Ribbon Snake, Western (Thamnophis proximus)

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Description

Ribbon snakes are among the familiar group known as gartersnakes. In Wisconsin there are five different species of gartersnake. Snake watchers, called herpetologists, consider gartersnakes to be as confusing as warblers are to bird watchers.

Gartersnakes are quite similar in appearance at first glance. Most are only differentiated by carefully noting subtle differences. Individuals of the same species may even differ from place to place. Ribbon snakes differ from other gartersnakes in being extremely slender with long tails (over 27% of total length) and having immaculate white "lips". Their colors tend to be brighter than other gartersnakes. Although the two species of ribbon snakes in Wisconsin are very rare and difficult to separate, there are some differences that make a distinction possible.

The western ribbon snake is slightly longer and thinner (20 to 30 inches) then its northern counterpart. The northern ribbon snake will run from about 18 to 26 inches in total length. The background color of the two species can either be black or brown. The ribbon snakes, like all other Wisconsin gartersnakes, have three longitudinal stripes. On the western species the median stripe is bright orange or yellow with greenish white side stripes. Both species have white spots on their head, however with the western ribbon snake the spots are larger, more pronounced and often overlap. Generally, the western ribbon snake has eight white upper jaw scales, called labial scales, while the northern generally has only seven.

Distribution

The western ribbon snake ranges from Indiana across to eastern Nebraska, south to Louisiana and Texas, and into Central America.

There are records for western ribbon snakes from only five sites in the southern third of Wisconsin, most recently from the Kettle Moraine in Waukesha County. The northern ribbon snake ranges east of the Mississippi River from eastern Illinois and eastern Wisconsin northeast to lower Ontario and Maine. Historically there were six small populations in south central and eastern Wisconsin, but today there are only two known, in Sheboygan and Dane counties.

Habitat and Habits

The northern and western ribbon snakes occupy the same niche in the wild.

Northern ribbon snakes are semi-aquatic, living on the fringes of open sphagnum bogs, on moss beds or the shoreline. Swimming with the agility of a water snake, it can remain submerged for several minutes hiding beneath plants to escape predators. They generally avoid deep water despite their ability to swim well. The northern ribbon snake is also a good climber, threading its body in serpentine fashion up small trees and low bushes to bask and watch for prey.

While the northern ribbon snake prefers boggy, bushy habitats, the western ribbon snake lives on sandy floodplains at the margins of rivers, lakes and marshes. Like its northern counterpart, the western ribbon snake is noted for its quick movements and capability as a swimmer and climber.

In Illinois, ribbon snakes will sometimes migrate to nearby upland woods and bluffs, and many hibernate with rattlesnakes and other snakes in rocky crevices. Their hibernation behavior in Wisconsin is unknown.

Faster and more wary then other gartersnakes, ribbon snakes are rarely captured because they easily slip through dense vegetation. Potential predators include fish, milksnakes, mink, weasels, and raptors. The tail breaks easily if grasped, distracting the predator long enough for the snake to escape. Unlike lizards however, snakes do not regenerate this lost piece of tail.

Like other gartersnakes, only cold-blooded prey are on the ribbon snakes's menu including tadpoles, salamanders, small fish, and a variety of frogs.

Breeding Habits

Mating for both the northern and western ribbon snakes takes place after emergence from hibernation in the months of April and May. Mating occurs among snakes two years old and older. Both species are ovoviviparous, giving birth to live young which develop from eggs inside the incubating female. A brood from four to forty-two young are born in late July or August.

Current Status

Both the western and northern ribbon snakes are endangered species in Wisconsin. This is primarily due to Wisconsin being on the northern or western fringe of their range with climate being the greatest limiting factor. Plowing, irrigation, grazing and water pollution are hazards which come with their ecological territory. Careful wetland preservation is essential if Wisconsin is to preserve this thin strand of life.

Excerpt from THE ENDANGERED AND THREATENED VERTEBRATE SPECIES OF WISCONSIN

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Status: State Endangered (1979).

Occurrence: In Wisconsin, known from only 5 sites in southern third of state.

Aid to ID: A 20-30 inch (50-75cm) long, slender gartersnake. Tail more than 1/4 of total length. Three longitudinal stripes on black or dark brown ground color. Median stripe often bright orange or yellow. Lateral stripes greenish. White "lips". Differ from Northern Ribbon Snakes in that parietal spots touch or are fused. They have 8 supra-labials vs. 7 for the northern. The area ventral to the lateral stripe is black.

Habitat: Vicinity of streams, lakes and marshes. Often in water-edge vegetation. In Wisconsin, they seem to prefer sandy floodplains near marshes.

Food Habits: Only eat cold-blooded prey. Prefer tadpoles and newly metamorphosing frogs and toads. Also eat salamanders and fish.

Natural History:

Active: April to October. Primarily diurnal, but nocturnal in hot weather. Semi-aquatic. Good swimmers.
Hibernation: Unknown in Wisconsin. May hibernate with other snakes.
Reproduction: Mature at 2 to 3 years. Mate in May. Ovoviviparous; 4 to 27 (avg. 13) young born in late July through August.

Management Considerations: Scarcity in Wisconsin primarily due to being on northern fringe of range. Extremely sensitive to human modification of habitat - disappear rapidly after cultivation. Also threatened by water pollution, irrigation, and loss of wetlands. This gartersnake also needs better documentation to determine the range of habitats used in Wisconsin. In hand identification is necessary in order to distinguish it from the northern ribbon snake and other gartersnakes.

See Also:
Living with Snakes

Information compiled from publications ER-515 92REV and ER-091.

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