Description: The Colorado Desert Sidewinder looks as if it has horns over its eyes and is sometimes called the horned rattlesnake. These horns are actually upturned scales, and are not truly horns. The body is typically a sandy tan, gray, or cream color and is patterned with dark blotches of brown or grey on the back and sides. There is a dark cheek-stripe on both sides of the head that starts at the eye and runs diagonally down and backwards above the mouthline. The tail often has a few to several rings. The end of the tail has a rattle on it. The bottom of the rattle is brown.

Habitat: Inhabits primarily areas of wind-blown sands, especially where sand hummocks are topped withvegetation. Also found in hardpan, open flats, rocky hillsides, and other desert areas, especially those grown with creosote bush, where the terrain is open, not obstructed by rocks or vegetation, allowing the broad sidewinding locomotion.

Range: The Colorado Desert sidewinder is found in Sonoran Desert areas, from central and eastern Riverside County, California to Pinal County, Arizona in the United States, and south to northwestern Sonora and northeastern Baja California states in Mexico. It is in areas from the Lower Colorado River Valley to the surrounding desert foothills, at elevations between 499–2,001 feet. Its range has also been described as the desert regions of southeastern California, southwestern Arizona, as well as the western panhandle region of the Sonoran Desert.

Found in these States: AZ | CA

Venom: These snakes are venomous, but possess a weaker venom than many other rattlesnakes. This, together with the smaller size of their venom glands, makes them less dangerous than their larger relatives. Regardless, any rattlesnake bite can be fatal and should be taken seriously and medical attention sought immediately.

Envenomation can cause pain, swelling, hemorrhagic bleb formation, and ecchymosis (i.e., bruising). Swelling, while not particularly severe, occasionally may involve entire limbs and the trunk. Envenomation's systemic symptoms include nausea, dizziness, chills, coagulopathy (blood disorders), and shock. There is an account of a man who had been bitten on the first joint of the index finger of the right hand, with only a single fang penetrating. Although the bite was described as no more painful than a pin prick, a doctor was seen within about 25 minutes, and 10 cm3 of antivenin were administered. Within 2.5 hours, his entire arm was swollen and the pain was severe, "as if the arm were soaked in a bucket of boiling oil."

Ovine-derived antivenom, CroFab, for North American pit viper envenomation, has been widely available since 2001. Consultation with a local expert or regional poison control center should be obtained before administering antivenom. The previous antivenin (ACP) is no longer manufactured.

Diet: Eats mainly lizards when young, and eats increasingly larger prey including small rodents when grown. An ambush hunter, it sits buried beneath the surface of loose sand with just the top of the head showing, near kangaroo rat warrens, and lizard or rodent trails, then strikes at and releases the prey. The snake then follows the trail of the envenomated animal and swallows it whole

Reproduction: Rattlesnakes are ovoviviparous. The mother keeps her fertilized eggs inside her body and gives birth to living young. Females probably start bearing young at three years of age and breed annually. Mating occurs in the spring. 2 to 18 young are born from July to September.

Status: Listed as Least Concern in view of its wide distribution, presumed large population, and because it is unlikely to be declining fast enough to qualify for listing in a more threatened category.

Taxonomy: