Oklahoma is situated in the South-Central region of the United States. It falls within the drainage basins of the Red River and the Arkansas River, with their many tributaries extending throughout the state, characterized by their clay or sandy substrate. The state has a humid subtropical climate in the east, while the west is semi-arid.
A variety of habitats can be found within Oklahoma: mountain foothills, oak-hickory forests, grasslands, scrublands, and swamps are interspersed with ponds, lakes, and rivers. This combination of features means there is plenty of suitable habitat for a wide range of aquatic snakes. Some of the species found in the state are only partially aquatic, whereas others spend the entirety of their lives in the water.
Oklahoma Water Snakes
1) Common water snake (Nerodia sipedon)
- Native to eastern and central North America
- Family: Colubridae
- Order: Squamata
- Conservation status: Least concern
The common water snake can grow up to 140 cm (4 ft 7 in) and is typically brown, reddish, or gray in color, although individuals tend to darken with age. There may be patterning across the dorsum, although this is highly variable, and the underside is paler in color – usually cream or yellow.
This species is fairly adaptable in terms of habitat, occupying lakes, streams, rivers, and marshes. It uses its habitat to thermoregulate: research has found that individuals spend more time basking when the air temperature is higher than the water temperature. Common water snakes hunt at the water’s edge, consuming fish, frogs, salamanders, small mammals, and birds.
Common water snakes use chemosensory cues to detect their prey; their preferences have been found to be related to recent feeding experiences, although have also been suggested to vary with their size and age.
2) Cottonmouth (Agkistrodon piscivorus)
- Native to the southeastern US
- Family: Viperidae
- Order: Squamata
- Conservation status: Least concern
The cottonmouth is a venomous, semi-aquatic snake that can grow to lengths of 122 cm (4 ft), with the males typically being larger than the females. This species has a heavy build and varies in color from yellow to dark brown – some individuals have dark crossbands, while others do not. The tip of the tail is yellow in juveniles, a feature that they use to attract prey.
Agkistrodon piscivorus can be found in the riparian zone, where it basks on rocks at the water’s edge. It hunts both terrestrially and aquatically and tends to use the water as an escape route if threatened. During the spring and summer, these snakes have been found to prefer areas with a greater abundance of vegetation.
Interestingly, the size and shape of the cottonmouth’s head have been found to be sexually dimorphic, reflecting differences in the prey each sex tackles. For example, males have longer quadrate bones and tend to consume taller prey relative to their body size than females.
3) Plain-bellied water snake (Nerodia erythrogaster)
- Native to the southeastern US
- Family: Colubridae
- Order: Squamata
- Conservation status: Least concern
The plain-bellied water snake can grow up to 120 cm (3 ft 11 in) in length and is dark green, gray, or brown in color with a yellow belly. Juveniles can be distinguished from adults as they have strong brown stripes or spots across the dorsum – these patterns fade with age, and older adults can be quite pale in color.
This species resides in woodland ponds or drainage ditches, although it seems to be sensitive to aquatic pollution and cannot be found in waters contaminated with industrial waste. Individuals consume a varied diet of fish, amphibians, and crayfish, although appear to have a particular preference for leopard frogs.
If threatened, the plain-bellied water snake will fight back and bite. Although it is non-venomous, it is often mistaken for the cottonmouth and killed out of fear. If captured, individuals secrete musk from glands on the tail.
4) Banded water snake (Nerodia fasciata)
- Native to the eastern US
- Family: Colubridae
- Order: Squamata
- Conservation status: Least concern
The banded water snake is large, growing to lengths of 150 cm (4 ft 11 in). This snake has a heavy build and is brown or gray in color, with reddish-colored stripes across the body, and some scattered spots on their underside. Close examination of the face reveals a dark stripe running from the eye to the jaw.
This species can be found throughout Oklahoma, commonly residing in marshes and ponds. Individuals feed on fish, frogs, and salamanders – as they swallow their prey whole, they have to protract their jaw to consume it. A study found that larger, wider prey required more movement of the bones in the snake’s head.
Nerodia fasciata displays two types of movement: concertina locomotion, and sidewinding. Concertina locomotion is typically used when the snake is moving along a tunnel, whereas sidewinding tends to be used when the snake is on a loose substrate.
5) Diamondback water snake (Nerodia rhombifer)
- Native to the southeastern US
- Family: Colubridae
- Order: Squamata
- Conservation status: Least concern
The diamondback water snake reaches a maximum length of 150 cm (4 ft 11 in) and has a thickset build. Its coloration is green or brown with dark blotches connected by bars – this produces a diamond-like patterning across the dorsal surface. The underside of this snake is yellow with scattered dark spots.
This species is relatively adaptable in terms of habitat, occupying ponds, streams, and rivers in both undisturbed and urban areas. It feeds on a varied diet including crayfish, amphibians, fish, and carrion. Nerodia rhombifer have been observed to engage in two different feeding patterns: one in which they consume one large prey item, or alternatively, consume several smaller prey items in quick succession.
