Reptiles of North Carolina
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NC Records

Thamnophis saurita - Eastern Ribbonsnake


Photo: Jim Petranka and Candice Little
Photo: L. Eckart
Taxonomy
Class: Reptilia Order: Serpentes Family: Colubridae Subfamily: Natricinae Other Common Name(s): Eastern Ribbon Snake
Taxonomic Comments: Thamnophis currently consists of 38 species of slender to medium-sized natricid snakes, ranging widely across most of North America, from Canada through the majority of the United States and Mexico, south to Costa Rica.
Species Comments: Thamnophis saurita, the Eastern Ribbonsnake, is one of two Thamnophis in North Carolina. They range throughout eastern North America, from Nova Scotia to southern Florida and west to Michigan and the Mississipi River. In North Carolina, records exist primarily from the Coastal Plain and parts of the Piedmont; records from the Mountains are few.

Some authors recognize four subspecies, with T. s. saurita (Common Ribbonsnake) the most widely distributed (and the only one found in North Carolina). However, a complete molecular phylogenetic investigation of the ribbonsnakes is needed to determine whether these subspecies represent valid discrete units, or simply geographic variation across a widely-distributed taxon.

The generic epithet Thamnophis is derived from the Greek thamnos ("bush") and ophio ("snake"). The specific epithet saurita is Latinized Greek from sauros, meaning "lizard" (not New Latin as stated by Rossman (1970)).

Many texts list the specific epithet of this species as "sauritus", a change made by Holbrook in 1842, rather than "saurita", as described by Linneaus in 1766. Per Kraus and Cameron (2016), the epithet "saurita" was correctly applied as a noun in apposition, and the emendation to "sauritus" by Holbrook was unjustified. Thus, "saurita" is the correct specific epithet.

Taxonomic References: Rossman (1970), Kraus and Cameron (2016), Hallas et al. (2022).
Identification
Description: Eastern Ribbonsnakes are very slender snakes of medium length with long tails and a relatively small, slender head compared to other members of the genus. Dorsal coloration is dark olive or brown, with a prominent yellow middorsal stripe and two lateral stripes involving scale rows 3 and 4. The venter is a plain yellow. The top of the head is continuous with the dorsum, with cream to yellow labials lacking any dark bars between them, and a noticeable white bar present in the posterior portion of the preocular scale.
Morphological Features: Eastern Ribbonsnakes typically have 19 keeled scale rows at midbody, reducing to 17 posteriorly. Ventral counts range from 143–177 (141-169 in NC specimens; Palmer and Braswell, 1995), with 94-136 subcaudals (106-132) and an undivided anal plate. Head scale counts are variable, but typically as follows: 7 supralabials, 10 infralabials, 1 loreal, 1 preocular, 3 postoculars, and 1+2+3 temporals. Palmer and Braswell (1995) noted some variation in scalation across multiple specimens in NC.

These are typically medium-szied snakes, with a maximum total length of 101.8 cm (39.9 inches). Palmer and Braswell (1995) reported a 89.8 cm female specimen from NC. Tails are long, ranging up to 38% of total length. Males typically have longer tails and more subcaudals than females.

Eastern Ribbonsnakes lack enlarged posterior teeth or any venom-producing capability. When captured they typically writhe about, releasing musk and feces, and may occasionally bite if threatened, though they pose no danger to humans or pets.
Technical Reference: Palmer and Braswell (1995); Ernst and Ernst (2003).
Field Guide Descriptions: Palmer and Braswell (1995); Ernst and Ernst (2003); Beane et al. (2010).
Online Photos:    Google   iNaturalist   GBIF
Observation Methods: Eastern Ribbonsnakes may be incidentally encountered under cover objects along or near shallow streams and rivers. They can also be found crossing roads.
Distribution in North Carolina
County Map: Clicking on a county returns the records for the species in that county.
Key Habitat Requirements
Habitat: Ribbonsnakes occur principally around the margins of ponds, marshes, bogs, streams, and other wetland habitats, especially shorelines that are well-vegetated with herbs and shrubs (Palmer and Braswell, 1995; Beane et. al., 2015; Gibbons, 2017).
Life History and Autecology
Breeding and Courtship: Ribbonsnakes reach sexual maturity at body lengths of approximately 60 cm (Ernst and Ernst, 2003). Mating likely occurs in the spring.
Reproductive Mode: Ribbonsnakes are viviparous; young are born July to September. Litters average 8–10 neonates.

Neonates average approximately 20 cm in total length.
Aquatic Life History: Ribbonsnakes are semiaquatic and almost always found near marshes, ponds, streams, and canals, along banks or the water’s edge.
Terrestrial Life History: Ribbonsnakes can be found active both during the day and at night, often crossing roads between habitats when encountered. Ernst and Ernst (2003) suggest the species estivates during hot and dry summers. In the winter, these snakes will hibernate in ant mounds, crayfish burrows, mammal burrows and other holes near the water’s edge. Ribbonsnakes have been recorded in every month except January and December in North Carolina, with most activity in May–August.

Home range estimates are not known from North Carolina, but elsewhere are reported to be very small and always near a waterway. A study in Nova Scotia reported these snakes were always within 5 m of water, and almost always within a 50 m2 home range (Bell et al., 2007).
General Ecology
Adverse Environmental Impacts
Status in North Carolina
NHP State Rank: S4
Global Rank: G5
Status Comments: We suspect that oddly disjunct nature of the distribution of this species may be the result of the near elimination of beavers from North America close to the beginning of the 20th Century. Some recovery could then be expected following restoration efforts and the resulting current expansion of beaver populations over much of their former range.

Photo Gallery for Thamnophis saurita - Eastern Ribbonsnake

26 photos are shown.

Recorded by: Mary Stevens, Paul Hart
Harnett Co.
Comment: 		Recorded by: Robert Russo
Beaufort Co.
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Recorded by: Robert Russo
Beaufort Co.
Comment: 		Recorded by: Robert Russo
Beaufort Co.
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Recorded by: Robert Russo
Beaufort Co.
Comment: 		Recorded by: Robert Russo
Beaufort Co.
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Recorded by: L. Eckart
Carteret Co.
Comment: 		Recorded by: Paul Hart
Harnett Co.
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Recorded by: C. Teague
Beaufort Co.
Comment: 		Recorded by: Harry LeGrand
Alleghany Co.
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Recorded by: Travis McLain
Anson Co.
Comment: 		Recorded by: Travis McLain
Anson Co.
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Recorded by: Travis McLain
Anson Co.
Comment: 		Recorded by: L. Purvis
Guilford Co.
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Recorded by: Travis McLain
Cabarrus Co.
Comment: 		Recorded by: Travis McLain
Cabarrus Co.
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Recorded by: B. Bockhahn
Durham Co.
Comment: 		Recorded by: B. Bockhahn
Durham Co.
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Recorded by: Robert Russo
Beaufort Co.
Comment: 		Recorded by: Erich Hofmann and Kayla Weinfurther
Craven Co.
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Recorded by: Erich Hofmann and Kayla Weinfurther
Craven Co.
Comment: 		Recorded by: Mark Shields
Watauga Co.
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Recorded by: Mark Shields
Dare Co.
Comment: 		Recorded by: Erich Hofmann
Craven Co.
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Recorded by: Erich Hofmann
Pamlico Co.
Comment: 		Recorded by: Jim Petranka and Candice Little
Haywood Co.
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