B
Species Profile

Brown Water Snake

Nerodia taxispilota

Big river snake, not a cottonmouth
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Brown Water Snake Distribution

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Endemic Species
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brown watersnake, nerodia taxispilota

At a Glance

Wild Species
Diet Carnivore
Activity Diurnal+
Lifespan 7 years
Weight 2.5 lbs
Status Least Concern
Did You Know?

It's often cited as the largest North American watersnake: reported maximum total length ~177.8 cm (Ernst & Ernst, 2003); many adults are much smaller (commonly <150 cm).

Scientific Classification

A large, nonvenomous, semi-aquatic colubrid snake of the southeastern United States, commonly found in and around freshwater bodies. Frequently mistaken for venomous cottonmouths due to its robust build and defensive behavior.

Kingdom
Animalia
Phylum
Chordata
Class
Reptilia
Order
Squamata
Family
Colubridae
Genus
Nerodia
Species
Nerodia taxispilota

Distinguishing Features

  • Heavy-bodied watersnake with brown ground color and darker square/rectangular blotches (often appearing as a checkered pattern) along the back and sides
  • Strongly keeled scales giving a rough texture
  • Head not distinctly triangular (though it may flatten when threatened) and pupils are round
  • Semi-aquatic behavior: frequently seen swimming or basking above water; strong musky odor when handled

Physical Measurements

Males and females differ in size

Length
3 ft 3 in (2 ft 4 in – 4 ft 7 in)
4 ft 1 in (2 ft 11 in – 5 ft 10 in)
Weight
1 lbs (0 lbs – 2 lbs)
2 lbs (1 lbs – 6 lbs)
Tail Length
9 in (6 in – 1 ft 1 in)
9 in (6 in – 11 in)
Top Speed
2 mph
Top speed not measured

Appearance

Primary Colors
Secondary Colors
Skin Type Keratinized scales; dorsal scales strongly keeled (rough-textured) typical of Nerodia; semi-aquatic skin/scales often appear glossy when wet. Commonly reported midbody dorsal scale rows: 25-29 (keeled).
Distinctive Features
  • Nonvenomous natricine watersnake (genus Nerodia); lacks heat-sensing facial pits and lacks the large hollow fangs of pit vipers.
  • Robust, heavy-bodied build with a relatively broad head/neck-frequently leads to confusion with cottonmouths (Agkistrodon piscivorus).
  • Key visual separation from cottonmouths: round pupils (in normal light) and no facial pit; also often shows vertical dark bars/marking on the upper/lower labial (lip) scales that cottonmouths typically lack.
  • Defensive behavior: commonly flattens the head/neck, may gape, strike repeatedly, and releases strong-smelling musk; this defensive display contributes to misidentification as a dangerous species.
  • Strongly semi-aquatic appearance: frequently seen basking on branches/logs over freshwater (rivers, swamps, lakes) and dropping into the water when disturbed; excellent swimmer.
  • Adult total length commonly ~76-152 cm; documented maximums in field references are ~175 cm (making it one of the largest Nerodia).
  • Typical adult mass is variable with sex and season; large females may appear notably thick-bodied when gravid.
  • Longevity: precise wild lifespan estimates are limited; captive longevity reported for Nerodia watersnakes is commonly on the order of ~10-12+ years (varies by husbandry and source).

Sexual Dimorphism

Sexual size dimorphism is typical: females average larger and heavier-bodied than males; males tend to have proportionally longer tails (hemipenes) and a more tapering posterior body profile.

  • Generally smaller overall body size than females at maturity.
  • Proportionally longer tail (posterior to the cloaca) and more gradual tapering body-to-tail transition.
  • Often slimmer-bodied outside the breeding season.
  • Larger average total length and noticeably greater girth/heavier body mass, especially when gravid.
  • Shorter tail relative to body length compared with males.
  • May appear extremely robust in late gestation due to live-bearing reproduction (typical of Nerodia).

Did You Know?

It's often cited as the largest North American watersnake: reported maximum total length ~177.8 cm (Ernst & Ernst, 2003); many adults are much smaller (commonly <150 cm).

It is nonvenomous (no fangs/venom glands like pit vipers) but can bite defensively and release a strong-smelling musk-one reason people think it's "mean."

Unlike cottonmouths (Agkistrodon piscivorus), it has no heat-sensing facial pits and typically shows round pupils (though pupil shape can be hard to see in the field).

