Key to Striped Snakes
In Canada all vividly striped snakes with an undivided anal plate belong to the genus Thamnophis, the garter snakes. Almost all species are superficially similar and there is a high degree of geographic variation. For example, the Common Garter Snake looks quite different in eastern Canada compared with the prairies. For most species the position of the side stripe and the number of scale rows is diagnostic.
Choose the description that best fits the animal of interest.
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A. Large snake (grows to over 1 m), highly variable in colour and pattern, back and side stripes usually well-defined, side stripe confined to 2nd and 3rd scale rows, western individuals have red or orange bars between side and back stripes, 19 scale rows, British Columbia to Nova Scotia.
Thamnophis sirtalis (Common Garter Snake)
B. Large snake(grows to over 1 m), side stripes occupy 2nd
and 3rd scale rows, dark spots or light specks between stripes, 19-21 scale rows, Saskatchewan to British Columbia.
Thamnophiselegans (Western Terrestrial Garter Snake)
C. Large snake(grows to over 1 m), bright yellow or orange back stripe, side stripes cream to yellow on 3rd and 4th scale rows, double row of squarish black spots between side and back stripes, single row of black spots below side stripes, 21 scale rows, Manitoba to Saskatchewan.
Thamnophis radix(Plains Garter Snake)
D. Small snake(less than 70 cm in length), usually with red, orange or yellow back stripe, side stripes on 2nd and 3rd scale rows may be faint or absent, 17 scale rows, only found in
British Columbia.
Thamnophis ordinoides (Northwestern Garter Snake)
E. Large snake(grows to 1 m), slender, yellow to orange stripes, side stripes occupy 3rd and 4th scale rows, brownish stripe along margin of belly scales, 19 scale rows, found only in southern Ontario and a disjunct population in Nova Scotia.
Thamnophis sauritus (Eastern Ribbon Snake)
E. Small snake (less than 70 cm in length), yellow or orange side stripes occupying 3rd scale row and part of 2nd and 4th rows, 19 scale rows, head relatively small, only found in southwestern Ontario.
Thamnophis butleri(Butler's Garter Snake)
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