The Brazos Water Snake, scientifically known as Nerodia harteri, is a non-venomous species found exclusively within the Brazos River basin in Texas. Named after the Brazos River, this aquatic reptile is a common resident of the state’s river systems.
Identifying the Brazos Water Snake
The Brazos Water Snake typically measures between 16 and 32 inches in total length, though some individuals may reach up to 2.5 feet. Its coloration can vary, presenting as a mix of brown and gray, or a combination of green and brown. A distinguishing feature is the presence of four rows of dark dorsal spots running along its body, creating a checkerboard-like pattern.
The snake’s belly is often a pink or orange color, with dark spots along each side of the belly scales. Its neck may also display a yellow or cream hue. The Brazos Water Snake has keeled scales, which possess a ridge down the middle. Its head is typically rounded.
Habitat and Habits
This species shows a strong preference for fast-flowing, rocky waters that are relatively free of dense vegetation. This species takes shelter under rocks in the water or in vegetation along the shoreline. Juveniles often utilize flat rocks on unshaded shores for hiding and rocky shallows for feeding, while adults can be found in rocky riffles, as well as pools and lakes.
As a daytime hunter, the Brazos Water Snake primarily preys on small fish. However, its diet also includes amphibians such as frogs and salamanders, and crustaceans like crayfish. When encountered or startled, these snakes almost always retreat directly into the water. The species is recognized as threatened by the Texas Parks and Wildlife Department and is protected by state law.
Distinguishing from Venomous Look-Alikes
Distinguishing the non-venomous Brazos Water Snake from venomous snakes, particularly the Cottonmouth (Agkistrodon piscivorus), is important for safety. Cottonmouths generally have a more triangular-shaped head, noticeably wider than their neck, due to prominent venom glands, whereas the Brazos Water Snake has a more rounded or slender head. While water snakes may flatten their heads when threatened to appear larger, their natural head shape is different.
Another key difference lies in the pupils: Cottonmouths possess vertical, slit-like pupils, similar to a cat’s eye, while the Brazos Water Snake has round pupils. Cottonmouths also have heat-sensing pits located between their eyes and nostrils, which are absent in the Brazos Water Snake.
In terms of body shape, Cottonmouths are typically stouter and heavier-bodied, while Brazos Water Snakes are more slender. When swimming, Cottonmouths often float with most of their body on the surface, whereas non-venomous water snakes typically swim with only their head visible. If disturbed, a Brazos Water Snake will usually attempt to flee into the water, unlike a Cottonmouth which might display a defensive posture, opening its mouth to show a white interior.