A frequent posture is "periscope" swimming: head held up while the body moves just below the surface-useful for scanning and breathing while traveling.

It commonly basks on branches or logs over water; when startled it may drop straight into the water rather than flee over land.

Reproduction is live-bearing (not egg-laying): litters reported from roughly 10 to >50 young in large females (range reported in standard herpetology references such as Ernst & Ernst, 2003).

Its species name taxispilota is often interpreted as referring to "yew-like/dark spotting," reflecting the dark, square-ish blotches that give a checkered look on many individuals.

Unique Adaptations

  • Strongly keeled scales and robust body: improves traction on slippery banks and vegetation and helps with powerful swimming.
  • Nostrils positioned high on the snout with valving behavior: helps keep water out while swimming at the surface.
  • High tolerance for aquatic prey handling: quick strikes and firm jaw grip allow it to subdue slippery fish and amphibians without constriction.
  • Cryptic blotched/checkered dorsal pattern: breaks up the snake's outline in dappled river light and among roots, leaf litter, and tannin-stained water.
  • Semi-arboreal flexibility: despite being "aquatic," it climbs well and uses overhanging structure for basking, ambush, and rapid escape into water.

Interesting Behaviors

  • Defensive escalation: when cornered it may flatten the body, gape, strike repeatedly, and musk-classic "watersnake bravado" that increases cottonmouth confusion.
  • Branch-basking and "drop escape": frequently rests on overhanging vegetation; if disturbed it may fall into the water and disappear with rapid swimming.
  • Active foraging along edges: hunts by cruising shorelines and structure (roots, snag piles, rocks) for fish and amphibians, often striking quickly and holding prey.
  • Seasonal surface activity: most often encountered in warm months near freshwater; in cooler periods it reduces activity and uses sheltered retreats near water.
  • Live-bearing timing: mating typically occurs in spring; young are usually born late summer to early fall in much of the range (timing summarized in regional life-history accounts, e.g., Ernst & Ernst, 2003).
  • Aquatic vigilance: when approached on land it often heads for water; when approached in water it may stand its ground and display rather than immediately flee.

Cultural Significance

Brown Watersnake (Nerodia taxispilota) is often mistaken for cottonmouths ("water moccasins") and killed, though harmless and helpful, eating fish and frogs. Common in rivers and swamps and familiar to anglers, paddlers, and people who live near water.

Myths & Legends

Southeastern 'water moccasin' tales often blame large watersnakes like the Brown Watersnake (Nerodia taxispilota), as Nerodia often strike again and again when cornered, so stories of snakes chasing boats or people persist.

Cherokee stories about the Uktena, a horned river serpent, shape how people imagine big snakes in southeastern rivers, even if they are not about Brown Watersnakes (Nerodia taxispilota).

In Muscogee (Creek) and broader Southeastern stories of the Horned or Great Serpent, water snakes are powerful spirits tied to deep pools and river bends, shaping fear and respect for big freshwater snakes.

In Appalachian and Southern folk belief, seeing a big river snake like the Brown Watersnake (Nerodia taxispilota) at a fishing spot or crossing is an omen about weather, luck, or safety.

Conservation Status

LC Least Concern

Widespread and abundant in the wild.

Population Stable

Life Cycle

Birth 30 hatchlings
Lifespan 7 years

Lifespan

In the Wild
4–12 years
In Captivity
10–20 years

Reproduction

Mating System Polygynandry
Social Structure Solitary
Breeding Pattern Transient
Fertilization Internal Fertilization
Birth Type Internal_fertilization

Brown Watersnake (Nerodia taxispilota) are viviparous natricine snakes, usually solitary with no lasting pair bonds. Mating is polygynandrous: both sexes have multiple partners in spring. Females give live young in late summer and provide no care.

Behavior & Ecology

Social Den Group: 1
Activity Diurnal, Crepuscular, Nocturnal
Diet Carnivore Fish-particularly common, readily captured freshwater fishes (frequently including catfishes and sunfishes in many populations).
Seasonal Hibernates

Temperament

Generally non-territorial and avoids confrontation when undisturbed; social intolerance is low because conspecifics are typically encountered only incidentally at shared basking or refuge sites (Ernst & Ernst, 2003).
Frequently defensive when approached/handled: may flatten head/neck, coil, strike repeatedly, bite, and release cloacal musk/feces-behavior that contributes to misidentification as cottonmouths (Gibbons & Dorcas, 2004).
Brown Watersnake (Nerodia taxispilota) are mostly solitary hunters along freshwater edges, using ambush or active hunting. They are more active by day when cool, and at dusk or night when hot.

