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The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.




Nerodia taxispilota
Nerodia taxispilota
(Brown Watersnake)
Reptiles-Snakes
Native Transplant
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Nerodia taxispilota (Holbrook, 1838)

Common name: Brown Watersnake

Taxonomy: available through www.itis.govITIS logo

Identification: Nerodia taxispilota is a brown snake of varying hues with a row of darker brown, distinct, large, squared blotches middorsally, alternating with squared blotches in lateral rows that do not or rarely interconnect with the middorsal row (Wright and Wright, 1957; Behler and King, 1979; Ashton and Ashton, 1981; Ernst and Barbour, 1989; Conant and Collins, 1998; Tennant and Bartlett, 2000).  This dorsal pattern is unique and not exhibited in any other U.S. species of Nerodia.  The dorsal scales are keeled (Behler and King, 1979; Conant and Collins, 1998).  On the head there are no subocular scales, 2-4 anterior temporal scales, and 11-13 lower labial scales (Powell et al., 1998).  Brown Watersnakes vary in total length from 76-182 cm (30-74 in) (Ernst and Barbour, 1989; Conant and Collins, 1998).  Numerous illustrations of N. taxispilota have been published (Wright and Wright, 1957; Mount, 1975; Behler and King, 1979; Martof et al., 1980; Ashton and Ashton, 1981; Linzey and Clifford, 1981; Smith and Brodie, 1982; Jackson, 1983; Ernst and Barbour, 1989; Carmichael and Williams, 1991; Palmer and Braswell, 1995; Tennant, 1997; Conant and Collins, 1998; Behler, 1999; Tennant and Bartlett, 2000).

Size: 76-182 cm total length

Native Range: Brown Watersnakes are primarily indigenous to the Coastal Plain of the eastern United States, ascending streams into the Piedmont; this includes Alabama, Florida, Georgia, North Carolina, South Carolina, and extreme southeastern Virginia (Martof, 1956; Wright and Wright, 1957; Mount, 1975; Stevenson, 1976; Behler and King, 1979; Linzey, 1979; Martof et al., 1980; Ashton and Ashton, 1981; Linzey and Clifford, 1981; Jackson, 1983; McCranie, 1983; Tobey, 1985; Moler, 1988; Ernst and Barbour, 1989; Carmichael and Williams, 1991; Mitchell, 1994; Palmer and Braswell, 1995; Tennant, 1997; Conant and Collins, 1998; King, 2000; Tennant and Bartlett, 2000).
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Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Nonindigenous Occurrences:

Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Nerodia taxispilota are found here.

StateYear of earliest observationYear of last observationTotal HUCs with observations†HUCs with observations†
Colorado198519851Upper South Platte

Table last updated 5/25/2018

† Populations may not be currently present.


Means of Introduction: Unknown.

Status: Not established.

Impact of Introduction: If a population of N. taxispilota became established, there is potential for this species to compete with indigenous western species of Nerodia and Thamnophis (garter snakes), and negatively impact any indigenous species of fish upon which it can feed.

Remarks: The taxonomy of N. taxispilota has been reviewed by McCranie (1983) and Boundy et al. (2000).  Literature and natural history reviews of N. taxispilota have been compiled by Wright and Wright (1957, 1962), McCranie (1983), Ernst and Barbour (1989), and Gibbons and Semlitsch (1991).  Scientific and standard English names follow Crother (2008).

