Louisiana is a hot and humid state containing diverse aquatic habitats, from mangroves and salt marshes to beautiful coastal wetlands and mud flats. An abundance of fish and small mammals combined with a long warm season provides perfect conditions for many southeastern reptiles. There are over 50 snake species in Louisiana, several containing a region of environment-specific subspecies. Snakes are an essential part of natural communities in Louisiana because they control fish and rodent populations. They are also an important food source for predatory fish, mammals, and birds.
While Louisiana is known for its wetlands and swamps, there are many more types of ecosystems to be found here that provide homes for a diverse array of wildlife. Six broad ecoregions or regions with distinct geography and environmental factors can be found in Louisiana. Generally, they are characterized as being relatively flat with rolling hills or plains with different soil types and plant communities found in each one. Wetlands, bottomland hardwood forests, shortleaf pine, endangered longleaf pine forests, prairies, coastal regions, and upland regions make up most of Louisiana’s habitats.
Louisiana Aquatic Snakes
1) Common watersnake
- Scientific name: Nerodia sipedon
- Meaning of scientific name: “Neros” refers to flowing liquid and “sipendon” refers to a serpent whose bite causes mortification.
- Family: Colubridae
- Subfamily: Natricinae
- Other names: Northern watersnake
- Average adult length: 25 to 40 in (64 to 102 cm)
- Maximum adult length: 60 in (152 cm)
- Threatened status: Least Concern
The common watersnake is abundant in the eastern half of the United States. The midland watersnake, the subspecies N. s. pleuralis, is the only common watersnake found in Louisiana. They inhabit the Southeastern Plains and Mississippi Valley Loess ecoregions or the northern half of the “tip” of Louisiana’s “boot”. Young common watersnakes bear a rusty coloration with dark vertical bands running down their bodies. However, the bands on older snakes may fade. The belly of this snake has an attractive mosaic pattern that helps camouflage it from predatory fish while swimming through the water. Fish and amphibians are their primary food source. They also eat crayfish, mice, large insects, and other prey types. This diet is typical of watersnakes.
Watersnakes lack the heat-seeking pits found in venomous vipers. Instead of venom, watersnakes employ other defensive strategies like flattening their heads to confuse predators into thinking they are dangerous and releasing “musk”, a foul liquid.
Watersnakes are viviparous, meaning that they give birth to live young. Common watersnakes expect an average of 15 – 20 precocious young from each litter, and their breeding season extends from April to June.
2) Southern watersnake
- Scientific name: Nerodia fasciata
- Meaning of scientific name: “Neros” refers to flowing liquid and “fasciata” means banded or striped.
- Family: Colubridae
- Subfamily: Natricinae
- Other names: Banded watersnake
- Average adult length: 25 to 40 in (64 to 102 cm)
- Maximum adult length: 60 in (152 cm)
- Threatened status: Least Concern
This species can be found along the coast of the United States from Texas to Florida. The southern watersnake’s range extends northward along the Mississippi River in Louisiana. The southern watersnake can be distinguished from other species in the genus Nerodia by the presence of a line running from the eye to the edge of the jawline. This black line is a unique characteristic of this species. Southern watersnakes are also smaller than the northern watersnake and, where their ranges overlap, readily hybridize with them. Southern watersnakes have belly camouflage like common watersnakes, although they do not have the distinct banding seen in common watersnakes.
Southern watersnakes are diurnal and are most active during the day, where they can be found in freshwater lakes, ponds, marshes, and swamps. This species does not tolerate high-salinity environments and avoids salt marshes and estuaries. During the day, they predate upon fish, amphibians, crayfish, large insects, turtles, and small birds. Smaller individuals tend to target smaller fish species, while adults will target larger fish and other listed prey items. Herons, kingsnakes, and alligators are common predators of all watersnakes. This species will breed once from July to October. Gravid females will produce an average of 20 offspring about four to five months later.
3) Diamond-backed watersnake
- Scientific name: Nerodia rhombifer
- Meaning of scientific name: “Neros” refers to flowing liquid and “rhombifer” means to bear rhombuses (diamond-like shapes).
- Family: Colubridae
- Subfamily: Natricinae
- Other names: Diamondback watersnake
- Average adult length: 35 to 47 in (89 to 119 cm)
- Maximum adult length: 62 in (157 cm)
- Threatened status: Least Concern
Given the diamond-like pattern along its back and its aggressive temperament when cornered, the diamond-backed watersnake is often mistaken for the venomous cottonmouth and diamondback rattlesnake. Though the name is reminiscent of the diamondback rattlesnake, the diamond-backed watersnake is unrelated and non-venomous. The pattern on this species is dark brown with a black web-like pattern that darkens in adult snakes along the dorsal surface. They are abundant throughout Louisiana and can be found in all Louisiana parishes. Unfortunately, some populations in the United States are threatened by habitat loss and pesticide-related mortality.