Communication

Hissing Defensive exhalation; common when threatened/handled; Ernst & Ernst, 2003
Chemical communication via tongue-flicking and vomeronasal Jacobson's) organ; used for prey assessment and mate tracking (pheromonal trails), as in other Nerodia (Ernst & Ernst, 2003
Tactile signaling during courtship/mating Body alignment, rubbing/arching; temporary physical association) (Ernst & Ernst, 2003
Visual/threat displays: body inflation/flattening, S-coiling, striking posture; serves as deterrence rather than intraspecific dominance signaling Gibbons & Dorcas, 2004
Olfactory deterrent: cloacal musk discharge Often with feces) as antipredator signaling (Gibbons & Dorcas, 2004
Mechanosensory cues: sensitivity to substrate and water vibrations important for detecting prey/predators and may incidentally mediate spacing/avoidance among conspecifics in shared microhabitats General snake sensory ecology; summarized in Ernst & Ernst, 2003

Habitat

Biomes:
Freshwater Wetland Temperate Forest
Terrain:
Riverine Coastal Plains Valley Muddy
Elevation: Up to 1968 ft 6 in

Ecological Role

Aquatic-to-riparian mesopredator in southeastern U.S. freshwater systems, specializing on fish and occasionally amphibians/crayfish.

Helps regulate local fish (and sometimes amphibian) populations through predation Links aquatic and terrestrial food webs by moving aquatic biomass/nutrients into riparian habitats (via digestion, feces, and as prey for higher predators) Can serve as a bioindicator of aquatic habitat quality and prey-community structure because its diet reflects local fish availability

Diet Details

Main Prey:

Human Interaction

Domestication Status

Wild

Brown Watersnake (Nerodia taxispilota) is a wild, non-domesticated North American snake with no history of selective breeding. Humans meet it by water or kill it after mistaking it for cottonmouths (Agkistrodon). It is strongly aquatic and defensive—flattening the body, gaping, striking, and releasing musk. Adults reach about 76–178 cm; females are larger.

Danger Level

Low
  • Nonvenomous bite: can be painful and may bleed due to recurved teeth; risk increases when handled or harassed.
  • Bacterial infection risk from any reptile bite/handling (including Salmonella exposure from contact with the animal or contaminated water).
  • Defensive musk/feces discharge when captured can cause minor eye/skin irritation and strong odor.
  • Indirect risk: frequent misidentification as venomous cottonmouths can lead to panic responses, unsafe attempts to kill/remove snakes, and accidental injuries.

As a Pet

Not Suitable as Pet

Legality: Laws vary by state and local area. The Brown Watersnake (Nerodia taxispilota) is a native southeastern U.S. wild snake, so permits, limits, or bans on keeping it often apply. Captive-bred ones may also be regulated. Check local rules.

Care Level: Experienced

Purchase Cost: $50 - $200
Lifetime Cost: $1,500 - $4,500

Economic Value

Uses:
Ecosystem services (predation on fish/amphibians; role in freshwater food webs) Education/outreach (nature centers; live animal programs where legally permitted) Scientific research (ecology, wetland/freshwater systems, trophic dynamics)
Products:
  • No conventional commercial products; not a standard food/leather species in the U.S. legal market. Limited/rare niche demand in the pet trade (mostly non-commercial, highly regulated if native-collected).

Relationships

Related Species 8

Banded Watersnake
Banded Watersnake Nerodia fasciata Shared Genus
Northern Watersnake
Northern Watersnake Nerodia sipedon Shared Genus
Plain-bellied Watersnake Nerodia erythrogaster Shared Genus
Diamondback watersnake Nerodia rhombifer Shared Genus
Green Watersnake Nerodia cyclopion Shared Genus
Common garter snake
Common garter snake Thamnophis sirtalis Shared Family
Eastern Ratsnake
Eastern Ratsnake Pantherophis alleghaniensis Shared Family
Eastern Kingsnake Lampropeltis getula getula Shared Family