These large aquatic snakes are primarily diurnal but a few individuals may become somewhat nocturnal during hot summer months (Ernst and Barbour, 1989; Blem and Blem, 1990; Gibbons and Semlitsch, 1991; Conant and Collins, 1998).  The diet of N. taxispilota primarily seems to be live fish (Ernst and Barbour, 1989; Gibbons and Semlitsch, 1991; Palmer and Braswell, 1995; Conant and Collins, 1998), although dead fish may be scavenged (Blem and Blem, 1990; Tennant, 1997; Tennant and Bartlett, 2000).  Brown watersnakes may inhabit any body of water but prefer larger waters and their main tributaries (Ernst and Barbour, 1989; Gibbons and Semlitsch, 1991; Mills et al., 1995; Palmer and Braswell, 1995).  Nerodia taxispilota prefers elevated perches for basking near or above water such as trees, vines, and logs (Gibbons and Semlitsch, 1991; Mitchell, 1994; Mills et al., 1995; Palmer and Braswell, 1995; Conant and Collins, 1998).  In rivers, N. taxispilota prefer backwater areas and the outer bends of rivers with steep banks characterized by plenty of potential perch sites (Mills et al., 1995; Zug et al., 2001).  Smaller individuals bask in smaller branches and vines, while larger snakes prefer banks, logs, and roots (Mills et al., 1995).  Some individuals may climb trees to a height of more than 6 m (20 ft) (Conant and Collins, 1998).  When handled, these nonvenomous watersnakes bite viciously and release large quantities of feces in addition to a malodorous musk from their anal glands (Wright and Bishop, 1915; Ernst and Barbour, 1989; Mitchell, 1994; Palmer and Braswell, 1995).

Nerodia taxispilota is viviparous; females give live birth to 9-61 young on land in summer or fall (Ernst and Barbour, 1989; Blem and Blem, 1990; Palmer and Braswell, 1995).

References: (click for full references)

Ashton, R. E., Jr., and P. S. Ashton. 1981. Handbook of Reptiles and Amphibians of Florida. Part One. The Snakes. Windward Publishing, Inc., Miami. 176 pp.

Behler, J. L. 1999. National Audubon Society First Field Guide. Reptiles. Scholastic, Inc., New York. 160 pp.

Behler, J. L., and F. W. King. 1979. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, Inc., New York. 743 pp.

Blem, C. R., and L. B. Blem. 1990. Lipid reserves of the brown water snake Nerodia taxispilota. Comparative Biochemistry and Physiology 97A(3):367-372.

Boundy, J., J. [A.] Campbell, B. [I.] Crother, and T. Taggart. 2000. Squamata—snakes. Pp. 56-74. In: B. I. Crother (chair), and Committee on Standard English and Scientific Names (editors). Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. Society for the Study of Amphibians and Reptiles Herpetological Circular (29):i-iii, 1-82.

Carmichael, P., and W. Williams. 1991. Florida's Fabulous Reptiles and Amphibians. World Publications, Tampa. 120 pp.

Conant, R., and J. T. Collins. 1998. A Field Guide to Reptiles & Amphibians. Eastern and Central North America. Third Edition, Expanded. Houghton Mifflin Company, Boston. 616 pp.

Crother, B.I. (chair). Committee on Standard and English and Scientific Names. 2008. Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. Society for the Study of Amphibians and  Reptiles Herpetological Circular. No. 37. iii + 86p.

Ernst, C. H., and R. W. Barbour. 1989. Snakes of Eastern North America. George Mason University Press, Fairfax, Virginia. 282 pp.

Gibbons, J. W., and R. D. Semlitsch. 1991. Guide to the Reptiles and Amphibians of the Savannah River Site. The University of Georgia Press, Athens, Georgia, and London. 131 pp.

Jackson, J. J. 1983. Snakes of the Southeastern United States. Publications Section, Georgia Extension Service, [Athens, Georgia]. 112 pp.

King, F. W. 2000. Florida Museum of Natural History's Checklist of Florida Amphibians and Reptiles [online]. Florida Museum of Natural History, University of Florida, Gainesville. Available on URL: http://www.flmnh.ufl.edu/herps/FL-GUIDE/Flaherps.htm.

Linzey, D. W. 1979. Snakes of Alabama. The Strode Publishers, Inc., Huntsville, Alabama. 136 pp.

Linzey, D. W., and M. J. Clifford. 1981. Snakes of Virginia. University Press of Virginia, Charlottesville. 159 pp.

