A Guide to the Amphibians
and Reptiles of California

Nerodia fasciata - Southern Watersnake

Click on a picture for a larger view

Range Introduction in California: Red

iPhone App
Electronic Field Guide to the
Reptiles and Amphibians of
Southern California
Available Now at the
iTunes App Store.

Introduced: not native to California

It is against the law to capture, move, possess, collect, or distribute this invasive species in California.

If you find an aquatic snake in California that you think is a Watersnake (Nerodia), please send pictures
of it to the California Nerodia Site, which is tracking the distribution of this potential threat to native fish and wildlife.

Adult, Sacramento County. © Gary Nafis. Specimen courtesy of Eric Stitt

Adult, Sacramento County

Two adults breeding on top of
a log in a pond in Sacramento County

Adult, Los Angeles County © Jonathan Hakim

Adult, Los Angeles County

Adult, Sacramento County,
© Eric Stitt

Adult, San Joaquin County. © Edgar Ortega

The species of this Nerodia is unclear. It is included here until I find out exactly what it is.
Environmentalists fear that the Nerodia introduced into Folsom and Roseville may eventually find their way into the Central Valley where they could out-compete the already endangered Giant Gartersakes. This one was found in an irrigation canal near Manteca in May, 2011. It could indicate that these snakes have already spread into Valley waters, or it could be a single snake released in that area or even a new population of alien Nerodia.

Habitat

Habitat, Los Angeles County
© Jonathan Hakim

Habitat, Los Angeles County

Habitat, Sacramento County

More pictures of the Florida Watersnake Subspecies - N. f. pictiventris, in Florida

Description

Nonvenomous

Considered harmless to humans, but the snake's saliva may produce inflammatory reactions around the site of a bite.

Size

Adults are generally 22 - 40 inches long (56 - 101 cm) and up to 60 inches (152 cm.)

Appearance

A dark, heavy-bodied snake with heavily-keeled scales. Color is yellowish to reddish-gray with 40 or more dark crossbands on the entire length of the body. Old snakes may be almost entirely solid dark brown. There is a dark stripe extending from the eye to the corner of the mouth. The head has a more acute downward angle than Nerodia sipedon.

Dark spots mark the venter, typically dark square or triangular spots sometimes with wavy cross lines.

Juveniles are paler with a stronger pattern than adults.

Behavior

Active during the day, and also at night. If threatened, may emit a strong-smelling musk and feces from its cloaca, flatten its body and strike repeatedly. Basks in the sun at water's edge on logs or overhanging limbs, moving into dens along banks in cold weather. Will leave the water and travel overland a mile or more in search of food.

Diet

Eats fish, frogs, salamanders, crayfish.

Reproduction

Live-bearing.

Range

Introduced in and around Lake Natoma in the city of Folsom, Sacramento County (Balfour et al. 2007. Herpetol. Rev. 38:489), and in Harbor City, Los Angeles County (Balfour and Stitt 2002. Herpetol. Rev. 33:150).

According to Michael Fuller of the Nerodia Working Group, a reproducing population of N. fasciata has existed in Harbor City for several years. While the snakes key out to N. f. pictiventris morphologially, preliminary mDNA results (as of 9/08) suggest that they are Nerodia clarkii, or possibly hybrids of N. clarkii and N. f. pictiventris. The habitat is a freshwater lake, typical of that used by N. fasciata, while N. clarkii typically inhabit brackish waters.

Habitat

Occurs in and around permanent bodies of water, especially those bordered by woods.

Conservation Issues (Conservation Status)

Spread of this snake downstream into the Sacramento Valley could possibly threaten populations of the already endangered Giant Gartersnake, Thamnophis gigas. It could also pose a threat to other native fish and wildlife.

As of Janurary 2008 it is against the law to capture, move, possess, collect, import, or distribute this invasive species and all non-native water snakes of the genus Nerodia in California without a permit: California Department of Fish and Game (Sec. 671, Title 14, Calif. Code of Regulations).
See: California Department of Fish and Game Restricted Species Regulations

Taxonomy
Family	Colubridae	Colubrids
Genus	Nerodia	American Watersnakes
Species	fasciata	Southern Watersnake
Original Description
Nerodia fasciata - (Linnaeus, 1766) - Syst. Nat., 12th ed., Vol. 1, p. 378 from Original Description Citations for the Reptiles and Amphibians of North America © Ellin Beltz
Meaning of the Scientific Name
Nerodia - Greek - nereis - name of sea nymph fasciata - Latin - banded - refers to the banded pattern on dorsum from Scientific and Common Names of the Reptiles and Amphibians of North America - Explained © Ellin Beltz
Alternate Names
Southern Water Snake
Related or Similar California Snakes
Thamnophis sirtalis fitchi - Valley Gartersnake Thamnophis gigas - Giant Gartersnake Nerodia sipedon - Northern Watersnake
More Information and References
California Nerodia - a website about introduced populations of Nerodia found in California. Natureserve Explorer California Dept. of Fish and Game The Southern Watersnake (Nerodia fasciata) in Folsolm California (PDF) Gibbons, J. Whitfield, Michael E. Dorcas. North American Watersnakes - A Natural History. University of Oklahoma Press. 2004. Balfour, P. S., and E. W. Stitt. 2002. Geographic distribution: Nerodia fasciata fasciata. Herpetological Review 33:150. Conant, Roger, & Collins, Joseph T. A Field Guide to Reptiles and Amphibians Eastern and Central North America Third Edition. Houghton Mifflin Company, 1998. Bartlett, R.D., & Alan Tennant. Snakes of North America - Eastern and Central Regions. Gulf Publishing Co., 2000.

Conservation Status
The following status listings come from the Special Animals List which is published by the California Department of Fish and Wildlife. It is against the law to capture, move, possess, collect, or distribute this invasive species in California. See: California Department of Fish and Game Restricted Species Regulations
Organization	Status Listing
U.S. Endangered Species Act (ESA)	None
California Endangered Species Act (CESA)	None
California Department of Fish and Wildlife	None
Bureau of Land Management	None
USDA Forest Service	None
Natureserve Global Conservation Status Ranks
World Conservation Union - IUCN Red List

Return to the Top