Common names: southwestern speckled rattlesnake, Mitchell's rattlesnake, more.

Crotalus mitchellii pyrrhus is a venomous

Venomous snake

"Poisonous snake" redirects here. For true poisonous snakes, see Rhabdophis.Venomous snakes are snakes which have venom glands and specialized teeth for the injection of venom...

 pitviper

Crotalinae

The Crotalinae, commonly known as "pit vipers" or crotaline snakes, are a subfamily of venomous vipers found in Asia and the Americas. They are distinguished by the presence of a heat-sensing pit organ located between the eye and the nostril on either side of the head...

 subspecies

Subspecies

Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

 found in the southwestern United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 and northwestern Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

. A medium-sized snake, it is found mostly in rocky country, active at night and feeding on small mammals. The coloration is variable and depends on the color of the rocks and soil of the habitat.

Description

Adults grow to an average length of three feet (91 cm), but may sometimes exceed 4 feet (122 cm).

The color pattern is variable, depending on the color of the rocks and soil of the habitat. The ground color may be pink, brown, gray, yellow or nearly white, and speckled with black and white. The pattern (if present) may consist of rhombs, bands or blotches. The tail is ringed.

Common names

Southwestern speckled rattlesnake, bleached rattlesnake, Mitchell's rattlesnake, pale rattler, pallid rattlesnake, red rattlesnake, speckled rattlesnake, white rattlesnake.

Geographic range

Found in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 in southern California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

, southern Nevada

Nevada

Nevada is a state in the western, mountain west, and southwestern regions of the United States. With an area of and a population of about 2.7 million, it is the 7th-largest and 35th-most populous state. Over two-thirds of Nevada's people live in the Las Vegas metropolitan area, which contains its...

, southwestern Utah

Utah

Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...

 and western Arizona

Arizona

Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...

. Mexico in northwestern Sonora

Sonora

Sonora officially Estado Libre y Soberano de Sonora is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided into 72 municipalities; the capital city is Hermosillo....

 and northern Baja California

Baja California

Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...

. No type locality was included in Cope's original 1867 description. Coues In Wheeler (1875) lists it as "Cañon Prieto, a locality near Fort Whipple

Fort Whipple, Arizona

Fort Whipple was a U.S. Army post which served as Arizona Territory's capital prior to the founding of Prescott, Arizona. The post was founded by Edward Banker Willis in January 1864 in Chino Valley, Arizona, but was moved in May 1864 to Granite Creek near the present day location of Prescott. ...

 [Yavapai County

Yavapai County, Arizona

-2010:Whereas according to the 2010 U.S. Census Bureau:*89.3% White*0.6% Black*1.7% Native American*0.8% Asian*0.1% Native Hawaiian or Pacific Islander*2.5% Two or more races*5.0% Other races*13.6% Hispanic or Latino -2000:...

], Arizona."

Habitat

Rocky country, including rocky hillsides and canyons, talus slopes

Scree

Scree, also called talus, is a term given to an accumulation of broken rock fragments at the base of crags, mountain cliffs, or valley shoulders. Landforms associated with these materials are sometimes called scree slopes or talus piles...

 and rock ledges. In southern California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

, these snakes have sometimes been found in chaparral

Chaparral

Chaparral is a shrubland or heathland plant community found primarily in the U.S. state of California and in the northern portion of the Baja California peninsula, Mexico...

 or cactus country, but usually never stray far from the rocks that provide its usual shelter. Not exclusively a rock dweller, they have also been observed emerging from mammal burrows at dusk. The species has been found at elevations of more than 5,000 feet (1,524 m).

Behavior

Primarily nocturnal, these snakes shelter in rock crevices and mammal burrows during the heat of the day. They become more diurnal during the cooler months of the year.

Feeding

The diet consists mostly of small mammals, although birds and lizards are also taken, the latter especially by juveniles. There is one report of a large specimen that contained a nearly grown cottontail rabbit (Sylvilagus auduboni sanctidiegi). Another report describes a specimen that had eaten eight birds, most likely goldfinches, that had been attracted to a small fountain installed as a bird bath at a desert camp.

Reproduction

Ovoviviparous

Ovoviviparity

Ovoviviparity, ovovivipary, or ovivipary, is a mode of reproduction in animals in which embryos develop inside eggs that are retained within the mother's body until they are ready to hatch...

, with females giving birth to as many as 12 live young. Neonates are 12 inches (30 cm) long and prey mostly on lizards.

Venom

Hartnett (1931) describes a case of a man who was bitten on his left thumb. Aside from the sharp stab of the fangs being embedded, there was no pain until after an incision had been made and antivenin

Antivenin

Antivenom is a biological product used in the treatment of venomous bites or stings. Antivenom is created by milking venom from the desired snake, spider or insect. The venom is then diluted and injected into a horse, sheep or goat...

 had been administered. There was then severe pain that lasted for about an hour after the bite, followed eventually by much discoloration and swelling, his fingers looking like red bananas. His fingers and wrist were covered with bleb

Bleb (medicine)

In medicine, a bleb is a large blister filled with serous fluid. Blebs can form in a number of tissues due to different pathologies, including frostbitten tissues, and as a cause of spontaneous pneumothorax. In the lungs, a bleb is a collection of air within the layers of the visceral pleura...

s and his palm with one large blister

Blister

A blister is a small pocket of fluid within the upper layers of the skin, typically caused by forceful rubbing , burning, freezing, chemical exposure or infection. Most blisters are filled with a clear fluid called serum or plasma...

.

In another case, a man was bitten on his heel, through his overalls and a sock. At first, the sensation was like being stuck by a thorn, with only a drop of blood at fang mark. After 45 minutes and a 1¼ mile (2 km) walk, a tourniquet was applied and an incision made. Four hours later, his calf was considerably swollen and discolored, which was later followed by pain in the groin. Further symptoms were obscured by the treatment and an uneventful recovery was made.

External links

• C. m. pyrrhus at California Reptiles and Amphibians. Accessed 29 July 2008.
• C. m. pyrrhus at CalPhotos. Accessed 29 July 2008.