Rattlesnakes are found in Iowa, though encounters are uncommon. The state is home to a few reclusive species, all protected under Iowa law. This protection helps conserve populations facing habitat loss and human activities.
Rattlesnake Species in Iowa
Iowa hosts two primary rattlesnake species: the Timber Rattlesnake (Crotalus horridus) and the Eastern Massasauga (Sistrurus catenatus). A third, the Prairie Rattlesnake (Crotalus viridis), is extremely rare and localized to a small area.
The Timber Rattlesnake is typically larger, ranging from 36 to 60 inches. Their bodies can be yellow, tan, brown, or gray, marked with distinct dark brown or black chevron-shaped crossbands. Many Iowa Timber Rattlesnakes also feature a rust or orange-brown stripe down the center of their back. Their tails are solid black with a light-colored rattle, a distinguishing feature from other Iowa snakes.
The Eastern Massasauga is a smaller, stout-bodied rattlesnake, generally measuring between 18 and 30 inches. They have a gray or light brown background with large, dark chocolate-brown blotches, often outlined in white, and smaller spots along their sides. Their tails have dark bands near the rattle, which is notably small and difficult to hear unless close by. Both rattlesnake species possess a spade-shaped or triangular head and vertical, cat-like pupils, distinguishing them from most non-venomous Iowa snakes.
Preferred Habitats and Distribution
Rattlesnakes in Iowa occupy specific habitats, contributing to their localized distribution. The Timber Rattlesnake typically prefers forested bluffs, rocky outcrops, and river valleys. They are often found in eastern and southern Iowa, particularly along the Mississippi River and its tributaries. These snakes utilize sunny, open areas for basking and often overwinter communally in dens within bluff sides or rock crevices.
The Eastern Massasauga has a more restricted and fragmented distribution, primarily found in wetland environments like wet prairies, bogs, marshes, and low areas along rivers and lakes. While they primarily inhabit these wet areas, they may move to drier, upland habitats during warmer months. Massasaugas are reclusive, often seeking shelter under logs, rocks, or in small mammal and crayfish burrows, and typically hibernate alone. The Prairie Rattlesnake, exceptionally rare, is known from only one small population in the Loess Hills region of northwestern Iowa, preferring large, open prairie and grassland environments.
Safety and Coexistence
Minimizing the risk of encountering rattlesnakes in Iowa involves awareness and caution, particularly when outdoors in their known habitats. Stay on marked trails and watch where you step, especially in areas with dense vegetation or rocky terrain. Avoid placing hands or feet into unseen crevices, under logs, or thick brush, as these are common hiding spots. Wearing sturdy, over-the-ankle boots and long pants offers a layer of protection.
If a rattlesnake is encountered, maintain a respectful distance. They are generally not aggressive and will attempt to avoid humans, often rattling as a warning when disturbed. Do not provoke or attempt to handle the snake, even if it appears dead, as reflexive bites are possible. Allow the snake to move away or give it a wide berth if it remains coiled.
In the unlikely event of a rattlesnake bite, immediate medical attention is essential; remain calm and move to a safe location away from the snake. Remove any constricting clothing or jewelry from the affected limb, and gently wash the bite area with soap and water if available. Keep the bitten area below heart level to help slow venom spread. Avoid applying ice, tourniquets, cutting the wound, or sucking out venom, as these actions can cause further harm. Contact the Iowa Poison Control Center at 1-800-222-1222 for guidance while en route to a medical facility.