Arizona is home to a high concentration of venomous snakes, particularly rattlesnakes. These reptiles are pit vipers, distinguished by heat-sensing pits between the eye and nostril, and the segmented rattle at the end of the tail. Rattlesnakes are native only to the Americas, and the southwestern United States represents the northern limit of their highest diversity. Arizona’s diverse geography has allowed a remarkable number of these predators to evolve and thrive.
Arizona’s Biogeography and Rattlesnake Diversity
Arizona has the highest rattlesnake diversity in the United States, resulting from its complex biogeography. The state is a meeting point for major North American ecological regions, including the Sonoran Desert, the Mojave Desert, the Colorado Plateau, and the Rocky Mountains. This convergence creates a mosaic of distinct habitats, from low-elevation arid scrublands to high-altitude pine forests.
Elevation extremes are a major factor, ranging from near sea level to over 12,000 feet. This range dictates climate zones that promote isolation, allowing populations to evolve specific adaptations. Rattlesnake populations isolated in specific mountain ranges or desert basins can diverge genetically over time, leading to many distinct species and subspecies.
The Thirteen Rattlesnakes of Arizona: Identification and Distribution
Arizona is home to 13 commonly recognized rattlesnake taxa, including distinct species and subspecies. These snakes are broadly grouped based on their general size and the type of habitat they occupy.
Desert Basin Giants and Widespread Species
The Western Diamondback Rattlesnake (Crotalus atrox) is the largest and most widespread species in Arizona. It is known for its alternating black and white tail bands (“coon tail” markings) and distinct diamond-shaped blotches, and is common throughout the desert valleys and lower mountain slopes across the southern half of the state. The Mojave Rattlesnake (Crotalus scutulatus) is found primarily in the northwestern and south-central deserts. It is identified by narrow light bands on its tail (smaller than the dark bands) and is known for its potent venom.
The Sidewinder (Crotalus cerastes) is a smaller, slender snake recognizable by its unique sideways looping locomotion and small, horn-like projections above its eyes. It is a desert specialist inhabiting the sandy flats and dunes of the Sonoran and Mojave deserts. The Blacktail Rattlesnake (Crotalus molossus) is found in the rocky uplands and southeastern mountain ranges. It is named for its uniformly black tail that contrasts sharply with its lighter body coloration.
Montane and Plateau Specialists
Several rattlesnake types specialize in Arizona’s higher-elevation habitats and plateaus. The Arizona Black Rattlesnake (Crotalus cerberus) is found in high mountains and forested areas, often above 6,000 feet, and adults are typically a uniform dark brown or black. The Grand Canyon Rattlesnake (Crotalus oreganus abyssus) is an isolated subspecies inhabiting the inner gorge of the Grand Canyon. It is often pink, salmon, or red, camouflaged against the canyon’s geological layers.
The Hopi Rattlesnake (Crotalus viridis nuntius) is a small, pale subspecies found on the northeastern plateaus, including the Hopi Mesas. Its coloration is highly variable, often matching the reddish or grayish soil of its range. The Twin-spotted Rattlesnake (Crotalus pricei) is a small, secretive species found exclusively in the southeastern sky islands, characterized by a pair of dark spots or blotches down its midline. The Banded Rock Rattlesnake (Crotalus lepidus) is a slender, medium-sized snake found on rocky slopes and canyons, distinguished by thin, dark crossbands over a grayish or pinkish background.
Rare and Cryptic Species
Two of the smallest and most geographically restricted rattlesnakes are the Arizona Ridge-nosed Rattlesnake (Crotalus willardi willardi) and the Desert Massasauga (Sistrurus tergeminus edwardsii). The Ridge-nosed Rattlesnake, the Arizona State Reptile, has a unique upturned scale on the tip of its snout and is restricted to the southeastern mountain ranges near the Mexican border. The Desert Massasauga is a federally protected, small rattlesnake found only in the extreme southeastern grasslands. It belongs to the Sistrurus genus, possessing nine large scales on top of the head rather than the smaller scales seen in Crotalus.
Rounding out the 13 are the Tiger Rattlesnake (Crotalus tigris) and the Speckled Rattlesnake (Crotalus pyrrhus). The Tiger Rattlesnake is a slender, medium-sized snake endemic to the Sonoran Desert, known for its small head and dark crossbands near its tail that resemble tiger stripes. The Speckled Rattlesnake is found on rocky hillsides and canyons across the western and southwestern parts of the state. Its coloration is highly variable, often matching the color of the rock and gravel of its surroundings.
Living Safely Alongside Arizona’s Rattlesnakes
Coexisting with rattlesnakes requires awareness and non-confrontation. Most bites occur when a person attempts to harass, handle, or kill a snake, which is a defensive reaction. Rattlesnakes are not aggressive and use their rattle primarily as a warning to deter threats.
Simple precautions reduce the risk of an encounter, especially during warmer months when snakes are most active. When hiking, remain on established trails and always look where you place your hands and feet, avoiding reaching into rock crevices or dense brush. At night, when many species are active to avoid the desert heat, carrying a flashlight and wearing sturdy footwear is recommended.
Homeowners can minimize close-range encounters by modifying their immediate habitat. This involves removing potential hiding places near the home, such as piles of wood, debris, or dense, low-lying shrubbery. If a rattlesnake is spotted, calmly and slowly back away, maintaining a distance of at least three to five feet, and allowing the snake to move on its own. Attempting to move or handle any rattlesnake, even if it appears dead, is dangerous, as reflex strikes can occur hours after death.