NWT Red-sided Garter Snake (Thamnophis sirtalis)
Species at Risk (NWT) Act list: No status
Federal Species at Risk Act list: No status
COSEWIC Assessment: Not assessed
NWT General Status Rank: May be at Risk
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Photo: Wood Buffalo National Park
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The garter snake is among the most widely distributed and abundant of North American reptiles. In the NWT the red-sided garter snake is known to occur only in the Fort Smith region. The karst topography in this area provides the crevices and caves necessary for hibernation. Hibernation is often communal (in large groups), possibly because suitable sites are rare. These sites appear to provide relatively warm conditions, never falling below 0°C. Water may also be necessary in the dens and these snakes sometimes submerge during hibernation.
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Mating occurs mostly in early spring when snakes emerge from hibernation but may also occur in the fall just before hibernation. The red-sided garter snake bears live young in late summer or early fall. Groups of females may give birth together at sites which offer protection from predators (for example brush or rock piles). In the north, individual females reproduce only every second year (or perhaps less often) as the summers are too short to accumulate enough nutrients for females to give birth every year. Litter size is usually small but the young are relatively large. The young are independent from birth and receive no parental care.
In summer, garter snakes are found in marshy areas where their main food sources, wood and chorus frogs, are abundant. Hibernation sites are often widely separated from summer habitats, forcing snakes to migrate long distances each spring and fall. Garter snakes are frequently killed while crossing highways and road mortality may be a serious problem, particularly in the NWT where populations are small and productivity is low.
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Photo: M. Fournier
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Identification
The background colour of this snake is black with yellow stripes, and red bars occur on the sides between the stripes. The anal scale is divided.
Distribution of the Red-Sided Garter Snake
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