Eastern ribbon snake (Thamnophis sauritus)

Also known as: blue-striped ribbon snake, Northern ribbon snake, Peninsula ribbon snake
GenusThamnophis (1)
SizeLength: 45 - 101 cm (2)

The eastern ribbon snake is classified as Least Concern (LC) on the IUCN Red List (1).

A shy, non-venomous reptile, the eastern ribbon snake (Thamnophis sauritus) is characterised by three bright, well-defined stripes which run down the centre of its back and along the sides of its body (2). The bold, distinctive stripes are usually yellow, contrasting with the dark body, and there is often a brownish or darkish band between the side stripes and the belly. The underside of the eastern ribbon snake is usually yellowish or greenish, without any distinct markings (3) (4).

The eastern ribbon snake has a slender body, and the scales of this species are strongly keeled. The tail is long, making up one-third of the total body length (2) (3) (4). The female eastern ribbon snake is usually longer and slightly thicker than the male, although they are otherwise very similar in appearance (2) (5). The juvenile eastern ribbon snake closely resembles the adult (2). 

There are four recognised subspecies of eastern ribbon snake: the nominate subspecies, the eastern ribbon snake (Thamnophis sauritus sauritus), has a reddish-brown back, yellow side stripes and a yellow or green-tinged stripe running along the centre of the back. The blue-striped ribbon snake (Thamnophis sauritus nitae) is usually velvety-black or dark brown on the back, with pale blue side stripes. The Peninsula ribbon snake (Thamnophis sauritus sackenii) has a tan or brown back, with light, narrow side stripes and a tan-coloured stripe on the back. The northern ribbon snake (Thamnophis sauritus septentrionalis) is dark brown-black on the back, and has yellow stripes along the sides and a yellow stripe on the back, which is often masked by brown pigment (2).

The eastern ribbon snake occurs in southeast Canada and in the eastern United States, where it ranges from Wisconsin to Maine, south to Louisiana, the Gulf Coast and Florida (1). It has also been reported to occur in the Bahamas, although whether or not this species has established there is currently uncertain (1) (6).

The four subspecies of the eastern ribbon snake have slightly different distributions. The eastern ribbon snake (T. s. sauritus) occurs from southern Indiana to Pennsylvania, New York and New Hampshire, south to Louisiana, the Florida Panhandle and South Carolina. The blue-striped ribbon snake (T. s. nitae) occurs on the Gulf Coast of Florida, while the Peninsula ribbon snake (T. s. sackenii) occurs in South Carolina and Georgia, and on the Florida Peninsula. The northern ribbon snake (T. s. septentrionalis) occurs from southern Ontario to Michigan, Maine, New Hampshire, Pennsylvania and Indiana (2).

The eastern ribbon snake is primarily associated with wet habitats, such as wet meadows, marshes, bogs, ponds, lake shorelines and streams (1) (2) (3) (4). It may also occur in seasonally flooded prairies, as well as wet or moist forest (1).

The eastern ribbon snake is usually found in sunny sites close to vegetation, such as shrubs or clumps of sedge or grass (1).

A semi-aquatic species, the eastern ribbon snake is almost always found in close proximity to water, typically basking in bushes or on logs and mounds along the water’s edge. An adept swimmer, this species will glide swiftly across the surface of water (2) (7), while on land it also moves quickly, with its head elevated (8). 

The eastern ribbon snake obtains most of its food from the water, feeding mainly on small fish, salamanders and frogs (2) (3) (4) (9). It also consumes a variety of invertebrates, such as leeches, harvester ants, worms, spiders and caterpillars (5) (9). The eastern ribbon snake has occasionally been observed to feed on carrion (5).

This species shelters in thick vegetation or in burrows dug by other animals. During the winter, the eastern ribbon snake hibernates underground, in burrows, ant mounds, or rocky areas on high ground (1) (5). The eastern ribbon snake is one of the more cold-tolerant snake species in North America, being one of the last to withdraw to its hibernation sites in the autumn and one of the earliest to emerge in the spring (8). The male eastern ribbon snake usually emerges from hibernation before the female (5).

The eastern ribbon snake breeds in the spring, usually around May (5) (7). It is viviparous, giving birth to between 3 and 26 live young in July or August (3) (5) (8). The young snakes usually reach maturity at about 2 years old, at a length of around 75 centimetres (8). 

Predators of the eastern ribbon snake include small mammals, such as otters, raccoons and minks, as well as a variety of other animals, including herons, and even other snakes, snapping turtles, bullfrogs and large fish (5) (9). The eastern ribbon snake defends itself against these predators primarily by concealment and camouflage, and will rapidly escape into dense vegetation or water when threatened (5). It sometimes gives a display which includes coiling the body and flattening the head when confronted by a predator (5). The eastern ribbon snake rarely bites, but will thrash about and release a foul-smelling musk from its anal glands when captured (3) (5) (7).

Although the eastern ribbon snake is not significantly threatened, local declines in this species have been observed throughout its range (1).

Habitat loss, specifically the degradation of riparian vegetation, is considered to be the primary threat to the eastern ribbon snake (1). Development around wetlands, lakes and streams has also had a significant impact on this species’ population (5).

Large numbers of eastern ribbon snakes are also killed after being struck by cars (1) (5).

Due to its large geographic range and its relatively large, stable population, the eastern ribbon snake is not currently the target of any specific conservation measures. The eastern ribbon snake is known to occur in a number of protected areas, which may afford it some level of protection (1). 

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  1. IUCN Red List (September, 2011)
  2. eNature Field Guide - Eastern ribbon snake (September, 2011)
  3. University of Georgia: Savannah River Ecology Lab Herpetology Program - Eastern ribbon snake (September, 2011)
  4. University of Massachusetts Ameherst: Natural Resources and Environmental Conservation - Eastern ribbon snake (September, 2011)
  5. Penn State University: Virtual Nature Trail at Penn State New Kensington - Eastern ribbon snake (September, 2011)
  6. Lee, D.S. (2005) Reptiles and amphibians introduced to the Bahamas: a potential conservation crisis. Bahamas Journal of Science, 12(2): 2-6.
  7. Beane, J.C., Braswell, A.L., Mitchell, J.C., Palmer, W.M. and Harrison, J.R. (2010) Amphibians and Reptiles of the Carolinas and Virginia, Second Edition. University of North Carolina Press, Chapel Hill, North Carolina.
  8. Bartlett, R.D. and Bartlett, P.P. (2005) Guide and Reference to the Snakes of Eastern and Central North America (North of Mexico). University Press of Florida, Gainesville, Florida.
  9. Linzey, D.W. and Clifford, M.J. (1981) Snakes of Virginia. University Press of Virginia, Charlottesville, Virginia.