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Crotalus molossus

Crotalus molossus

Least Concern (IUCN)

Scientific classification

Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Squamata
Suborder:	Serpentes
Family:	Viperidae
Subfamily:	Crotalinae
Genus:	Crotalus
Species:	C. molossus

Binomial name

Crotalus molossus
Baird & Girard, 1853

Synonyms

Crotalus molossus - Baird & Girard, 1853
Crotalus ornatus - Hallowell, 1854
Caudisona molossus - Cope, 1860
C[audisona]. molossa - Cope, 1867
[Crotalus durissus] Var. molossus - Garman, 1884
Crotalus terrificus - Boulenger, 1986
Crotalus molossus molossus - Gloyd, 1936^[1]

Common names: black-tailed rattlesnake, green rattler,^[2] Northern black-tailed rattlesnake,^[3] more.

Crotalus molossus is a venomous pitviper species found in the southwestern United States and Mexico. Four subspecies are currently recognized, including the nominate subspecies described here.^[4]

Additional recommended knowledge

Daily Visual Balance Check

Correct Test Weight Handling Guide: 12 Practical Tips

Description

This is a medium-sized species^[2] that averages 76-107 cm in length.^[5] Large specimens are usually not much more than 100 cm, although lengths of 125.0 cm (Gloyd, 1940), 125.7 cm (Klauber, 1972) and 129.5 cm (Shaw & Campbell, 1974) have been reported.^[2] The females tend to be larger than the males.

They range in color from olive greens, to yellows, to browns, all the way to black. As their name implies, one of their most distinguishing features is that despite variations capable in body color, the tail scales are entirely black. Often these rattlesnakes have a black band that goes across their eyes and diagonally down to the corners of their mouth forming a sort of facial 'mask'.

Like other rattlesnakes, C. molossus has a rattle composed of keratin on the end of the tail. Each time the snake sheds its skin, a new segment is added to the rattle. They can shed their skin several times a year, and the rattle is fairly fragile and can be broken, so the length of a rattlesnake's rattle is not an accurate measure of its age.

Common names

Black-tailed rattlesnake, green rattler,^[2] northern black-tailed rattlesnake, dog-faced rattlesnake, dog-headed rattlesnake, mountain diamondback.^[3]

Geographic range

Found in the southwestern United States in Arizona, New Mexico and west and central Texas, and Mexico as far south as Oaxaca. Also found in the Gulf of California on San Estéban Island and Tiburón Island. The distribution reaches a maximum elevation of 2930 m. The type locality given is "Fort Webster, St. Rita del Cobre, N. Mex." (Fort Webster, Santa Rita del Cobre, Grant County, New Mexico, USA).^[1]

Conservation status

This species is classified as Least Concern (LC) on the IUCN Red List of Threatened Species (v3.1, 2001).^[6] 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: 2007.^[7]

Behavior

All rattlesnakes are carnivorous, their primary food sources being rodents, other small mammals, birds, and small reptiles. The behavior of Northern black-tailed rattlesnakes varies over the course of a year. In the spring and fall they are primarily diurnal. In the summer they shift to a nocturnal behavior, to avoid the heat of summer. In the winter, they hibernate in dens created and abandoned by other animals, often with other species of snake. They are variable in their form of locomotion depending on what substrate the need to traverse and will actively change between sidewinding or rectilinear movement. Although they are able climbers and expert swimmers, C. molossus is primarily a terrestrial species and inhabits grasslands, desert areas, rocky and mountainous areas, as well as higher altitude forested habitats.

Reproduction

Breeding occurs in the spring when males follow the pheromone trails of the females. Copulation can sometimes last for hours and happen multiple times over a period of days. After mating, the male often stays near the female for several days to prevent any other males from mating with her. The female gives birth to live young in the summer months, and the babies only stay with the mother only until they wander off on their own, usually less than a day or two. Females are believed to breed every year, and can have litters as large as 10-12 young, but usually averages 4-6. Their lifespan averages 15-20 years.

Subspecies

Subspecies^[4]	Authority^[4]	Common name	Geographic range
C. m. estebanensis	Klauber, 1949	San Esteban Island black-tailed rattlesnake	Mexico: Isla San Esteban (Gulf of California).
C. m. molossus	Baird & Girard, 1853	Northern black-tailed rattlesnake	United States (Arizona, New Mexico, southwest Texas), Mexico
C. m. nigrescens	Gloyd, 1936	Mexican black-tailed rattlesnake	Mexico (South Sonora, southwest Chihuahua, southern Coahuila, south to Oaxaca and Veracruz, Tlaxcala)
C. m. oaxacus	Gloyd, 1948	Oaxacan black-tailed rattlesnake	Mexico (Oaxaca)

References

^ ^a ^b 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).
^ ^a ^b ^c ^d 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.
^ ^a ^b Wright AH, Wright AA. 1957. Handbook of Snakes. Comstock Publishing Associates. (7th printing, 1985). 1105 pp. ISBN 0-8014-0463-0.
^ ^a ^b ^c Crotalus molossus (TSN 174314). Integrated Taxonomic Information System. Accessed on 24 February 2007.
^ Conant R. 1975. A Field Guide to Reptiles and Amphibians of Eastern and Central North America. Second Edition. First published in 1958. Houghton Mifflin Company Boston. 429 pp. 48 plates. ISBN 0-395-19979-4. ISBN 0-395-19979-8 (pbk.).
^ Crotalus molossus at the IUCN Red List. Accessed 13 September 2007.
^ 2001 Categories & Criteria (version 3.1) at the IUCN Red List. Accessed 13 September 2007.

Category: Crotalus

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Crotalus_molossus". A list of authors is available in Wikipedia.