The Water Moccasin, scientifically known as the Cottonmouth (Agkistrodon piscivorus), is a venomous snake often associated with aquatic environments. A common question for residents and visitors to the Southwest is whether this species inhabits the region. The definitive answer is that Water Moccasins are not native to, nor are they found in, the state of Arizona. This pit viper’s natural range is geographically restricted to the wet, humid areas of the Southeastern United States.
Where Water Moccasins Truly Live
The native distribution of the Cottonmouth is confined to the swampy lowlands of the country’s southeast, extending west only as far as eastern Texas and parts of Oklahoma. This semiaquatic viper is the only venomous water snake in North America, thriving in habitats that are consistently wet and warm. They are commonly found in sluggish streams, marshes, cypress swamps, and the shores of lakes and ponds throughout the Coastal Plain.
The required habitat for the species includes slow-moving, shallow water bodies with plentiful vegetation for cover and basking. Arizona’s environment, characterized by arid deserts, mountainous terrain, and often ephemeral water sources, does not meet these specific ecological needs. The climate and elevation across the vast majority of the state are incompatible with the snake’s survival and reproduction. Therefore, any sighting of a snake in Arizona’s water is a misidentification of another, locally established species.
Common Misidentified Arizona Water Snakes
The snakes most frequently mistaken for Water Moccasins in Arizona are harmless species that naturally live near water. Garter Snakes (Thamnophis species), such as the Sonoran Garter Snake or the Blackneck Garter Snake, are often the source of confusion. These slender, non-venomous snakes are frequently seen swimming or foraging along the banks of rivers, irrigation canals, and permanent streams.
Garter Snakes can be darkly colored, especially when wet, which contributes to the misidentification with the darker-hued Cottonmouth. The Checkered Garter Snake is another commonly encountered species that may be found near water. These snakes possess a distinct pattern of light spots on a darker background, but like other garter snakes, they are entirely non-venomous. It is the combination of their presence in water and their dark coloration that frequently triggers the mistaken identity.
Another behavior that causes concern is the defensive posture of many harmless snakes. When threatened, species like the Gopher Snake or certain Kingsnakes can flatten their heads and bodies, making their heads appear triangular and blocky, mimicking the characteristic shape of a pit viper.
Arizona’s Native Venomous Species
While the Water Moccasin is absent, Arizona is home to a variety of native venomous snakes, with the rattlesnake being the most prevalent concern. The state has the highest number of rattlesnake species in the United States, with approximately 13 types found across its diverse landscapes. These pit vipers belong to the genus Crotalus and are found in nearly every habitat, from the desert floor to high mountain forests.
The most common and widely distributed of these is the Western Diamondback Rattlesnake, which can be found in the arid and semi-arid regions of the state. Other notable species include the Mojave Rattlesnake, known for having particularly potent venom, and the Sidewinder, which is adapted to moving across sandy desert terrain. These rattlesnakes possess the heat-sensing pits and triangular head shape that people associate with the Cottonmouth.
The only other native venomous snake in Arizona is the small and reclusive Sonoran Coral Snake. This species is easily recognizable by its distinct bands of red, black, and yellow. Unlike the rattlesnakes, the Coral Snake is not a pit viper and possesses a different type of venom delivery system, but it should still be treated with extreme caution.