Thamnophis sauritus - (Linnaeus, 1766)
Eastern Ribbonsnake
Other English Common Names: Eastern Ribbon Snake, eastern ribbonsnake
Taxonomic Status: Accepted
Related ITIS Name(s): Thamnophis sauritus (Linnaeus, 1766) (TSN 174134)
French Common Names: couleuvre mince
Unique Identifier: ELEMENT_GLOBAL.2.103516
Element Code: ARADB36120
Informal Taxonomy: Animals, Vertebrates - Reptiles - Snakes
Kingdom Phylum Class Order Family Genus
Animalia Craniata Reptilia Squamata Colubridae Thamnophis
Genus Size: D - Medium to large genus (21+ species)
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Concept Reference
Concept Reference: Collins, J. T. 1990. Standard common and current scientific names for North American amphibians and reptiles. 3rd ed. Society for the Study of Amphibians and Reptiles. Herpetological Circular No. 19. 41 pp.
Concept Reference Code: B90COL01NAUS
Name Used in Concept Reference: Thamnophis sauritus
Taxonomic Comments: Referred to as T. sirtalis by some authors in late 1940s and early 1950s.
Conservation Status

NatureServe Status

Global Status: G5
Global Status Last Reviewed: 07Sep2006
Global Status Last Changed: 26Feb1997
Rounded Global Status: G5 - Secure
Nation: United States
National Status: N5 (05Oct1996)
Nation: Canada
National Status: N3 (15Dec2012)

U.S. & Canada State/Province Status
United States Alabama (S5), Connecticut (S3S4), Delaware (S2), District of Columbia (S4), Florida (S5), Georgia (S5), Illinois (S1), Indiana (SNR), Kentucky (S3), Louisiana (S4), Maine (S3), Maryland (S5), Massachusetts (S4S5), Michigan (S5), Mississippi (S5), New Hampshire (S5), New Jersey (S5), New York (S4), North Carolina (S4), Ohio (SNR), Pennsylvania (S3), Rhode Island (S3), South Carolina (SNR), Tennessee (S4S5), Vermont (S2), Virginia (S5), West Virginia (S2), Wisconsin (S1)
Canada Nova Scotia (S2S3), Ontario (S3), Quebec (S1)

Other Statuses

Implied Status under the Committee on the Status of Endangered Wildlife in Canada (COSEWIC):PS: T,SC
Comments on COSEWIC: In November 2012, COSEWIC designated the Great Lakes population as Special Concern and the Atlantic population as Threatened.
IUCN Red List Category: LC - Least concern

NatureServe Global Conservation Status Factors

Range Extent: 200,000-2,500,000 square km (about 80,000-1,000,000 square miles)
Range Extent Comments: The range extends from Wisconsin to southern Maine and Nova Scotia, and south discontinuously to southeastern Louisiana, the Gulf Coast, and southern Florida (Conant and Collins 1991, Rossman et al. 1996, Ernst and Ernst 2003). This species has been reported from the Bahamas but may not be established there (see Powell and Henderson 1999).

Number of Occurrences: 81 to >300
Number of Occurrences Comments: This species is represented by a large number of occurrences (subpopulations).

Population Size: 100,000 to >1,000,000 individuals
Population Size Comments: Adult population size is unknown but presumably exceeds 100,000. This snake is locally common in many parts of its large range.

Number of Occurrences with Good Viability/Integrity: Many to very many (41 to >125)

Overall Threat Impact: Medium
Overall Threat Impact Comments: In most areas, this snake is not significantly threatened. Ernst and Ernst (2003) stated that populations are declining over much of the range because of habitat destruction, but this likely pertains primarily to peripheral populations or areas where the species is naturally rare. Degradation of shoreline vegetation is believed to result in population declines (Harding 1997). Locally, large numbers are killed on roads (Rossman et al. 1996), but this may be more a reflection of local abundance than a significant threat.

