Alabama is one of the states with the highest species diversity of snakes. A total of 44 species can be found slithering around. 6 of these are venomous and 13 are semi-aquatic (one of them also being venomous). While all snakes can technically swim since the side-to-side movement they use on land makes them abled swimmers, the ones in this article acquire most of their diet from hunting in aquatic habitats.
Snakes are ectothermic, which means they obtain their body heat from their environment. Therefore, a cost relating to the semi-aquatic lifestyle is the sudden cooling of the body when the snake enters cold water.
Alabama is one of the most biologically diverse states, encapsulating a broad variety of natural habitats from forests, woodlands and prairies to wetlands and glades. The rich assortment of local environments, the complex geological past, and the warm and moist climate is the reason for this diversity.
With temperatures varying from 19°F to 79°F (-7 – 26°C), Alabama offers warm summers and freezing but not intolerable winters. In addition, 77,000 miles of rivers and streams cross through the state creating marine ecosystems for the aquatic snakes to bask in. Alabama is also home to the Mobile-Tensaw River Delta, an intact wetland ecosystem, which ranks among the largest in the United States. Below you will find a list of semi-aquatic snakes in Alabama.
Alabama Water Snakes
1) Brown water snake
- Scientific name: Nerodia taxispilota
- Family: Colubridae
- Subfamily: Natricinae
- Other names: Aspic, false moccasin, great water snake
- Average adult length: 3.5 ft (107 cm)
- Maximum adult length: 5.75 ft (175 cm)
- Threatened status: Least Concern
The brown water snake is common, especially in the south-eastern portion of the Coastal Plain. They are endemic to the southeast USA. They have a light brown base color with darker square-like markings down their back and up their sides. They have round pupils, and the head is distinct from the neck.
They are nonvenomous; however, they are sometimes mistaken for a cottonmouth (water moccasin), which is a venomous snake occurring in the same range. Therefore, one of the common names for this species is ‘false moccasin’. The brown water snake is viviparous, which means that the females give birth to live young.
The brown water snake is piscivorous and seems to prefer catfish. They use two different modes of hunting: sit-and-wait and active foraging. In the first mode, they attach themselves to a solid object, e.g. a branch or root, and attack when their prey moves past. In the second, they enter the water and pursue their prey, while sweeping their heads from side to side.
The brown water snake prefers steep-banked outer banks of rivers, especially with potential perch sites nearby. This could be trees or vines overhanging the water in which they hunt, but larger individuals tend to be found on the bank. They are usually found perching in shade, however in spring they are more commonly found basking in the sun. They seem to prefer being close to deeper, faster waters, as this offers more protection from their aquatic predators, e.g. gar, largemouth bass, or alligators, and a quick escape from avian or terrestrial predators.
2) Cottonmouth
- Scientific name: Agkistrodon piscivorus
- Family: Viperidae
- Subfamily: Crotalinae
- Other names: Water moccasin, moccasin, black moccasin, swamp moccasin
- Average adult length: 3.25 ft (99 cm)
- Maximum adult length: 6.16 ft (188 cm)
- Threatened status: Least Concern
The cottonmouth is the only venomous semi-aquatic snake in North America. Three distinct subspecies are recognized: the eastern, Florida, and western. They have a cross-band pattern with an olive, brown, or black background; as the snakes mature the pattern becomes less visible. They have keeled scales and a dark strip running along the face across the eye.
Warning displays are signals designed to intimidate potential predators or challengers. Two such signals are typically mentioned in connection to vipers: tail-vibrating and gaping. A study on the cottonmouth showed that only gaping is related to subsequent striking. Gaping is therefore an honest warning display. Other non-venomous snakes are often mistaken for cottonmouths. However, the cottonmouth has elliptical pupils, often ride higher in the water than non-venomous snakes, and will present its whitish mouth as a threatening posture.
The cottonmouth’s newborns have a yellow tail tip (as does the copperhead, another venomous Alabama native, however it’s not listed here as it isn’t aquatic), which is used to lure prey within striking range. The yellow tip turns dark as the snake ages. The adult snake is an opportunistic hunter, feeding on both aquatic and terrestrial prey. They strike their target and allow the venom to do the rest before they swallow it.
3) Diamond-backed water snake
- Scientific name: Nerodia rhombifer
- Family: Colubridae
- Subfamily: Natricinae
- Other names: Diamondback water snake
- Average adult length: 3.25 ft (99 cm)
- Maximum adult length: 5.75 ft (175 cm)
- Threatened status: Least Concern
The diamond-backed water snake is endemic to the central US and northern Mexico, and there are three recognized subspecies. They are large with characteristic dark, diamond shapes on their back and sides on a brown background. They occupy a broad ecological niche from freshwater lakes and ponds to rivers, swamps, marshes, and human-made water systems and are mainly active at night. The diamondback is piscivorous with larger snakes preying on larger fish species, but they also eat frogs. Their abundance is tightly correlated with the availability of prey. During the winter, they hibernate in underground burrows.
