Thamnophis sirtalis
Common Gartersnake / Couleuvre Rayée
The Gartersnakes, and other live-bearing, harmless snakes, which were included
within the Family Colubridae, have recently been placed in the Family Natricidae.
Description
The Common Gartersnake is highly variable in colour but tends to be black with
three stripes: one down the back and one on each side. The stripes are usually yellow.
The side stripes are confined to the second and third scale rows. It can grow to
over a meter in length.
Confusing Species
Depending upon the area, the Common Gartersnake can be confused with other species of
gartersnake. In British Columbia, there are two other Gartersnakes. The
Wandering Gartersnake has a black stripe, but has
dark spots. The Northwestern Gartersnake
can be quite similar, but is generally brown, rather than black. From Alberta to
Manitoba, the other confusing species is the Plains
Gartersnake, but it has squarish black spots as well as the stripes. In southern
Ontario, Butler's Gartersnake looks very
similar, but the side stripes are on the second, third and fourth scale rows. There
is also the Ribbonsnake, which is quite
similar to the Common Gartersnake. Its side stripes are only on the third and fourth
scale rows.
Distribution
The Common Gartersnake is the most widely distributed reptile in Canada -- it is found in
every province, with the exception of Newfoundland, as well as the southern part of the
Northwest Territories. There are several subspecies in Canada:
Several subspecies of T. sirtalis occur across almost all of the US, with the
exception of the driest areas in the southwest.
Habitat
The Common Gartersnake is found in a wide variety of
habitats from forests to farmlands. It also occurs in many urban areas. It is usually
found near wetlands of some sort.
Reproduction B
reeding generally occurs in the spring, soon after emerging from hibernation, but it
can also occur in the fall. In some areas, it is possible to see many snakes involved in
mating
frenzies near hibernation sites. Females typically give birth to 10-30 live young
in mid-summer. Up to 85 young have been reported from one female! The young are 13-23
cm at birth and mature in 2-3 years.
Natural History
The Common Gartersnake is the most commonly encountered snake in most parts of its
range. It has adapted well to human modification of the landscape. It is active
during the day and is commonly seen in moist areas where it hunts frogs, toads,
salamanders and earthworms. Small fish and mice are also eaten. The Common Gartersnake
hibernates underground in
burrows,
rock outcroppings, or the
foundations of old
buildings. In some areas, hundreds or even thousands of snakes will hibernate
in the same location.
Conservation Concerns
The Common Gartersnake is widespread and abundant in Canada. Aside from loss of
wetlands, the greatest threat to this snake is likely traffic mortality. Many
snakes are drawn to warm roads in the evening and are killed by passing cars.
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