Ecological Equivalents 5

Animals that fill a similar ecological role in their ecosystem

Cottonmouth
Cottonmouth Agkistrodon piscivorus Co-occurs in the same southeastern freshwater habitats (swamps, rivers, ponds) and can resemble cottonmouths. Cottonmouths are venomous and consume more vertebrate prey, whereas brown watersnakes are nonvenomous and feed mainly on fish and frogs.
Queen Snake
Queen Snake Regina septemvittata Semi-aquatic natricine colubrid that uses similar shoreline and stream-edge microhabitats and forages by actively searching in and near water. Ecological contrast: Queen Snakes are specialized crayfish predators, whereas Brown Watersnakes are broader generalists that commonly eat fish and amphibians.
Glossy Crayfish Snake Regina rigida Shares southeastern aquatic habitats and an active, shoreline-oriented hunting strategy. Occupies a similar overall niche as a nonvenomous, semi-aquatic colubrid but differs in diet specialization—primarily crayfish versus the more fish- and amphibian-focused diet typical of Brown Watersnakes.
Eastern Mud Snake
Eastern Mud Snake Farancia abacura Large, strongly aquatic snake that uses swamps and slow-water systems in the southeastern U.S. Like brown watersnakes, it is nonvenomous and semi-aquatic to aquatic; however, mud snakes are more fossorial and aquatic and specialize heavily on eel-like prey, notably siren salamanders and amphiumas.
Common Snapping Turtle
Common Snapping Turtle Chelydra serpentina Although not a snake, it frequently co-occurs in similar freshwater habitats. It is an opportunistic aquatic predator that overlaps in prey (fish and amphibians) and uses the same shallow-water and shoreline zones.

Brown water snakes are commonly seen with the spines of catfish they’ve eaten sticking out of their sides!

Brown water snakes are aquatic snakes from North America that feed primarily on fish. Many times a brown water snake has been seen with the spines of catfish they’ve eaten sticking out of their sides! They typically recover from these injuries. These snakes are nonvenomous and not aggressive, but they can be mistaken for the venomous cottonmouth.

4 Incredible Brown Water Snake Facts!

  • They take on dangerous prey — catfish that have sharp spines. These spines may pierce the snake after the fish is swallowed, but the snake usually survives and recovers.
  • A brown water snake may fall out of a tree into the water when startled.
  • They hunt by scent rather than by visually tracking movement.
  • These snakes release a smelly musk when frightened.
Channel catfish

Brown water snakes enjoy eating catfish despite their sharp spikes.

Scientific Name

The brown water snake, also spelled watersnake, has the scientific name Nerodia taxispilota. Nerodia is from the Greek neros translating to “flowing” or “liquid” and dia meaning “through,” while taxis refers to “arrangement” and spilos being “spot.”

It was first described scientifically in 1842 by the American zoologist and herpetologist John Holbrook, who then called the species Tropidonotus taxispilotus, assigning it to a different genus. In 1889, zoologist Edward Cope gave it the identification Natrix taxispilota. The brown water snake received its current scientific identification in 1991. It is part of the family Colubridae and class Reptilia.

Other common names for the brown water snake include water rattle, the southern water snake, the pied water snake, the greater water snake, the water-pilot, the aspic, and the false moccasin.

Sometimes, the common name “brown water snake” is also applied to the species Lycodonomorphus rufulus. These two species should not be confused in identification, as L. rufulus is native to South Africa.

The brown water snake’s scientific name is Nerodia taxispilota.

Evolution and Origins

The brown water snake belongs to the Colubridae family, which is the largest of the snake families and has more than 240 genera, including the garter snake, Indian rat snakes, and Asian vine snakes. The earliest colubrid species can be traced back to the Oligocene epoch, 33.9 million to 23 million years ago. Fossils from Adams County in Washington indicate that colubrids were present in the Pliocene (Blancan).

Thamnophis brachystoma, the shorthead garter snake or short-headed gartersnake

The brown water snake belongs to the same family as the garter snake, above.

Appearance

This snake has a thick, heavy body that is light brown with darker brown rectangular patches. The patches on the back are larger than those on the sides, and the back and side patches are usually not connected. The brown water snake has a broad, triangle-shaped head with a distinctly narrower neck for its size. For this reason, it is sometimes misidentified as a venomous snake.

Brown water snakes have keeled scales. This means that the scales are not smooth but have a ridge down the center. It has more scales than any other water snake on the continent — 27 to 33 rows of dorsal scales. It also has two to four anterior temporal scales behind the eyes, whereas most other snakes have only one.

Brown water snakes are typically 3.5 to five feet in length. The record size is nearly six feet in length at 69 inches.

Baby snakes are smaller than adult reptiles but the baby’s colors are the same as the adults’ colors. This makes the identification of the baby easier.