Livo, L. J., G. A. Hammerson, and H. M. Smith. 1998. Summary of amphibians and reptiles introduced into Colorado. Northwestern Naturalist 79(1):1-11.

Martof, B. S. 1956. Amphibians and Reptiles of Georgia. University of Georgia Press, Athens, Georgia. 94 pp.

Martof, B. S., W. M. Palmer, J. R. Bailey, and J. R. Harrison III. 1980. Amphibians and Reptiles of the Carolinas and Virginia. The University of North Carolina Press, Chapel Hill. 264 pp.

McCranie, J. R. 1983. Nerodia taxispilota. Catalogue of American Amphibians and Reptiles (331):1-2.

Mills, M. S., C. J. Hudson, and H. J. Berna. 1995. Spatial ecology and movements of the brown water snake (Nerodia taxispilota). Herpetologica 51(4):412-423.

Mitchell, J. C. 1994. The Reptiles of Virginia. Smithsonian Institution Press, Washington and London. 352 pp.

Moler, P. 1988. A Checklist of Florida's Amphibians and Reptiles. Nongame Wildlife Program, Florida Game and Fresh Water Fish Commission, Tallahassee. 18 pp.

Mount, R. H. 1975. The Reptiles and Amphibians of Alabama. Auburn University Agricultural Experiment Station, Auburn. 347 pp.

Palmer, W. M., and A. L. Braswell.1995. Reptiles of North Carolina. The University of North Carolina Press for North Carolina State Museum of Natural Sciences, Chapel Hill and London. 412 pp.

Powell, R., J. T. Collins, and E. D. Hooper, Jr. 1998. A Key to Amphibians & Reptiles of the Continental United States and Canada. University Press of Kansas, Lawrence. 131 pp.

Smith, H. M., and E. D. Brodie, Jr. 1982. A Guide to Field Identification. Reptiles of North America. Golden Press, New York. 240 pp.

Stevenson, H. S. 1976. Vertebrates of Florida. Identification and Distribution. University Presses of Florida, Gainesville. 607 pp.

Tennant, A. 1997. A Field Guide to Snakes of Florida. Gulf Publishing Company, Houston. 257 pp.

Tennant, A., and R. D. Bartlett. 2000. Snakes of North America. Eastern and Central Regions. Gulf Publishing Company, Houston. 588 pp.

Toby, F. J. 1985. Virginia's Amphibians and Reptiles: A Distributional Survey. Virginia Herpetological Society, [Richmond]. 114 pp.

Wright, A. H., and S. C. Bishop. 1915. A biological reconnaissance of the Okefenokee Swamp in Georgia. The Reptiles. II. Snakes. Proceedings of the Academy of Natural Sciences of Philadelphia 67:139-192, plate III.

Wright, A. H., and A. A. Wright. 1957. Handbook of Snakes of The United States and Canada. Volumes I-II. Comstock Publishing Associates, Ithaca and London. 1105 pp.

Wright, A. H., and A. A. Wright. 1962. Handbook of Snakes of the United States and Canada. Volume III. Bibliography. A. H. and A. A. Wright, Ithaca. 179 pp. [Reprinted 1979 by Society for the Study of Amphibians and Reptiles, Oxford, Ohio.]

Zug, G. R., L. J. Vitt, and J. P. Caldwell. 2001. Herpetology. An Introductory Biology of Amphibians and Reptiles. Second Edition. Academic Press, San Diego. 630 pp.

Author: Somma, L.A.

Revision Date: 10/27/2009

Citation Information:
Somma, L.A., 2019, Nerodia taxispilota (Holbrook, 1838): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=1196, Revision Date: 10/27/2009, Access Date: 9/20/2019

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.

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The data represented on this site vary in accuracy, scale, completeness, extent of coverage and origin. It is the user's responsibility to use these data consistent with their intended purpose and within stated limitations. We highly recommend reviewing metadata files prior to interpreting these data.

Citation information: U.S. Geological Survey. [2019]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [9/20/2019].

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