Butler's Gartersnake / Couleuvre à Petite Tête
The Gartersnakes, and other live-bearing, harmless snakes, which were included
within the Family Colubridae, have recently been placed in the Family Natricidae.
The smallest of Ontario's three members of the genus Thamnophis. It grows
to only 69 cm in total length, but typically is less than 50 cm. It is a brown snake
with two yellow or orange side stripes and a stripe down the center of its back.
Butler's Gartersnake is very similar to both the
Common Gartersnake and the Ribbonsnake.
The placement of the side stripes is diagnostic in these closely related species.
In Butler's Gartersnake the stripes occupy the 3rd scale row and part of the 2nd
and 4th row. The stripe is confined to the 2nd and 3rd scale rows of the Common
Gartersnake and the 3rd and 4th rows of the Ribbonsnake.
Butler's Gartersnake is limited to just three small, widely separated areas in
southwestern Ontario. These disjunct populations imply that at one time Butler's
Gartersnake may have been more widespread in Ontario, during an earlier, warmer
climate. Outside of Canada, it also has a limited distribution. Its range is
centered on the southern Great Lakes and it is not found south of Ohio.
This Gartersnake tends to be associated with grassy or prairie-like areas. It may
make use of vacant lots in urban or suburban areas. Although frequently found under
cover such as boards or rocks, this may simply be because they are virtually
impossible to locate when hunting in grass.
Mating occurs in the spring and the young are born in the summer -- females do not
lay eggs. Up to 16 offspring have been recorded although 8-10 are more common.
Newborns are roughly 15 cm in length at birth.
Butler's Gartersnake feeds mainly on earthworms. It also eats insects and even
small frogs. Butler's Gartersnake can move very quickly in long grass although
it is very awkward in unvegetated areas, where it moves with a great deal of
"side-winding." It is less active during the day. It is unknown where individuals
overwinter in Canada, but in the US, individuals have made use of animal burrows.
The extremely limited distribution of Butler's Gartersnake make it more vulnerable than
wide-ranging species. The range has contracted as a result of habitat loss, primarily
due to agriculture. The Canadian mortion of the range is not just the northern fringe
of its distribution, as it comprises a significant percent of the entire range. Given
its limited distribution, Butler's Gartersnake is designated Threatened in Canada by