(Thamnophis sauritus septentrionalis)
Other names: northern ribbon snake, eastern ribbonsnake, eastern ribbon snake
The gartersnakes, and other harmless snakes that bear live young, were included in the family Colubridae but recently have been placed in the family Natricidae.
The northern ribbonsnake is a subspecies of the wider-ranging eastern ribbonsnake (Thamnophis sauritus).
The northern ribbonsnake is black with three yellow stripes: one down the back and one on each side, on the third and fourth scale rows. It has a distinct white crescent in front of the eye, a white chin and a whitish yellow belly. This species is long and narrow, and the tail makes up approximately one-third of its total length. Northern ribbonsnakes can grow to almost a metre in length but are usually considerably shorter.
The northern ribbonsnake is very similar to the eastern gartersnake, Butler’s gartersnake and red-sided gartersnake. Those three species lack the white crescent in front of the eye, their chin is more yellow than white, and the transition between the light-coloured chin and the dark head is less distinct than in the northern ribbonsnake. Compared with those species, the northern ribbonsnake is more slender and has a longer tail. The lateral (side) stripes on the eastern gartersnake are confined to the second and third scale rows, and the lateral stripes on the Butler's gartersnake are on the third and part of the second and fourth scale rows. The red-sided gartersnake is found only in northwestern Ontario. The northern ribbonsnake may be mistaken for a queen snake, which also has two yellowish lateral stripes, but the queen snake has several faint dark stripes rather than a yellow stripe down the back.
The northern ribbonsnake is semi-aquatic and is almost always found close to water, such as wetlands and the shorelines of lakes and rivers. The wetland and shoreline habitats that ribbonsnakes inhabit are generally near forests, and this species tends to be absent from regions with little to no forest cover. The species may rely on forested areas to provide upland habitats that it uses for overwintering and birthing sites.
Northern ribbonsnakes breed in the spring after emerging from hibernation. As in all members of the genus Thamnophis, females do not lay eggs but give birth to live young. Females produce from three to 26 young, although five to 12 is more common. The young are 18 to 23 centimetres long at birth and reach maturity in two to three years.
Northern ribbonsnakes spend much of their time in or near water, where they feed primarily on amphibians, especially frogs. Ribbonsnakes bask along shorelines in the vegetation, on logs or, occasionally, in low shrubs. When startled, these snakes often move into the water, where they can elude most predators. Ribbonsnakes hibernate underground in animal burrows or rock outcroppings.
Threats & Trends
The loss of most wetland habitat in southern Ontario is the primary reason for the decline of this species, and ongoing habitat loss continues to threaten it. Northern ribbonsnakes no longer occur throughout much of southern Ontario where wetlands and forests have been converted to agricultural uses. Pollution has been shown to have severe negative effects on amphibian populations, and the loss of local amphibian populations may cause the decline or disappearance of ribbonsnakes. Road mortality and illegal collection are other threats to this species.
Current Status & Protection
The northern ribbonsnake is currently listed as Special Concern under the Ontario Endangered Species Act, 2007 and Special Concern under the federal Species at Risk Act. The species has also been designated as a Specially Protected Reptile under the Ontario Fish and Wildlife Conservation Act. These acts offer protection to individuals and their habitat. The habitat of this species is further protected in Ontario by the Provincial Policy Statement under the Planning Act. The International Union for Conservation of Nature lists the global status of the northern ribbonsnake as Least Concern. The species’ status was last confirmed in January 2010. Additional detail about legal protection for species at risk in Ontario is available on our Legal Protection page.
Learn more about reptile and amphibian conservation and what you can do to help these species on our Reptile and Reptile and Amphibian Stewardship page.
Ontario range (click to enlarge)
The northern ribbonsnake occurs in two disjunct populations in Canada. The larger population is in southern Ontario and a small part of Quebec, and the second, smaller population in Nova Scotia. This subspecies of the eastern ribbonsnake occurs throughout the eastern United States, south to Indiana and west to Wisconsin.