Butler's Gartersnake Thamnophis butleri - Endangered

Adult from Michigan

Identification: Butler's gartersnakes are small, striped snakes that are easily confused with their much more common and widespread relative: the eastern gartersnake. Most Butler's gartersnakes are dark brown in color with white to yellow dorsal and lateral stripes. This diminutive snake rarely exceeds two feet (60 cm) in length and reaches maturity at just over a foot (35 cm) in length. Their head is notably smaller than other Thamnophis and the neck is indistinct.

Similar Species: Eastern gartersnakes are easily confused with this species and are much more likely to be encountered in Indiana. There is a notable size difference between the two species and any snake over two feet (65 cm) long is almost certainly an eastern gartersnake. Though eastern gartersnakes are larger and have a more distinct head and neck, the most reliable way to differentiate the two species is by determining which scale row the lateral stripes overlay. In sirtalis, the lateral stripes fall on the second and third row of scales (counting up from the underbelly) whereas the stripes overlap the third and fourth scale rows in butleri. Eastern ribbonsnakes are similar in coloration and pattern, but are a long and slender snake by comparison, with a much longer tail.

Distribution: Butler's gartersnakes are apparently rare in Indiana, known from only a few scattered localities in northeastern quadrant of the state. They are usually found in open, wet meadows and marshes and may use heavily disturbed sites such as abandoned lots and railroad right of ways.

Distribution Map
Distribution map of Butler's Gartersnake (Thamnophis butleri)