Permanent, slow-moving streams, lakes, or swamps are the ideal habitat for this species. Here, they predate upon primarily small fish and amphibians, an exclusive diet that makes this species’ musk particularly smelly. They are typically an active diurnal hunter, although they will hunt at night if daytime temperatures are too warm. This species breeds in the spring and females give birth to between 13 and 62 pups in the late summer or early fall.
4) Red-bellied watersnake
- Scientific name: Nerodia erythrogaster
- Meaning of scientific name: “Neros” refers to flowing liquid and “erythrogaster” means “red belly”.
- Family: Colubridae
- Subfamily: Natricinae
- Other names: Redbelly, yellowbelly, copperbelly, blotched watersnake, plain-bellied watersnake
- Average adult length: 30 to 48 in (76 to 122 cm)
- Maximum adult length: 62 in (157 cm)
- Threatened status: Of Least Concern but threatened in some parts of its range. The subspecies N. e. neglecta is threatened.
This watersnake species can be found in most Louisiana parishes except the West Carroll, Jackson, Winn, and Red River parishes. This semi-aquatic colubrid is primarily brown with a yellow belly and black striping along the rust-colored ventral surface between scale plates. While similar in appearance to the southern watersnake, the red underbelly of this species is a dead giveaway. They can be found near water bodies in forested areas like cypress swamps and drainage ditches, but during hotter, humid weather, they tend to avoid aquatic habitats and are therefore considered more terrestrial than other watersnakes.
Sexual maturity in red-bellied watersnakes occurs around 3 to 4 years of age. The mating season lasts from April to June, followed by a 4 – 5 month gestation period, after which plain-bellied watersnakes will give birth from August to October. Females can give birth to between 2 and 55 pups per litter. Reportedly, this species is capable of parthenogenesis.
5) Mississippi green watersnake
- Scientific name: Nerodia cyclopion
- Meaning of scientific name: “Neros” refers to flowing liquid and “cyclopion” is derived from the Greek word “Kyklops”, which refers to a mythical, one-eyed giant.
- Family: Colubridae
- Subfamily: Natricinae
- Other names: None
- Average adult length: 30 to 40 in (76 to 102 cm)
- Maximum adult length: 55 in (140 cm)
- Threatened status: Not Endangered via the U.S. Endangered Species Act, but they are threatened at the state level in Florida, Alabama, Tennessee, Michigan, Illinois, and Arkansas.
The Mississippi green watersnake was initially described in New Orleans. It is an inconspicuous olive-brown snake with minimal markings aside from yellow spots along its belly. It can be easily distinguished from other watersnakes due to a lack of striping or banding along its body. As the common name suggests, it occasionally appears “green” in color.
Like the mud snake, the Mississippi green watersnake prefers forested areas with slow-moving or calm streams, ponds, and lakes. Sometimes they will inhabit brackish water, although they are not found in saltwater habitats. Their diet primarily includes fish of the genus Gambusia. However, like most other watersnakes, they are known to predate upon crayfish and small frogs occasionally. Additionally, this species tends to exhibit more aggressive defensive behaviors than other watersnakes when threatened.
The breeding season for this species occurs in April and May. In the late summer or early fall, females will give birth to 8 to 34 pups, but the average tends to be closer to 10 to 20 pups.
6) Salt marsh watersnake
- Scientific name: Nerodia clarkii
- Meaning of scientific name: “Neros” refers to flowing liquid and “clarkii” refers to the American surveyor and naturalist John Henry Clark.
- Family: Colubridae
- Subfamily: Natricinae
- Other names: Salt marsh snake
- Average adult length: 15 to 30 in (38 to 76 cm)
- Maximum adult length: 36 in (91 cm)
- Threatened status: As a species, they are of Least Concern, but the subspecies N. c. taeniata, the Atlantic saltmarsh watersnake, is listed as Threatened.
The salt marsh watersnake has a more restricted range than other individuals in this genus, occurring only in Texas, Louisiana, Mississippi, Alabama, and Florida. In Louisiana, this snake only occurs in the southern parishes along the Gulf of Mexico. Additionally, only the subspecies N. c. clarkii can be found in Louisiana. This snake has markings like a garter snake but with the thicker body of a watersnake. They do not possess any bar patterns and have long stripes running down the sides of their dark-brown bodies. However, some individuals may be entirely black, so humans frequently confuse them with cottonmouths.