Individuals are frequently hunted and killed by people in the false belief that this snake species is venomous and potentially dangerous for people. This might be related to their tendency to bite and expel a foul-smelling musk when handled or cornered. The major threats facing this species are the destruction of aquatic habitats and pollution. They appear to be particularly vulnerable to run-offs from agricultural areas, which have historically caused declines in the population numbers. However, the diamond-backed water snake is not considered threatened in most of its range. They have also been observed to re-colonize former ranges, if there is a healthy population within reach.
4) Florida green water snake
- Scientific name: Nerodia floridana
- Family: Colubridae
- Subfamily: Natricinae
- Other names: Eastern green water snake
- Average adult length: 3.54 ft (108 cm)
- Maximum adult length: 6.17 ft (188 cm)
- Threatened status: Least Concern
The Florida green water snake is a large snake endemic to North America. They have stout bodies with dark speckling on a green or brownish background. They have a large head with a row of small scales between the eye and the upper lip. They can be difficult to distinguish from the Mississippi green water snake, however they have a pale belly with no marks. They have large eyes with round pupils, which can differentiate them from the cottonmouth. The Florida green water snake occupies a broad range of aquatic habitats, from natural to artificial. They are not aggressive and avoid contact with people, but they can bite if they are threatened.
In the state of Alabama, the Florida green water snake has only been identified in the Perdido River, a waterway shared with Florida, where the species is under moderate conservation concern. Deeper within the state boundary, only the closely related and visually similar Mississippi green water snake can be found. They are also occasionally mistaken for the venomous cottonmouth; however, the venomous snake has a strongly triangular head. The Florida green water snake primarily feeds on fish and frogs. They breed between June and September, and the females give birth to 20 – 30 young, although a female birthing more than 100 young has been observed!
5) Glossy crayfish snake
- Scientific name: Liodytes rigida or Regina rigida
- Family: Colubridae
- Subfamily: Natricinae
- Other names: Eastern glossy swampsnake, crayfish snake, Gulf crayfish snake
- Average adult length: 1.5 ft (46 cm)
- Maximum adult length: 2.5 ft (76 cm)
- Threatened status: Least Concern
The glossy crayfish snake is a brown to olive-green highly aquatic snake, that can most readily be identified by two rows of dark dots along the ventral scales. The name relates to the preferred prey of the species: the crayfish. The snake has a small head and prefers crayfish of a size that allows them to pass effortlessly through the jaws. The teeth and shape of the skull are coadapted to the handling of prey, and the crayfish snakes have closely set, stout, chisel-like teeth adapted to handle crayfish. The glossy crayfish snake has the least curved and sharp teeth of the crayfish snakes.
Their prey handling behavior includes immobilizing the crayfish by coiling around it and pinning the pinchers, chewing on the abdomen before consuming it from the tail end. The more blunted teeth might be an adaption to the abdominal biting process.
The glossy crayfish snake is rarely seen, as they spend most of their life in and around water. Their preferred habitat includes slow waters in lowland areas, e.g. swamps, ponds, and freshwater marshes. However, they can also be found in grassy or woody upland habitats close to wetlands. The glossy crayfish snake mostly rests in burrows, but it can occasionally be found basking on banks. In wet weather, they may travel over land.
6) Salt marsh snake
- Scientific name: Nerodia clarkii
- Family: Colubridae
- Subfamily: Natricinae
- Other names: Salt marsh water snake
- Average adult length: 1.88 ft (57 cm)
- Maximum adult length: 3 ft (91 cm)
- Threatened status: Least Concern
The salt marsh snake is one of the most recognizable snakes on this list. They have four dark longitudinal stripes running the length of the whole body, which stand out in contrast to its lighter background. The belly is red to brown. They have a high salt tolerance, which allows them to thrive in salty habitats as their name implies. However, they do not have salt glands and therefore lack the ability to expel salt. Because of this, they obtain their water from rainfall and the prey they consume, and must be careful with ingesting too much saltwater.
The salt marsh snake currently exists in numerous subpopulations; however, the overall population trend is declining. The decrease most likely stems from the structure of the subpopulations as some have become isolated due to lack of habitat. They prefer estuarine habitats such as brackish coastal waters and salt marshes, and the population density decreases as the salinity drops upriver. The salt marsh snake hides out in burrows made by crayfish, fiddler crabs or muskrats. The barriers between their natural habitats limit the natural spread of genes between populations and can result in some particularly small populations becoming inbred and scarce. They are threatened by human development, agriculture, aquaculture, and pollution.