How to Identify a brown water snake:

  • Brown base color with darker brown rectangular patches
  • Large patches on the back, and smaller patches on the sides
  • Heavy body with a broad, triangular head
  • Eyes set toward the top of the head
  • Yellow or cream-colored belly.

The brown water snake has a triangular head, with their eyes being set toward the top.

Brown Water Snake vs Cottonmouth

Cottonmouths and brown water snakes are often confused because of their similar range, habitat location, colors, body, and head shape.

In the American South, it is often repeated that venomous snakes have triangle-shaped heads. These are facts of the rattlesnakes, cottonmouths, and copperheads that live in that location, but it is also true of nonvenomous species like the brown water snake. Sadly, this results in people killing water snakes, thinking they are dangerous.

There are a few subtle differences to look for to tell these snakes apart. Cottonmouths are pit vipers; they have heat-sensing pits between the eye and nostril. Water snakes lack these pits.

Additionally, cottonmouths have a distinctive bright white coloration inside their mouths — hence the name. The white inner lining of the mouth can be seen when the snake is agitated and poised to strike. A brown water snake has a dark-colored mouth.

The pupils of the reptile’s eyes are also slightly different, with the watersnake’s being rounder.

The cottonmouth is confused for the brown water snake but can be identified by its bright white mouth.

Behavior

These snakes are shy and are likely to flee if approached by a human. They often rest on tree branches overhanging a body of water. They can make a quick getaway by falling into the water if disturbed.

If cornered or captured, a brown water snake will coil, hiss, strike, and attempt to bite. They also release a smelly musk when frightened.

Humans are a much larger threat to these predators than they are to us. Each year, many of these snakes are needlessly killed because they are mistaken for venomous water snakes. Some are killed simply because some people are afraid of all snakes, regardless of the species.

Venom: How Dangerous Are Brown Water Snakes?

Brown water snakes have no venom. When threatened, they are likely to flee. However, these snakes are predators and will bite if cornered. Though not venomous, snake bites can become infected and require medical care.

The common watersnake (Nerodia sipedon)

Brown water snakes are not venomous.

Habitat

Brown water snakes are endemic or native to southeastern North America. This includes the states of Alabama, Florida, Georgia, Louisiana, Mississippi, Missouri, North Carolina, South Carolina, and Virginia.

The brown water snake is typically found at elevations ranging from sea level to 500 feet. Their habitat and location consist of streams, swamps, and other wet areas. They must have an aquatic habitat since their primary food source is a diet of fish.

Brown water snakes are native to southeastern North America.

Diet

Brown water snakes eat fish; catfish are their favorite prey. Sometimes they will also eat amphibians such as frogs, invertebrates, or small mammals.

Captive water snakes should be fed a diet of live fish placed in the aquatic portion of their aquarium. Since water snakes hunt by smell and not by sight, they are unlikely to bite your fingers, mistaking them for food.

North American green frog sitting in marsh pond.

Brown water snakes will sometimes eat frogs.

Predators and Threats

Natural predators of brown water snakes include American alligators, birds of prey, and raccoons. Some larger snakes such as cottonmouths — which are often confused with brown water snakes — may also prey on these snakes. Humans are a threat to this species especially if they misidentify these snakes are cottonmouths.

alligator with its mouth hanging open

The American alligator is one of the brown water snake’s predators.

Population and Conservation

The brown water snake is common or of Least Concern throughout its habitat. It is not protected in much of its range, but there are areas in which killing the brown water snake is illegal, including the state of Georgia.

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Sources

  1. Wikipedia / Accessed January 23, 2022
  2. Savannah River Ecology Laboratory: UGA / Accessed January 23, 2022
Catherine Gin

About the Author

Catherine Gin

Catherine Gin has more than 15 years of experience working as an editor for digital, print and social media. She grew up in Australia with an alphabet of interesting animals, from echidnas and funnel-web spiders to kookaburras and quokkas, as well as beautiful native plants including bottlebrushes and gum trees. Being based in the U.S. for a decade has expanded Catherine's knowledge of flora and fauna, and she and her husband hope to have a hobby farm and vegetable garden in future.

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Brown Water Snake FAQs (Frequently Asked Questions)

No, brown water snakes do not have hollow fangs to deliver a venomous bite or glands that produce venom. They are predators, however, and have many sharp, small teeth and can deliver a painful bite if they feel threatened.