|Common Name:||Common Ribbonsnake|
|Scientific Name:||Thamnophis sauritus sauritus|
|Genus:||Thamnophis is derived from the Greek words thamnos which means "bush" and ophio meaning "snake".|
|Species:||sauritus is derived from the Greek word sauros meaning "lizard", referring to the long lizard-like tail.|
|Subspecies:||sauritus is derived from the Greek word sauros meaning "lizard", referring to the long lizard-like tail.|
|Vernacular Names:||Little garter snake, saurite snake, slender grater snake, slim garter snake, spotted ribbon-snake, striped water snake, swift garter snake, swift streaked snake, water garter snake, yellow-headed garter snake.|
|Average Length:||18 - 26 in. (45.7 - 66 cm)|
|Virginia Record Length:||38.2 in (97 cm)|
|Record length:||38 in. (96.5 cm)|
Virginia Wildlife Action Plan Rating Tier IV - Moderate Conservation Need - The species may be rare in parts of its range, particularly on the periphery. Populations of these species have demonstrated a significant declining trend or one is suspected which, if continued, is likely to qualify this species for a higher tier in the foreseeable future. Long-term planning is necessary to stabilize or increase populations.
PHYSICAL DESCRIPTION: The adult has a dorsal pattern of three bright yellow stripes on a dark background. The lowermost stripes involve the third and fourth scale rows along both sides of the body. They have a plain yellow or greenish-yellow belly and the body is very slender with the tail comprising more than 1/4 of the total length. The juvenile is similar to the adults. The dorsal scales are keeled, there are 19 scale rows and the anal plate is undivided. Loreal and preocular scales are present. This species is about 7 inches at birth and grows to about 36 inches *1006*. In VA., max known SVL is 685 mm (27.0 in.) and max total length is 970 mm (38.2 in) *10760*. Adults are usually 18-26 inches in length *11523*. Tail length/total length ratio is 27.2-37.3% (avg. = 32.5+/-2.4, n=51) *10760*.
SCUTELLATION: ventrals 123-168 (avg. = 153.9+/-6.4, n=59); subcaudals 94-132 (avg. = 266.6+/-10.3,n=45); dorsal scales keeled; scale rows 19 at midbody; anal plate single; infralabials 10-10 (63.9%, n=61), other combinations of 9-11 (36.1%); supralabials 7-7 (84.4%, n=64), other combinations of 6-8 (15.6%); loreal scale present; preoculars 1-1; postoculars 3-3; temporal scales usually 1+2/1+2 (56.1%, n=66), other combinations of 1-3 (43.9%). Coloration and pattern: dorsum of body and tail brown to nearly black with 3 bright yellow to cream stripes; middorsal stripe may be greenish; lateral stripes occur on scale rows 3 and 4; distinct middorsal stripe extends to pareital scales on head; a variable number of dorsal body scales are partially edged in white; venter uniform, color varies from greenish to blue-gray; a brown, black, or greenish stripe is located on scale rows 1-2 on each side and extends to the lateral edges of the ventral scales; lateral edges of ventral scales without spots; chin, infralabials and supralabials white; snout and entire dorsum of head may be brownish.*10760*
SEXUAL DIMORPHISM: Adult females average longer (519.4+/-79.4 mm SVL, 401-685, n=17) than males (avg. = 373.4+/-29.2 mm SVL, 344-413, n=7) and reach a larger maximum size (females 970 mm, males 617 mm). Sexual dimorphism index is 1.39. The ratio of tail length to total length averages slightly higher in males (33.9+/-2.4%, 27.2-37.3, n=16) than females (31.9+/-2.1%, 28.3-35.9, n=35). The average number of ventrals (males 153.2+/-4.5, 147-165, n=18; females 155.0+/-5.2, 144-168, n=40) is similar between sexes, but males have a slightly higher average number of subcaudals (114.8+/-10.0, 94-132, n=14) than females (110.6+/-7.9, 99-129,n=31). Consequently, the avg. number of ventrals + subcaudals is slightly higher in males (268.4+/-11.5, 249-287, n=14) than females (265.7+/-9.8, 250-295, n=31).*10760*
JUVENILES: Juveniles are patterned as adults but are brown with bright yellow or white stripes. The brown dorsal color darkens with age. Neonates are 113-139 mm SVL (avg = 131.3+/-9.0, n=9), 161-210 mm total length (avg. = 192.8+/15.8, n=8), and weigh 0.8-1.2 g (avg. = 1.0+/-0.1, n=8).*10760*