7) Midland water snake
- Scientific name: Nerodia sipedon pleuralis
- Family: Colubridae
- Subfamily: Natricinae
- Average adult length: 2.58 ft (79 cm)
- Maximum adult length: 4.29 ft (131 cm)
- Threatened status: Least Concern
The midland water snake is a subspecies of Nerodia sipedon, commonly found throughout Alabama, where they inhabit ponds, marshes, streams, and river valleys. They exhibit a dark crossband pattern right after the head, which develops into a pattern of alternating side and back blotches down the body. The background is a reddish-brown color. They have two distinct rows of reddish half-moons on their yellow belly. The scales are strongly keeled, and the pupils are round. The midland water snake gives birth to between 12 and 30 young that display the same pattern as the adults. The adults do not provide parental care, as the young are independent at birth.
The midland water snake and southern water snake are considered two distinct species based on consistent differences in their morphological characteristics. However, when the ranges of the two species overlap, they are known to interbreed, creating long stretches of hybrid zones. The natural hybridization between the two species has led to extensive research into the genetic as well as physical differences between the two. In separate populations, the color pattern can successfully distinguish the two, however in interbreeding populations, the extent of introgression in intermediate specimens stemming from first-generation hybrids or backcrosses can only be resolved by genetic analysis.
8) Mississippi green water snake
- Scientific name: Nerodia cyclopion
- Family: Colubridae
- Subfamily: Natricinae
- Other names: Green water snake
- Average adult length: 3.54 ft (108 cm)
- Maximum adult length: 6.17 ft (188 cm)
- Threatened status: Least Concern
The Mississippi green water snake is a medium-sized snake that can be found in Mobile and Baldwin Counties. They prefer calm waters like ponds and swamps with dense vegetation, but they can also be found in brackish waters. They can be seen basking on banks close to the water. They are very difficult to distinguish from the Florida green water snake, with their dark olive to brown body and alternating dark blotches. However, the Mississippi green water snake has a yellow-grey belly with half-moon-shaped marks, which the Florida green water snake lacks. They can also be told apart from other snakes by a row of scales between the eyes and lips.
The Mississippi green water snake is tightly connected to swamp systems, and the extensive draining of such habitats and removal of aquatic vegetation have had detrimental effects on this species, especially in the northern part of the natural range. However, the species is currently viewed as stable and not threatened, as they occur in many subpopulations in the southern part of their range, where they are sometimes very abundant. The Mississippi green water snake is active from spring to fall, when the females give birth. They are ovoviviparous, which means that the fertilized egg develops inside the female’s body and lets her give birth to 10 – 20 live young.
9) Mud snake
- Scientific name: Farancia abacura
- Family: Dipsadidae
- Subfamily: Dipsadinae
- Other names: Hoop snake, horned snake, stinging snake, red-bellied mud snake
- Average adult length: 3.94 ft (120 cm)
- Maximum adult length: 6.66 ft (203 cm)
- Threatened status: Least Concern
The mud snake is a large semi-aquatic snake that, despite its size, is rarely seen by people. A western and eastern subpopulation exists, of which the first occurs in the western one-third of the Coastal Plain and the second in the eastern two-thirds. They are black with a bright red and black checkerboard pattern on the ventral side. They can be confused with the North Florida swamp snake (the next on the list), but it has a completely red belly. They are generally considered docile snakes that refuse to bite. However, they do have a spine-like tail end that they can press against their captor’s skin, which is where the common names ‘horned’ and ‘stinging’ snake stems from. Southern folklore also tells that this snake can take hold of its own tail and roll like a wheel, which is not true.
The mud snake inhabits marshes, swamps, and wetlands as well as mud-bottomed streams. As their names imply, they burrow through the mud along the water’s edge in search of prey. They feed almost exclusively on amphiumas and sirens. In contrast to the other snakes on this list, the mud snake lays eggs, sometimes in alligator nests. The female stays with her eggs until they hatch after 8 – 12 weeks.
10) North Florida swamp snake
- Scientific name: Liodytes pygaea earlier Seminatrix pygaea
- Family: Colubridae
- Subfamily: Natricinae
- Other names: Black swamp snake, South Florida swamp snake
- Average adult length: 1 ft (30 cm)
- Maximum adult length: 2 ft (61 cm)
- Threatened status: Least Concern
The North Florida swamp snake is endemic to the south-eastern United States. They are associated with freshwater systems with floating or emergent vegetation, but they can sometimes be found in brackish water. They are black snakes with vibrant red bellies, and this characteristic can distinguish them from most other snakes. They can be confused with the small mud snake (Farancia abacura), but these snakes have a checkerboard pattern on their bellies and the red color stretches up their sides. The North Florida swamp snake exhibits sexual dimorphism with the female being significantly longer and heavier than the males, although the males have thicker tails. The females reproduce either annually or biennially.