Salt marsh watersnakes specialize in tidal marshes, mud flats, and mangroves. They are one of the few watersnakes that can tolerate high salinity, despite lacking salt glands that are typical of marine snakes. They are nocturnal hunters with a diet consisting of fish, frogs, and crabs.
While not considered threatened as a species, salt marsh watersnake populations are declining due to habitat loss. Habitat loss factors include development, pollution, and shoreline alteration via dredging and diking.
7) Mud snake
- Scientific name: Farancia abacura
- Meaning of scientific name: “Abacura” comes from the Latin word “abacus“, which means “counting board”.
- Family: Colubridae
- Subfamily: Dipsadinae
- Other names: Eastern mud snake, horn snake, hoop snake
- Average adult length: 40 to 54 in (102 to 137 cm)
- Maximum adult length: 81 in (206 cm)
- Threatened status: Least Concern
This attractive, non-venomous snake is visually stunning with a solid black dorsal surface and a checkered red or pink belly. Because of this striking color pattern, mud snakes are often kept as pets. However, since their preferred prey is amphibians, they are challenging to keep alive in captivity. When threatened, they will coil around themselves, flashing the red belly as a false warning to any potential predators. Additionally, young mud snakes will attempt to stab predators with a tail spike located on the tip of their tail. Mud snake predators include snakes, wading shorebirds, and snake-eating mammals. Additionally, they are host to a suite of parasite species.
Mud snakes love various aquatic, freshwater habitats with slower-moving water and abundant submerged vegetation. Examples include cypress swamps to brackish estuaries and tidal creeks. Here, they will spend most of their time in the water or, if found on land, bury themselves in the mud.
The mud snake is one of the largest species on this list, capable of reaching lengths of up to six feet. They reach sexual maturity at about two and a half years, and the breeding season extends from July to September. This species is oviparous, meaning that they lay eggs. These eggs take about 56 days to develop, and then another 60 days must pass before they hatch. On average, a gravid female will lay between 20 and 30 eggs, however, a single clutch has reported as many as 104 eggs. Females coil around the eggs until they hatch, but it is unknown why they do this because they are not defensive of their eggs if disturbed.
8) Cottonmouth
- Scientific name: Agkistrodon piscivorus
- Meaning of scientific name: “Agkistrodon” refers to their hooked fangs and “piscivorus” means “fish-eater”.
- Family: Viperidae
- Subfamily: Crotalinae
- Other names: Water moccasin
- Average adult length: 24 to 48 in (61 to 122 cm)
- Maximum adult length: 70 in (178 cm)
- Threatened status: Least Concern
The cottonmouth is common throughout the United States’ southern wetlands and can be found from Texas to Virginia. It is the only venomous aquatic snake in Louisiana, and their common name is derived from the white interior of their mouths. While often confused with non-venomous watersnakes, it can be reliably distinguished from other fish species by looking for heat pits between the eye and the nostril. Cottonmouths also have vertical pupils, while watersnakes have round pupils. Cottonmouth eyes are also protected by ridges that give them an “angry” look.
The genus name Agkistrodon refers to their recurved fangs, which allow them to grip onto slippery prey. These hollow fangs deliver hemotoxic venom into prey items. As with most aquatic snakes, fish make up the bulk of this species’ diet, but they are known to predate upon amphibians, small mammals, and invertebrates.
Females reproduce once every two to three years. Mating occurs in the spring and the fall. Like watersnakes, the cottonmouth gives birth to live young. The adult remains near bodies of water in their home ranges. However, young cottonmouths are known to travel long distances to avoid competition with their parents and siblings. In addition, unlike many other semi-aquatic snakes in Louisiana, the adult male of this species is larger than the female.
9) Graham’s crayfish snake
- Scientific name: Regina grahamii
- Meaning of scientific name: “Regina” is Latin for “queen”, and the species epithet “grahamii” is designated for Lt. Col. James Duncan Graham. He collected the specimen used to describe the species.
- Family: Colubridae
- Subfamily: Natricinae
- Other names: Arkansas water snake, Graham’s leather snake, Graham’s queen snake, Graham’s snake, Graham’s water snake, prairie water adder, prairie water snake, striped moccasin
- Average adult length: 18 to 28 in (46 to 71 cm)
- Maximum adult length: 47 in (119 cm)
- Threatened status: Least Concern
One of the more reclusive species on this list, the Graham’s crayfish snake is not as common as watersnakes or cottonmouths. The range for this species extends as far west as Texas, eastward to Mississippi, and northward to Iowa. It inhabits forested lakes, rivers, wetlands, marshes, and at higher elevations, rocky pools and streams where it specializes in eating recently molted crayfish. Given this specialized diet, a habitat including a suitable water source is an absolute must for this species. Unfortunately, crayfish snake populations are declining in some areas due to habitat loss and fragmentation and declines in crayfish abundance.
