Discover the Invasive Watersnakes Invading Arizona

Written by Emmanuel Kingsley
Published: May 23, 2022
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Arizona is known for its snakes and vegetation. Officially, the state houses over 40 species of snakes, 21 of which are venomous. Phoenix is said to have the highest number of snakes. Places such as Gold Canyon, north Scottsdale, and other open-space areas in Phoenix, Arizona see more snakes than others. Previously, Arizona had no established watersnake species. However, recent sightings hint that that might be changing. Discover the invasive watersnakes invading Arizona.

Invasive Watersnakes Invading Arizona

In 2016, published an article detailing a new snake invasion sighting. KJZZ is a service of Rio Salado College and Maricopa Community Colleges. The article stated that Arizona officials had spotted an invasion of southern banded watersnakes at Mittry Lake which is north of Yuma on Laguna Dam Road as well as other Colorado rivers in the Yuma area.

Colorado rivers contain a lot of cattails and stagnant water. For this reason, southern banded watersnakes like them as they are similar to Florida, where they are native. According to, Richard Meyers, an Arizona Game and Fish wildlife manager, reports that over twenty southern banded watersnakes have been collected and hinted that there were probably thousands more in the ocean.

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Southern Banded Watersnakes (Nerodia fasciata)

Although southern banded watersnakes are mistaken for cottonmouths,they are nonvenomous colubrid snakes.

©Deborah Ferrin/

Southern banded watersnakes are colubrid snakes that are native to the Midwest and the southeastern United States. Although they are often mistaken for cottonmouth snakes, they are non venomous and harmless. Southern banded watersnakes found in southern habitats are active throughout the year. However, in other locations, they hibernate during the winter.

These aquatic snakes are excellent swimmers and can stay underwater for up to 2 hours after taking a deep breath of air. They are widespread and are consequently rated as “Least Concern” by the IUCN RedList.

How to Identify Southern Banded Watersnakes

Southern banded watersnakes grow to average sizes of 2 to 3.5 feet and weigh an average of 16.4 ounces.


Southern banded watersnakes grow to average sizes of 2 to 3.5 feet, with a maximum of 5 feet. They are usually gray to greenish-gray or brown to tan in color. They also have dark crossbands that run along their bodies. They are wider around their backs but thin out on the sides.

Several southern banded watersnakes have crossbands that are so dark that they are hard to see. They usually have white bellies and flat bodies. They weigh just over a pound or 16.4 ounces on average. Due to their appearances, they are often mistaken for venomous cottonmouth snakes.

Where Do Southern Banded Watersnakes Live?

Southern banded watersnakes are often found near ponds, streams, and rivers. They also choose areas with vegetation and shallow waters such as swamps, wetlands, and ditches.

Are Southern Banded Watersnakes Dangerous?

Southern banded watersnakes aren’t venomous. However, this doesn’t mean that they are entirely harmless. If they feel threatened, they are known to bite painfully and repeatedly, even as babies! Their bites pierce mercilessly through skin and clamp onto a chunk of it. Then, they snatch their heads back, ripping the skin apart.

These snakes aren’t friendly and are quick to bite if they feel the need to. Also, before they bite, they often spray a foul-smelling musk. If you’re musked by a southern banded watersnake, get away from it as fast as you can. Southern banded watersnakes also have dangerous effects on the ecosystem.

Arizona’s Invasive Southern Banded Watersnakes

Arizona’s invasive southern banded watersnakes are a threat to giant garter snakes.

©Deborah Ferrin/

Arizona’s watersnakes, like Mississippi’s invasive species and Burmese pythons in Florida, have negative effects on Arizona’s ecosystem. These watersnakes eat a lot of animals such as frogs, fish, small birds, and small snakes. They also eat worms, turtles, and various crustaceans and amphibians.

Southern banded watersnakes hunt through the use of their Jacobson’s organ. Also called the vomeronasal organ, it is a part of the watersnake’s olfactory system. It is a patch of sensory cells used to communicate chemical messages. It is also used to hunt and track prey.

Southern banded watersnakes are also highly adaptable to various habitats such as brackish water, and since they have high reproduction rates, a female watersnake could give birth to 20 snakes in a single cycle. Due to these characteristics, southern watersnakes are no match for some of the native species of Arizona.  

One of Arizona’s species that raises the most concern is the giant garter snake (Thamnophis gigas). The giant garter snake is a native Arizona species that inhabits wetlands and preys on amphibians such as tadpoles, frogs, and fishes. Their diets and habitats are very similar to the southern banded watersnake. The presence of the southern watersnake means giant garter snakes have more competition for food and habitats.

This is an extremely concerning situation because giant garter snakes are a threatened species. Southern banded watersnakes, unlike giant garter snakes which are docile like most garter snakes, can get aggressive when hunting, giving them the upper hand. The presence of these snakes is a threat to the efforts of the state of Arizona to recover the giant garter snake species.

What To do if You’re Bitten By A Southern Watersnake

Although southern watersnakes are non venomous, it is still important to contact emergency services immediately if you get bitten by one. Apart from the pain, wounds can get infected if they are not well treated. There is also the possibility of misidentifying a venomous snake as a nonvenomous one (e.g., a cottonmouth as a southern banded snake.) so it is better to be on the safe side.

What Should You Do If You Spot an Invasive Snake Species in Arizona?

If you spot an invasive snake species in Arizona, do not attempt to kill or capture it if you’re untrained. Instead, contact the Arizona Fish and Wildlife Conservation Office (AZFWCO) – formerly the Pinetop Fishery Assistance Office at 602-942-3000. Similarly, if you have one in your possession or no longer want one you kept as a pet, do not release it into the wild. Rather, turn it over to the AZFWCO. 

The ecosystem’s meticulous balance is threatened by the presence of invasive species. The Arizona Fish and Wildlife Conservation Office requests that citizens who frequent the waters keep an eye out for invasive snake infestations and report them to the conservation office.

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Southern/Banded Water Snake
Southern/Banded Water Snake
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