Red-Sided Gartersnake (Thamnophis sirtalis parietalis)
Of the six species of snake to call Alberta home, the red-sided gartersnake has the largest range and is the species most likely to be found in the Edmonton region. These harmless snakes usually make a hasty retreat when approached by humans. Often, only the tip of their tail will be seen disappearing into the brush.
Photo by Doris May
Why they Matter to Us
Red-sided gartersnakes are part of a healthy ecosystem. They act as natural pest control by consuming agricultural pests such as insects and slugs.
How You Can Help
Support protected areas in the Edmonton region (such as EALT). You can donate or volunteer your time to help with conservation efforts.
Road mortality is the largest threat to this species, especially when they emerge from hibernation in large masses in the spring. Stay alert while driving and, if safe to do so, slow down or stop to allow dispersing snakes to cross the road safely.
How to Identify
Identify by Sight
Photo by Doris May
To identify the red-sided gartersnake, look for these distinguishing features:
Slender snake reaching 100 cm in length.
Usually dark green or black, but colouration can vary.
Three yellow stripes: one on the back (dorsal stripe) and one on each side of the body (lateral stripes).
Red or orange markings are often present between the stripes.
Where to Find
These snakes are found in the boreal forest, foothills, and parkland regions of Alberta and inhabit a variety of habitats, including forests, fields, wetlands, and rocky areas. They are often seen in urban areas, usually close to natural areas like parks and ravines. Red-sided gartersnakes hibernate below the frost line during the winter in dens called hibernacula (singular = hibernaculum). Mammal burrows, crevices in rocks, or man-made structures may be used as hibernaculum sites.
Life Cycle
Photo by Hil Reine
Red-sided gartersnakes overwinter in large groups. Mating typically takes place in the spring shortly after they emerge from hibernation, but they may also mate in the fall. Many males may compete for few females in mating frenzies close to hibernacula. Females give birth to live young in the summer, and the young will reach maturity after 2-3 years.
Following mating, gartersnakes disperse to feeding grounds, which may be many kilometers away. They will return to the same hibernaculum in the fall year after year. Since suitable hibernaculum sites are relatively rare, preservation of existing hibernacula is vital to the survival of red-sided gartersnakes.
Food Chain
Red-sided gartersnakes feed on a variety of prey, including amphibians, leeches, earthworms, slugs, insects, small fish, small mammals, and sometimes small birds and bird eggs.
Gartersnakes are prey for a variety of birds and mammals, including coyotes, shrews, hawks, and crows.
Fun Facts
It is illegal to keep a gartersnake as a pet in Alberta without a permit.
Females may give birth to up to 100 live young, though clutch sizes of 10-30 are more typical.
A single hibernaculum may house hundreds (or sometimes thousands) of snakes during the winter.
Red-sided gartersnakes are harmless to humans but may excrete a very smelly musk if handled or disturbed.