CONFUSING SPECIES: The species most commonly confused with ribbon snakes is T. sirtalis which has lateral stripes on scale rows 2 and 3. Garter snakes have black spots on the lateral margins of the ventral scales and are not as slender as ribbon snakes.*10760*
GEOGRAPHIC VARIATION: Three regions have sufficiently large sample sizes for geographic comparisons of scutellation. The number of ventral scales varies from 148.4+/-11.7 (123-165, n=8) in the upper Piedmont, to 154.8+/-4.3 (146-163, n=30) in the lower Coastal Plain, to 157.2+/-4.9 (151-168, n=13) in the upper Coastal Plain. Subcaudal scale counts very from 107.1+/-6.9 (94-120, n=22) in the lower Coastal Plain. Subcaudal scale counts vary from 107.1+/-6.9 (94-120, n =22) in the lower Coastal Plain to 112.8+/-4.9 (104-132, n=5) in the upper Piedmont, to 119.6+/-8.2 (104-132, n=10) in the upper Coastal Plain. Like ventral scale counts, the average number of ventrals + subcaudals is lowest in the lower Coastal Plain (261.9+/-8.4, 249-275, n=22), higher in the upper Piedmont (266.0+/-9.7, 257-282, n=5), and highest in the upper Coastal Plain (277.8+/-8.1, 270-295, n=10). These values encompass the range of variation in other regions of the state. Counts of these scale characters in Virginia samples also encompass the ranges Rossman reported for samples from Maryland to N. Carolina.*10760* The population ecology of this snake has been studied only in Michigan. Carpenter found that the maximum straightline distance traveled was 278 meters, a population density of 32.2 per hectare, and that juvenile growth was about 12-24 mm per month and in adults was about 1-4 mm per month. In VA., this species appears to be more common in the Coastal Plain (45 specimens) than the Piedmont (9), Blue Ridge Mountains (1), or Valley and Ridge (4). This is probably related to the abundance of wetland habitat in the Coastal Plain and the scattered locations of suitable habitat elsewhere. Three VA. studies noting relative abundance of snake species recorded only 2 ribbon snakes.*10760*
REPRODUCTION: The female gives birth to as many as 20 live young in mid to late summer. The newborn snakes are from 7-9 inches long *1006*. In VA., the smallest mature male was 354 mm SVL and the smallest mature female was 422 mm SVL. Rossman reported that the smallest known mature female (332 mm SVL) was from Pa. In VA., known birth dates are 29 July and 6 September. N. D. Richmond found newborn juveniles on 25 July and 6 August in New Kent Co. Litter size in VA. is 6-12 (avg. = 9.6+/-1.9, n=8). Litter size throughout the range of this species is 3-26.*10760* Gravid females have been documented basking on branches over streams *11517,11523*. Near the base of a tree by an overflow stream (from a lake), Thorp observed three males attempting to breed with one female in the fall, suggesting that this species may breed in both spring and fall *11523*.
BEHAVIOR: This species is a good swimmer and has racerlike land speed. They are also good climbers and are often found in the small bushes along the waters edge. They are active and nervous and rely on quickness and the optical illusion created by their dorsal stripes to escape predators. If cornered, they will coil momentarily before fleeing. They consume frogs, salamanders, toads, small fish and leeches. One specimen had fed on a cricket frog and harvester ants. All prey is normally swallowed alive *1006*. This snake will thrash about when caught, although it will not bite. It is not easy to catch because it swiftly escapes in the grass and brush habitat. Like most natricines, it will spray musk from glands at the base of the tail and sometimes feces as well.*10760* Thorp often observes this species basking in branches and vines overhanging the water *11523*.
POPULATION PARAMETERS: The maximum known longevity of this species is 10 years and 7 months *11523*.
AQUATIC/TERRESTRIAL ASSOCIATIONS: Predators include raccoons, otters, mink, herons, kingsnakes, snapping turtles, bullfrogs, bass and pickerel *1006*. The black racer (Coluber constrictor) is also a noted predator of this species *11499,11523*.
References for Life History
Common Ribbonsnake vs. Eastern Gartersnake
*Click on a thumbnail for a larger version.