Ribbon Snake, Northern (Thamnophis suaritus)

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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: Wisconsin is the northwest limit of their range in the U.S. Historically, six small populations were known to occur in south-central and eastern Wisconsin. Now there are only two known populations. '

Aid to ID: An extremely slender gartersnake. Up to 1/3 of total length of 18-26 inches is tail. Has three bright yellow to white longitudinal stripes on brown or black ground color and white "lips." Distinguished from Western Ribbon Snake in that parietal spots (spots located on top of head behind eyes), if present, don't overlap. They typically have 7, rather than 8, supralabial (lip) scales. The area ventral to the lateral stripe is brown.

Habitat: Appear to require abundant sunlight and low, dense vegetation (eg. leatherleaf, blueberry and cranberry) near quiet, shallow, permanent water. Prefer open sphagnum bogs, but also use sedge meadows and marshes around lakes and ponds.

Food Habits: Exclusively eat cold-blooded prey - primarily frogs and salamanders, but also fish, caterpillars and newts.

Natural History:

Active: April to October. Primarily diurnal. Semi-aquatic. Agile swimmers and good climbers. Alert and quick, but rarely bite.
Hibernation: Unknown in Wisconsin. May hibernate with other snakes.
Reproduction: Mature at 2-3 years. Breed April to May. Ovoviviparous; give birth to 3 to 26 young (avg. 10) in late July to August.

Management Considerations: Scarcity in Wisconsin primarily due to being on northern and western fringes of range. Loss of wetlands, plowing, irrigation, water pollution and vehicular traffic are additional threats. The identification of existing populations may help us understand the requirements of this species. Positively identifying gartersnakes requires in hand observation. Specimens that are questionable should be held for identification by a herpetologist.

See Also:
Living with Snakes

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

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