained the names of the traditional subspecies, but emphasized the need for more work to be done on the systematics
of C. oreganus
- Ashton KG, de Queiroz A. 2001. Molecular systematics of the Western Rattlesnake, Crotalus viridis (Viperidae), with comments on the utility of the D-Loop in phylogenetic studies of snakes. Molecular Phylogenetics and Evolution 21(2):176-189.