Diamondback water snakes can often be observed on low-hanging branches over water – individuals use these to bask on, but if disturbed will immediately drop down and escape into the water. These snakes can be revealed at night by shining a torch on the water.
6) Graham’s crayfish snake (Regina grahamii)
- Native to the Central US
- Family: Colubridae
- Order: Squamata
- Conservation status: Least concern
The Graham’s crayfish snake can attain lengths of up to 120 cm (3 ft 11 in), although individuals are generally found to be much smaller. It is generally brown or gray in coloration, with a tan-colored dorsal stripe and yellowish stripes along the sides. The underside is cream or yellow.
This species is semi-aquatic, residing in crevices or crayfish burrows near bodies of water, and basking on branches overhanging ponds or streams. Graham’s crayfish snakes are highly specialized predators, feeding only on molting crayfish. These snakes have in-built chemosensory preferences, that enable them to locate their prey.
The range of Graham’s crayfish snake within Oklahoma extends through the center of the state and into the Red River drainage, but it is also occasionally found in urban areas. The stability of this species is currently unknown and is in need of further assessment.
7) Mud snake (Farancia abacura)
- Native to the southern US
- Family: Colubridae
- Order: Squamata
- Conservation status: Least concern
The mud snake is large, reaching lengths of up to 207 cm (6 ft 9 in). It is a highly secretive species, and as such is rarely seen, however, it can be identified by its glossy back and red belly, which is overlain by a black chequerboard pattern. The sides are red, and there may be some yellow on the head. Individuals also have a spine at the end of their tails.
As well as being reclusive, mud snakes are rare in Oklahoma, making them even harder to spot. Populations can be fairly adaptable in terms of habitat, occupying swamps, marshes, streams, and ponds – although they do prefer areas with plenty of vegetation in which they can hide. The diet of this species includes eels, salamanders, and frogs.
In response to predators, mud snakes have been observed to roll over onto their backs to reveal their brightly colored underside – this coloration mimics that of some poisonous snake species. Individuals may also pretend to be dead, or even crawl away upside down, in an attempt to avoid predation.
8) Black swamp snake (Seminatrix pygaea)
- Native to the southeastern US
- Family: Colubridae
- Order: Squamata
- Conservation status: Least concern
The black swamp snake is fairly small, reaching just 55 cm (1 ft 10 in) in length, with females tending to be larger than males. With a black back and a bright red belly, this species is often confused with the mud snake – however, Seminatrix pygaea can be distinguished by the lack of the chequerboard pattern on its underside, which is present in the mud snake. The scales of the black swamp snake are incredibly glossy.
This snake is highly aquatic and can typically be found residing in drainage ditches or along the margins of lakes and ponds. It prefers areas with plenty of aquatic vegetation and is often more abundant in water bodies that periodically dry out. These areas lack fish and are home to many amphibians, which the black swamp snake’s diet is primarily composed of. Individuals may also feed on leeches and worms.
Black swamp snakes are viviparous, giving birth to live young between July and August. Research has found that the reproduction of this species is highly predictable and lacks variation, even when weather conditions fluctuate from year to year.
9) Common garter snake (Thamnophis sirtalis)
- Native to the US, Canada, and Mexico
- Family: Colubridae
- Order: Squamata
- Conservation status: Least concern
The common garter snake is usually found at lengths of 46 – 66 cm (1 ft 6 in – 2 ft 2 in), but individuals have been found to grow to 124 cm (4 ft 1 in). This snake’s body color is usually dark gray, with three yellow stripes running down the length of the body and tail, however, some individuals are lighter gray or reddish in color, with a chequerboard pattern.
Thamnophis sirtalis is often found near water bodies such as ponds or streams, although also commonly resides in meadows and marshes. Being only semi-aquatic, individuals can occasionally be found far from water. If temperatures on the ground are low, common garter snakes will climb trees to access warmer conditions.
Temperature has a significant impact on the behavior of the garter snake. Individuals’ antipredator responses vary depending on the air temperature: warmer snakes show greater aggression in response to a threat, whereas colder snakes will perform more passive behaviors such as hiding their head and coiling their tail.
10) Crayfish snake (Regina rigida)
- Native to the southeastern US
- Family: Colubridae
- Order: Squamata
- Conservation status: Least concern
The crayfish snake grows to 36 – 61 cm (1 ft 2 in – 2 ft) in length and has a stout build with a small head and large eyes. Its scales are glossy and brown or olive in color, with two paler stripes running down the body. The underside is yellow with two lines of dark spots running along the length of the snake.
This species is highly secretive, and due to its aquatic habits is very rarely seen. It prefers well-vegetated ponds and lakes, or drainage ditches, where it feeds on molting crayfish. During their molt crayfish extract nutrients such as calcium from their exoskeleton and store it in their stomachs – they are particularly vulnerable at this time due to lacking their usual protection, making them easy prey for crayfish snakes.
Populations of crayfish snakes are stable, however, they may be at risk of decline due to the destruction of habitat – not only would this remove suitable locations for the snakes themselves, but it would reduce the abundance of the crayfish on which they rely.
