Most adult Brown Watersnakes are about 30-60 inches (76-152 cm) in total length. These stout-bodied snakes are light tan with squarish darker brown blotches down the middle of the back. Dark squarish markings also extend upwards from the belly onto the sides of the body between the blotches on the back. The head is large and distinct from the neck. Juvenile coloration is similar to that described for adults.
Adult Brown Watersnake. Photo courtesy of Todd Pierson.
Dark Adult Brown Watersnake showing strongly keeled scales. Photo courtesy of Luke Smith.
Juvenile Brown Watersnake. Photo courtesy of Noah Mueller.
Range in Florida
Brown Watersnakes are found throughout mainland Florida in every county. However, they are absent from the Florida Keys.
Assessment of risk to people and pets
Non-venomous. Brown Watersnakes are not dangerous to people or pets, but they will readily bite to defend themselves. These snakes are not aggressive and avoid direct contact with people and pets. Virtually all bites occur when the snakes are intentionally molested.
Comparison with other species
Florida Cottonmouth (Agkistrodon conanti)Venomous If the head is viewed from above, the eyes of cottonmouths cannot be seen while the eyes of watersnakes are visible. Cottonmouths have vertically elliptical (cat-like) pupils, whereas watersnakes have round pupils. Cottonmouths have a facial pit between the nostril and the eye, whereas watersnakes do not.
Florida Cottonmouth. Photo courtesy of Luke Smith. Adult Brown Watersnake. Photo courtesy of Todd Pierson.
Saltmarsh Watersnake (Nerodia clarkii) Non-venomous Saltmarsh Watersnakes often have several dark stripes running down the entire or partial length of the body, and they are usually only found along the coast in saltwater and brackish habitats.
Saltmarsh watersnake. Photo courtesy of Luke Smith. Adult Brown Watersnake. Photo courtesy of Todd Pierson.
Florida Green Watersnake (Nerodia floridana)Non-venomous Florida Green Watersnakes are dark green and have scales between the eye and the scales on the upper lip.
Florida Green Watersnake. Photo courtesy of johnjinjohny/iNaturalist Adult Brown Watersnake. Photo courtesy of Todd Pierson.
Midland Watersnake (Nerodia sipedon pleuralis)Non-venomous Midland Watersnakes have fewer than 30 darker brown crossbands near the neck, which break up into alternating blotches further down the body, and the belly is yellowish marked with two rows of half-moons.
Midland Watersnake. Photo courtesy of hunterewgley/iNaturalist Adult Brown Watersnake. Photo courtesy of Todd Pierson.
Southern Watersnake (Nerodia fasciata)Non-venomous Southern Waternsnakes have broad black, brown, or red crossbands (often bordered with black) down the back and a dark stripe that extends from the eye to the angle of the jaw.
Dark adult Southern Watersnake performing defensive head flattening. Photo courtesy of Luke Smith. Adult Brown Watersnake. Photo courtesy of Todd Pierson.
Most adult Brown Watersnakes are about 30-60 inches (76-152 cm) in total length, with a record length of 69.5 inches (176.6 cm). These stout-bodied snakes are light tan with darker squarish brown blotches down the middle of the back. Dark squarish markings also extend upwards from the belly onto the sides of the body between the blotches on the back. The belly is light-colored with darker blotches and half moons. The scales are strongly keeled (each scale has a prominent raised ridge), and there are 25-33 dorsal scale rows at midbody. The head is large and distinct from the neck, and the pupil is round. Juvenile coloration is similar to that described for adults.
In Florida, Brown Watersnakes are commonly found in rivers, cypress strands, sawgrass prairies, swamps, lakes, ponds, canals, and flooded stands of melaleuca. Adults and juveniles of this species are occasionally found in suburban neighborhoods where development encroaches into favorable habitats.
When approached, Brown Watersnakes will typically flee into the water and dive below the surface. If grabbed or pinned, they will typically bite the attacker and release a foul-smelling musk from a pair of glands in the base of the tail. Nonetheless, these snakes are not aggressive, and striking is only used in defense as a last resort.
Brown Watersnakes feed almost exclusively on freshwater fishes, especially catfishes. These snakes are not constrictors and overpower their prey by grabbing it in their jaws, hauling it to shore, and swallowing it after it has been subdued. Brown Watersnakes are typically diurnal (active during the day) during the spring and fall, but they become more active at night during the hot summer months.
In Florida, females typically give live birth to 4-61 young in late summer or early fall.
Brown Watersnakes are excellent climbers and can be found 20 feet up in trees, though they are most frequently seen basking on tree limbs that extend over the water. When frightened by a rapidly approaching boat, these snakes will escape by jumping off the limb into the water. Occasionally their attempts to flee come too late and they fall not into the water but into the boat.
Unfortunately, many watersnakes are killed every year by Florida residents who mistake them for cottonmouths. Although cottonmouths occur throughout Florida, they are not nearly as abundant as the eight species of harmless watersnakes (species in the genus Nerodia) that occur in much the same habitats. If you see a snake in or near the water, most likely it is a harmless watersnake, and it is best for everyone involved to simply leave it alone.
County data coming soon.
If you have a new or interesting observation for this species, please email the herpetology staff at the Florida Museum.
Ernst, C.H. and E.M. Ernst. 2003. Snakes of the United States and Canada. Smithsonian Institution Press, Washington, DC. 668 pp.
Gibbons, J.W. and M.E. Dorcas. 2004. North American Watersnakes: A Natural History. University of Oklahoma Press, Norman, Oklahoma. 438 pp.
Krysko, K.L., K.M. Enge, and P.E. Moler. 2019. Amphibians and Reptiles of Florida. University of Florida Press, Gainesville, Florida. 706 pp.
Powell, R., R. Conant, and J.T. Collins. 2016. Peterson Field Guide to Reptiles and Amphibians of Eastern and Central North America. Fourth edition. Houghton Mifflin Harcourt Publishing Company, Boston and New York. xiv + 494 pp.
Still have questions about snakes or identifications? Feel free to email the herpetology staff at the Florida Museum with your questions or feedback on this profile.
Banner photo courtesy of Todd Pierson. Please credit any photographers on the page and see our copyright policy.
