Description
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.
Confusing Species
Butler's Garter Snake is very similar to both the Common Garter Snake and the Ribbon Snake. The placement of the
side stripes is diagnostic in these closely related species. In
Butler's Garter Snake 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 Garter Snake and the 3rd and 4th rows of
the Ribbon Snake.
Distribution
Butler's Garter Snake is limited to parts of
southwestern Ontario. It is most common in extreme southwestern
Ontario, but there are a few other populations slightly farther
north. These disjunct populations imply that at one time Butler's
Garter Snake 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.
Habitat
This garter snake 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.
Reproduction
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.
Natural history
Butler's Garter Snake feeds mainly on earthworms. It
also eats insects and even small frogs. Butler's Garter Snake 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.
Conservation Concerns
Although not widespread, where it occurs, Butler's
Garter Snake may be the most common snake. Because of the limited
range in Canada, it is more sensitive than wide-ranging species.
The Canadian portion of the range is not just the northern fringe
of its distribution, as it comprises a significant percent of the
entire range. Butler's Garter Snake is designated Vulnerable in
Canada by COSEWIC.
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