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 Butler’s gartersnake (Thamnophis butleri) is the smallest of Ontario’s four members of the genus Thamnophis and grows to only 69 centimetres in total length, though typically it is less than 50 centimetres long. It is brown with three yellow stripes: one down the back and one on each side, on the third and part of the second and fourth scale rows. Occasionally a melanistic form of this species (with a black, unstriped back) occurs, though not as commonly as melanistic eastern gartersnakes. The chin and belly of the Butler’s gartersnake are yellowish. This species has a smaller head than the eastern gartersnake, making the neck less obvious.
The Butler’s gartersnake is very similar to the eastern gartersnake, red-sided gartersnake and northern ribbonsnake. Those three species have larger heads and a more pronounced neck than the Butler’s gartersnake. The lateral (side) stripes on the eastern gartersnake are confined to the second and third scale rows. The lateral stripes on the northern ribbonsnake are on the third and fourth scale rows. The northern ribbonsnake also has a distinct white crescent in front of the eye, is more slender than the garternakes and has a longer tail. The red-sided gartersnake is found only in northwestern Ontario, while the Butler’s gartersnake occurs only in southwestern Ontario. This species may be mistaken for a queen snake, which also has two yellowish lateral stripes. The queen snake, however, has several faint dark stripes rather than a yellow stripe down the back.
Historically, the Butler’s gartersnake occurred in prairie habitats but can now be found in fields, wetland edges and other grassy areas. Like the eastern gartersnake, this species inhabits urban and agricultural areas. It is frequently found under cover, such as boards or rocks.
View an interactive map of the known ranges of Butler’s gartersnakes in Ontario.
Butler’s gartersnakes breed in the spring, soon after emerging from hibernation, and the live young are born in midsummer. Females typically give birth to eight to 10 live young, though up to 16 young have been reported from one female. They are roughly 15 centimetres in length at birth.
Butler’s gartersnakes feed primarily on earthworms but also eat insects and frogs. These snakes can move very quickly in long grass, although they move very awkwardly – with a great deal of “side-winding” – in non-vegetated areas. In the United States, this species overwinters in animal burrows; in Ontario, it has been observed to use crayfish burrows.
Other names: Butler’s garter snake, Eutaenia butleri
Threats and Trends
The extremely limited distribution of the Butler’s gartersnake makes it vulnerable to extinction. In Ontario, the range of this species has been reduced as a result of habitat loss, primarily due to agriculture. Although very small, the Canadian portion of this species’ range comprises a significant percentage of its global distribution. As such, conserving the Butler’s gartersnake populations in Ontario is critically important to the continued survival of this species. Despite this, the new Detroit-Windsor International Crossing project is being permitted to destroy a significant portion of this species’ habitat.
Current Status and Protection
The Butler’s gartersnake is currently listed as Endangered under the Ontario Endangered Species Act, 2007 and Threatened 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 Butler’s gartersnake as Least Concern. The species’ status was last confirmed in 2007. 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 Amphibian Stewardship page.