Short-term Trend: Relatively Stable (<=10% change)
Short-term Trend Comments: Populations may be declining in some areas (Ernst and Ernst 2003), but overall the extent of occurrence, area of occupancy, number of subpopulations, and population size probably are relatively stable or declining at a rate of less than 10 percent over 10 years or three generations.

Long-term Trend: Decline of <30% to increase of 25%

Other NatureServe Conservation Status Information

Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) The range extends from Wisconsin to southern Maine and Nova Scotia, and south discontinuously to southeastern Louisiana, the Gulf Coast, and southern Florida (Conant and Collins 1991, Rossman et al. 1996, Ernst and Ernst 2003). This species has been reported from the Bahamas but may not be established there (see Powell and Henderson 1999).

U.S. States and Canadian Provinces
Color legend for Distribution Map
Endemism: occurs (regularly, as a native taxon) in multiple nations

U.S. & Canada State/Province Distribution
United States AL, CT, DC, DE, FL, GA, IL, IN, KY, LA, MA, MD, ME, MI, MS, NC, NH, NJ, NY, OH, PA, RI, SC, TN, VA, VT, WI, WV
Canada NS, ON, QC

Range Map
Note: Range depicted for New World only. The scale of the maps may cause narrow coastal ranges or ranges on small islands not to appear. Not all vagrant or small disjunct occurrences are depicted. For migratory birds, some individuals occur outside of the passage migrant range depicted.