The North Florida swamp snake inhabits a broad variety of aquatic habitats. It is a smaller snake feeding on earthworms, frogs, salamanders, small arthropods, and even small fish. They hunt for their prey at night, and it is consumed alive. Despite this ferocious behavior, they are generally docile snakes, avoiding people in a quick escape. If they are cornered, they rarely bite in defense, however, they have two glands at the base of the tail that release a musk with a bad odor, which might make their perpetrator think twice!
11) Plainbelly water snake
- Scientific name: Nerodia erythrogaster
- Family: Colubridae
- Subfamily: Natricinae
- Other names: Plain-belly water snake, redbelly water snake, yellowbelly water snake
- Average adult length: 3.25 ft (99 cm)
- Maximum adult length: 5 ft (152 cm)
- Threatened status: Least Concern
The plainbelly water snake is a large, stout-bodied, semi-aquatic snake with a head that is wider than the neck. They have great variation in their coloration from newborn to mature individuals. The plainbelly water snake gives birth to 5 – 27 young from August to October, measuring 0.62 – 1.08 ft (19 – 33 cm). Juveniles have a distinct pattern with a single row of blotches down the middle of their back. As the snake grows, the blotches become paler, and the background color becomes darker. The mature individuals are highly variable in color, which relates to each subspecies. Their bellies are yellow to reddish, which is where the species name ‘erythrogaster’ comes from, meaning red (erythros) and belly (gaster) in Greek.
The plainbelly water snake lives in aquatic or wetland habitats with permanent or sometimes semi-permanent water. They can often be seen basking in vegetation near the edge of the water. Despite the aquatic lifestyle of this snake, they can be found far from water, especially during warm, wet weather. They occur in many subpopulations and have a broad area of occupancy. While they have been extirpated from some parts of their former range due to habitat destruction, the adult population of plainbelly water snake is stable.
12) Queen snake
- Scientific name: Regina septemvittata
- Family: Colubridae
- Subfamily: Natricinae
- Other names: Brown queen snake, olive water snake, queen water snake, moon snake, leather snake, banded water snake, pale snake, seven-striped water snake, striped water snake, three-striped water snake, willow snake, yellow-bellied snake
- Average adult length: 1.75 ft (53 cm)
- Maximum adult length: 3 ft (91 cm)
- Threatened status: Least Concern
The queen snake is a slender semi-aquatic snake with a narrow head. They are typically a dusty olive or brown color with a yellow or cream lateral band. The young have three light ventral stripes running from head to tail, and four brown stripes on the chin and belly that become indistinguishable near the tail; these patterns fade with age. These colors let them blend in with vegetation as they hide from avian predators like herons and hawks, in addition to terrestrial predators. They prey primarily on crayfish, but can also be prey to crayfish when they are small.
In Alabama, the queen snake is common along many streams above the Fall Line, especially when their preferred prey is abundant. They typically occur in fast-flowing streams with plenty of vegetation and basking sites with high sun exposure, and they seek refuge in burrows, logs, and other types of cover. The queen snake is an extreme dietary specialist. Although they can feed opportunistically, they feed almost solely on freshly molted crayfish. A study presented newly-born queen snakes to the smell of molting crayfish and measured their response. They found that even though these snakes had never eaten crayfish in their life, they exhibited a strong tongue-flicking response and feeding behavior. However, water pollutants can imitate this smell and thereby confuse hunting queen snakes in the wild.
13) Southern water snake
- Scientific name: Nerodia fasciata
- Family: Colubridae
- Subfamily: Natricinae
- Other names: Banded water snake
- Average adult length: 2.75 ft (84 cm)
- Maximum adult length: 5 ft (152 cm)
- Threatened status: Least Concern
The southern water snake is endemic to the southeastern United States but has also been introduced to California and Arizona. The snakes vary in color from light brown or reddish to black with darker crossbands that are larger across the back. The pattern is more distinct in younger individuals. They have thin dark stripes going from the eyes to the jaw. The southern water snake is found in aquatic habitats like ponds, rivers, lakes, marshes, and swamps. They are typically found in shallow, still waters. Between June and August, the females give birth to 2 – 57 young. The average number of snakes a female gives birth to is smaller in coastal populations compared to inland populations.
As extreme weather conditions are expected to increase, the response of wildlife to these phenomena becomes increasingly important. A study on the southern water snake showed that the species was susceptible to drought conditions, causing the species to drop significantly in site occupancy (up to 30% reduction). It has been suggested that the species simply recognizes an oncoming drought, and emigrates to more stable aquatic habitats, yet if that is the case, the mortality is believed to be high, since very few snakes seem to migrate back. However, the species is resilient, as they are quick to repopulate an area when the water levels return.
