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Scientific name: Thamnophis sauritus
Common name: 
Ribbon Snake

(Information in this Species Page was compiled by Jennifer Sensor in Biology 220M, Spring 2005, at Penn State New Kensington)

The ribbon snake is a member of the garter snake group (the genus Thamnophis). Ribbon snakes can be distinguished from their close relatives the true garter snakes by their slender body shape, glossy scales, and relatively longer tails. Like the true garter snakes, ribbon snakes have prominent lateral body stripes and are shy, non-poisonous reptiles.

There are four sub-species of ribbon snake: the eastern ribbon snake (T. sauritus sauritus), the northern ribbon snake (T. sauritus septentrionalis), the blue striped ribbon snake (T. sauritus nitae), and the peninsula ribbon snake (T. sauritus sackenii). These snakes are all an overall reddish brown, tan, or black with three prominent stripes running the lengths of their bodies. These stripes may be yellow, green, brown, or even (in T.sauritus nitae) light blue. Their bellies are most often lighter in color (bright white, off-white, yellow, or green) but may also be dark brown or even black. As in many snake species, the variability of specific colorations is the rule rather than the exception. Specific habitat adaptations and intense selection (primarily through predator pressures) generates an extremely wide range of color patterns. The eastern ribbon snake is between 18 and 34 inches long while the northern ribbon snake is shorter (between 16 and 26 inches long). Females tend to be somewhat longer and also thicker than males. The tail of a ribbon snake is quite long (around 1/3 of the total length of the snake). This longer tail, as mentioned above, is an excellent way to distinguish ribbon snakes from the shorter tailed "true" garter snakes.

Ribbon snakes are widely distributed throughout the United States. The two sub-species expected to be found in Western Pennsylvania are the eastern and northern ribbon snakes. The eastern ribbon snake is found throughout the eastern United States from southern Maine (and Ontario, Canada) down to parts of Florida westward to the Mississippi River. The northern ribbon snake is found in northern New England across New York westward through Western Pennsylvania, Michigan, Illinois, and Wisconsin. Interestingly, an isolated population of northern ribbon snakes is located in Nova Scotia, Canada.

Ribbon snakes can be found in a great variety of specific habitats. The key factor for their presence is the proximity of a water source in which the snakes can swim and capture aquatic prey. Ribbon snakes are found in forests and rocky hillsides, and most frequently are seen climbing or resting in the dense vegetation around a bog, lake, marsh, pond, stream, river, or even seeping spring. Ribbon snakes may use a variety of animal burrows as shelters but seem to prefer to be out in the dense, but sunlit vegetation. They rely on their camouflaging colorations both for protection and for concealment from potential prey.

Prey and Predators
Ribbon snakes use both visual and olfactory sensory systems to detect prey. Like true garter snakes, they only eat "cold blooded" prey including fish, newts and salamanders, frogs (both adults and tadpoles), earthworms, spiders, caterpillars, and a great variety of other insects. Ribbon snakes have even been observed to eat carrion (including road-killed toads). Ribbon snakes are in turn eaten by a wide variety of predators including large fish, weasels and many other carnivorous mammals, wading birds, raptors, milk snakes, racers, eastern hognose snakes, cottonmouth snakes, and rattlesnakes. Young ribbon snakes may also be eaten by turtles, smaller fish, and even crayfish. Defenses against predation include first and foremost concealment and camouflage, but also may involve displays (coiling and head flattening), and very rapid retreats both through dense vegetation (a path highly favored by their very thin body shapes) and through water (they are very rapid swimmers). The lateral stripes on these snakes are thought to be very effective in confusing predators as to the speed and direction of the moving snake. Actual striking and biting at a source of disturbance or danger is very seldom observed in ribbon snakes.

Protective Behaviors
If a ribbon snake is captured, excessively disturbed, or handled roughly it will squirm about wildly and spray its tormentor with foul smelling anal gland musk and expelled feces. It is also capable of shedding its tail which will then continue to thrash about ideally confusing the predator so that the snake may make a quick escape. The tail, though, will not regenerate after shedding. In a Pennsylvania study it was found that one third of captured female ribbon snakes had already shed their tail while a slightly lower percentage of males lacked their tails. These data reflect a very high level of predation on this species and also indicate a increase in susceptibility of females to predators (probably while they are gravid with young).

Activity and Hibernation
Ribbon snakes are typically diurnally active but may become nocturnal in the southern parts of their geographic range especially during the hot months of summer. In the northern sections of their range, ribbon snakes hibernate during the cold winter months (October to April). Their hibernation refuges may be rocky crevices or spaces, ant mounds, crayfish tunnels, or the burrows of voles, muskrats, or other small mammal. Ribbon snakes may share their hibernaculae with other snakes species (including garter snakes, American water snakes, green snakes, and red-bellied snakes). Males emerge from hibernation before females.

Mating (the ribbon snake reaches reproductive maturity in two years) occurs in May, and the young are born in August. The ribbon snake gives birth to live young typically in litters of 3 to 26 individuals. 

Human Impact
Human development of lake shore or streamside properties has very significant impacts on ribbon snake populations. House pet predation and roadway kills also add to the overwhelmingly negative impacts of human activity and presence on this species.   

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