For many people in Iowa, questions about local wildlife, particularly snakes, are common. Curiosity often arises regarding the presence of specific species, such as water moccasins, also known as cottonmouths. This article aims to clarify whether they inhabit the state and offer guidance for identifying and interacting with Iowa’s snake population.
Are Water Moccasins Found in Iowa?
Water moccasins (Agkistrodon piscivorus) are not native to Iowa. Their natural range is primarily the southeastern United States, extending north through southern Missouri, Illinois, and Virginia, and west to central Texas. Iowa lies well outside this habitat, so any sightings likely involve misidentification.
Commonly Mistaken Snakes in Iowa
Snakes frequently seen near water in Iowa are often harmless species misidentified as water moccasins. The Northern Water Snake (Nerodia sipedon) is common and often mistaken for a cottonmouth. These snakes range from gray to brown, with darker bands near their heads that transition into blotches. Older individuals may appear solid brown or black.
Northern Water Snakes are found in lakes, ponds, marshes, and streams, often basking on branches or banks. When threatened, they flatten their bodies and heads, appearing larger and more triangular, which contributes to misidentification.
The Diamondback Water Snake (Nerodia rhombifer) is another species sometimes confused with the water moccasin, though it is less common and primarily found in southeastern Iowa. These snakes have a greenish, olive, brownish, or grayish color with a distinctive chain-like pattern. Their bellies are often yellow or cream with brown half-moon shaped markings. Diamondback Water Snakes inhabit slow-moving bodies of water and can deliver a painful, non-venomous bite if provoked. Both species will bite defensively if threatened.
Identifying True Water Moccasins
Distinguishing water moccasins from harmless water snakes involves observing several key characteristics. A true water moccasin has a large, blocky, triangular head notably wider than its neck. Its eyes cannot be seen from directly above due to an overhanging brow ridge, and pupils are vertical, resembling a cat’s eye.
As pit vipers, water moccasins also have heat-sensing pits between their nostrils and eyes. Their bodies are heavy and thick for their length, ending in a short, stout tail. Coloration varies, often dark brown or black in adults, while juveniles typically exhibit distinct crossbands and a unique sulfur-yellow tail tip. A threatened water moccasin may perform a “cottonmouth” display, opening its mouth wide to reveal a stark white interior as a warning. They also tend to swim with most of their body floating on the water’s surface, unlike many non-venomous water snakes that swim with only their heads visible.
Safe Encounters with Iowa Snakes
Encountering snakes in Iowa, whether near water or on land, calls for a calm and respectful approach. Most snakes found in Iowa are harmless and play an important role in the ecosystem. If you come across a snake, observe it from a distance and avoid attempting to handle or provoke it. Snakes bite only when they feel threatened or are cornered.
Trying to kill a snake can increase the risk of being bitten. Allowing the snake to move away on its own is the safest course of action. If a snake is in a location where it poses a direct threat, such as inside a home or building, contact local wildlife authorities or animal control for safe removal. Coexisting with these animals means respecting their space and understanding their natural behaviors.