Range Map Compilers: NatureServe, 2005

U.S. Distribution by County Help
State County Name (FIPS Code)
CT Fairfield (09001), Hartford (09003), Litchfield (09005), Middlesex (09007), New Haven (09009), New London (09011), Tolland (09013), Windham (09015)
DE Kent (10001), New Castle (10003), Sussex (10005)
FL Monroe (12087)
IL Crawford (17033), Edwards (17047), Johnson (17087), Lawrence (17101), Massac (17127), Pope (17151)*, Pulaski (17153), Wayne (17191)
KY Butler (21031), Caldwell (21033), Calloway (21035), Carlisle (21039), Daviess (21059), Fulton (21075)*, Graves (21083), Hancock (21091), Hardin (21093)*, Henderson (21101), Hickman (21105), Hopkins (21107), Larue (21123), Logan (21141), Lyon (21143)*, Marshall (21157), McCracken (21145), McLean (21149), Muhlenberg (21177), Ohio (21183), Trigg (21221)
ME Cumberland (23005), Hancock (23009), Kennebec (23011), Oxford (23017), Sagadahoc (23023), Waldo (23027)*, York (23031)
PA Butler (42019), Centre (42027), Chester (42029), Crawford (42039), Luzerne (42079), Lycoming (42081), Mercer (42085), Monroe (42089), Northampton (42095), Pike (42103), Schuylkill (42107), Snyder (42109), Susquehanna (42115), Venango (42121), York (42133)
RI Kent (44003), Newport (44005), Providence (44007), Washington (44009)
VT Addison (50001), Chittenden (50007)*, Rutland (50021), Windham (50025)
WI Adams (55001)*, Columbia (55021)*, Door (55029), Marinette (55075)*, Sauk (55111)*, Sheboygan (55117)
WV Barbour (54001)*, Greenbrier (54025)*, Hardy (54031)*, Mason (54053)*, Monroe (54063)*, Preston (54077)*, Randolph (54083)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
01 Lower Kennebec (01030003)+, Maine Coastal (01050002)+, Presumpscot (01060001)+, Saco (01060002)+, Piscataqua-Salmon Falls (01060003)+, West (01080107)+, Lower Connecticut (01080205)+, Farmington (01080207)+, Blackstone (01090003)+*, Narragansett (01090004)+, Pawcatuck-Wood (01090005)+, Quinebaug (01100001)+, Shetucket (01100002)+, Thames (01100003)+, Quinnipiac (01100004)+, Housatonic (01100005)+, Saugatuck (01100006)+
02 Middle Delaware-Mongaup-Brodhead (02040104)+, Middle Delaware-Musconetcong (02040105)+, Brandywine-Christina (02040205)+, Broadkill-Smyrna (02040207)+, Chincoteague (02040303)+, Upper Susquehanna (02050101)+, Upper Susquehanna-Lackawanna (02050107)+, Lower West Branch Susquehanna (02050206)+, Lower Susquehanna-Penns (02050301)+, Upper Juniata (02050302)+, Lower Susquehanna-Swatara (02050305)+, Lower Susquehanna (02050306)+, Chester-Sassafras (02060002)+, Cacapon-Town (02070003)+*, Pokomoke-Western Lower Delmarva (02080111)+
03 Florida Bay-Florida Keys (03090203)+
04 Manitowoc-Sheboygan (04030101)+, Door-Kewaunee (04030102)+, Peshtigo (04030105)+*, Upper Fox (04030201)+*, Milwaukee (04040003)+, Mettawee River (04150401)+, Winooski River (04150403)+*, Lake Champlain (04150408)+
05 French (05010004)+, Tygart Valley (05020001)+, Cheat (05020004)+*, Youghiogheny (05020006)+*, Shenango (05030102)+, Connoquenessing (05030105)+, Middle New (05050002)+*, Greenbrier (05050003)+*, Raccoon-Symmes (05090101)+*, Upper Green (05110001)+, Middle Green (05110003)+, Rough (05110004)+, Lower Green (05110005)+, Pond (05110006)+, Embarras (05120112)+, Lower Wabash (05120113)+, Little Wabash (05120114)+, Lower Cumberland (05130205)+, Red (05130206)+*, Lower Ohio-Little Pigeon (05140201)+, Highland-Pigeon (05140202)+, Lower Ohio-Bay (05140203)+*, Tradewater (05140205)+, Lower Ohio (05140206)+
06 Lower Tennessee (06040006)+
07 Castle Rock (07070003)+*, Cache (07140108)+
08 Bayou De Chien-Mayfield (08010201)+, Obion (08010202)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
Reproduction Comments: Gives birth to 3-26 (average about 9) young in July or August; captives have produced 2 litters in a season; sexually mature in 2-3 years in Michigan (Fitch 1970).
Ecology Comments: Home range averaged 0.8 ha in Michigan study (see DeGraaf and Rudis 1983).
Non-Migrant: N
Locally Migrant: Y
Long Distance Migrant: N
Mobility and Migration Comments: May migrate between aquatic edge habitat and hibernaculum on higher ground (Minton 1972).
Riverine Habitat(s): CREEK, Low gradient, Pool
Lacustrine Habitat(s): Shallow water
Terrestrial Habitat(s): Bare rock/talus/scree
Special Habitat Factors: Burrowing in or using soil, Fallen log/debris
Habitat Comments: Habitats include wet meadows, marshes, seasonally flooded prairies, bogs, ponds, lake shorelines, swamps, and shallow slow streams; also hardwood hammocks and other wet or moist forest in some areas; usually this snake is in or near vegetative cover (often shrubs or clumps of sedges or grasses) in sun-exposed sites along the edge of standing or flowing water; it climbs into low vegetation, rarely into tree canopy (Bishop and Farrell, 1994, Herpetol. Rev. 25:127; Rossman et al. 1996, Harding 1997, Ernst and Ernst 2003). Shelters include thick vegetation, muskrat lodges, or burrows. Hibernation sites are in burrows, ant mounds, underground on high ground (sometimes high on rocky slopes), or underwater.
Adult Food Habits: Carnivore, Piscivore
Immature Food Habits: Carnivore, Piscivore
Food Comments: Primary diet includes amphibians and fishes. Most prey is obtained in water or on the ground near water, sometimes in vegetation.
Adult Phenology: Circadian, Diurnal, Hibernates/aestivates
Immature Phenology: Circadian, Diurnal, Hibernates/aestivates
Phenology Comments: Active diurnally April-October in north; active season longer in south, where activity may occur day or night.
Length: 102 centimeters
Economic Attributes Not yet assessed
Management Summary Not yet assessed
Population/Occurrence Delineation
Group Name: Medium And Large Colubrid Snakes