The breeding season occurs during April or May, and females will give birth between July and September to litters of 6 – 39 baby snakes. Like other watersnakes, they are typically nocturnal when the weather is hot and are active during the day when temperatures are milder.
10) Crayfish snake
- Scientific name: Liodytes rigida
- Meaning of scientific name: “Liodytes” means smooth diver and “rigida” means stiff.
- Family: Colubridae
- Subfamily: Natricinae
- Other names: Glossy crayfish snake, glossy swampsnake, glossy watersnake, striped watersnake
- Average adult length: 14 to 24 in (36 to 61 cm)
- Maximum adult length: 31 in (79 cm)
- Threatened status: Least Concern
Crayfish snakes are dark brown on their dorsal surface with a lighter, caramel-colored underbelly. Historically, the classification of this species was hotly debated, and this species is often confused with Graham’s crayfish snake. The two species are currently placed into different genera. Two subspecies, the Gulf crayfish snake (L. r. sinicola) and the Delta crayfish snake (L. r. deltae), are present in Louisiana. The Gulf subspecies occurs mainly in the western part of Louisiana. In contrast, the Delta subspecies can be found east of the Atchafalaya Basin. As a whole, this species is present in the southern United States from Texas to Virginia and is reportedly uncommon. However, it is a cryptic species that is difficult to find, so it may be more common.
Like Graham’s crayfish snake, their primary prey item is crayfish, but they are not crayfish specialists. Young crayfish snakes will eat other invertebrates, fish, and amphibians like other colubrid species. While most snakes consume their prey headfirst, crayfish snakes will consume their prey tail-first to avoid injury from crayfish claws.
11) Common garter snake
- Scientific name: Thamnophis sirtalis
- Meaning of scientific name: “Thamnophis” is a combination of “thamnos“, meaning shrub or bush, and “ophio“, referring to a serpent.
- Family: Colubridae
- Subfamily: Natricinae
- Average adult length: 8 to 36 in (20 to 91 cm)
- Maximum adult length: 50 in (127 cm)
- Threatened status: Least Concern
The common garter snake is more widespread than the western ribbon snake and common throughout their range. The classification of garter snakes and closely related species is messy, and this species contains many subspecies. The easiest way to distinguish a garter snake from a ribbon snake is by looking at the lip scales. In garter snakes, the lips have dark marks on the edges, and ribbon snakes are without these marks. Ribbon snakes also have longer tails compared to garter snakes.
The common garter snake can be found in riparian habitats, wetlands, bogs, and urban areas. They are less aquatic than other snakes on this list except where they are confined to riparian areas by mountains, roads, or other barriers. Their diet consists of earthworms, amphibians, and fish.
Interestingly, some common garter snakes hibernate almost entirely submerged in water. The advantage to this hibernation strategy is that they do not lose as much water as a snake hibernating in a dry den. Additionally, they have evolved to have meager metabolic rates at low temperatures and therefore do not require as much oxygen. Sexual maturity occurs at 1.5 – 2 years of age, and they mate in the spring. Females will give birth to approximately 13 to 26 pups in July or August. However, another source suggests the range is 10 to 40 pups or as many as 4 to 80 pups.
12) Western ribbon snake
- Scientific name: Thamnophis proximus
- Meaning of scientific name: “Thamnophis” is a combination of “thamnos“, meaning shrub or bush, and “ophio“, referring to a serpent. “Proximus” means nearest and refers to its relationship with the common garter snake.
- Family: Colubridae
- Subfamily: Natricinae
- Average adult length: 8 to 36 in (20 to 91 cm)
- Maximum adult length: 50 in (127 cm)
- Threatened status: Least Concern
The Gulf Coast ribbon snake (T. p. orarius) is the only western ribbon snake subspecies in Louisiana. This species was initially considered a subspecies of the common garter snake and was distinguished as a unique species in 1963. This species predates upon amphibians, fish, small mammals, eggs, and crustaceans, although they specialize in amphibians. When hunting frogs, it displays a unique behavior: flushing frogs from the water using head thrusts. The snake quickly detects disturbed frogs and eats them. They are reclusive and disappear into the water or nearby plants to hide if disturbed. Predatory mammals and birds hunt them. It can lose its tail if captured, which is unusually long for a snake in this group.
They prefer high ground cover in forested riparian areas with shallow water. They tolerate a range of temperatures and can be found from spring to the end of summer when temperatures are between 39° and 107° F (4° to 42° C).
Western ribbon snakes reach reproductive maturity between 12 and 15 months, and breeding occurs during the spring but varies by location. A female western ribbon snake can expect between 4 and 27 pups between July and September.