Use Class: Not applicable
Minimum Criteria for an Occurrence: Occurrences are based on evidence of historical presence, or current and likely recurring presence, at a given location. Such evidence minimally includes collection or reliable observation and documentation of one or more individuals (including eggs) in or near appropriate habitat where the species is presumed to be established and breeding.
Separation Barriers: Busy highway or highway with obstructions such that snakes rarely if ever cross successfully; major river, lake, pond, or deep marsh (this barrier pertains only to upland species and does not apply to aquatic or wetland snakes); densely urbanized area dominated by buildings and pavement.
Separation Distance for Unsuitable Habitat: 1 km
Separation Distance for Suitable Habitat: 10 km
Separation Justification: Available information on movements of colubrid snakes is limited to a small minority of species. These data indicate that nearly all species have home ranges smaller or much smaller than 25 ha (e.g., less than 3 ha, Pituophis catenifer in California, Rodriguez-Robles 2003), with some up to about 75 ha (Heterodon platirhinos, average 50 ha, Plummer and Mills 2000), and the largest up to 225 ha in the biggest colubrids (Drymarchon, summer mean 50-100 ha, USFWS 1998).

Radiotelemetry data for Pantherophis indicate that residents of hibernacula that are 1-2 km apart (with suitable intervening habitat) probably interbreed (Prior et al. 1997, Blouin-Demers and Weatherhead 2002). However, "evidence of genetic structure even over short distances (e.g., 2-20 km) implies that gene flow among rat snake populations can be easily disrupted" (Prior et al. 1997). Loughheed et al. (1999) found evidence of substantial genetic exchange among local hibernacula (< 6 km apart), but gene flow over distances of 10s of km appears to be substantially less. Based on extensive radio-tracking data, Blouin-Demers and Weatherhead (2002) found that home range size of Pantherophis averaged 18.5 ha and ranged up to 93 ha; based on the most mobile individuals, Pantherophis from hibernacula up to 8 km apart can come together for mating. Pantherophis and probably other colubrids exhibit high fidelity to hibernacula and shift even to nearby sites only rarely (Prior et al. 2001).

Many of the several studies that report small home ranges for colubrids did not employ methods (e.g., radio telemetry) suitable for detecting full annual or multi-annual home range size, dispersal, or other long-distance movements, so these may have yielded underestimates of home ranges or activity areas.

At least some colubrids, including medium-sized species such as garter snakes, not uncommonly move between areas up to a few kilometers apart, and several species make extensive movements of up to several kilometers, so separation distances of 1-2 km for suitable habitat are too small for medium-sized and large colubrids.

A separation distance of 10 km for suitable habitat was selected as most appropriate for snakes assigned to this Specs Group because it seems generally unlikely that two locations separated by less than 10 km of suitable habitat would represent distinct occurrences.

For the purposes of these occurrence specifications, upland habitat is regarded as unsuitable habitat for aquatic and wetland snakes. For upland snakes, shallow or patchy wetlands are treated as unsuitable habitat whereas large deepwater habitats (subjective determination) are barriers.

Inferred Minimum Extent of Habitat Use (when actual extent is unknown): .5 km
Date: 12Feb2013
Author: Hammerson, G.
Notes: Separation distance for suitable habitat was changed from 5 km to 10 km based on comments from Dale Jackson (12 Feb 2013).
Population/Occurrence Viability
U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
NatureServe Conservation Status Factors Edition Date: 07Sep2006
NatureServe Conservation Status Factors Author: Hammerson, G.
Element Ecology & Life History Edition Date: 07Sep2006
Element Ecology & Life History Author(s): Hammerson, G.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

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