NWT Species Search

General Biology

Female Age at Maturity

Red-sided garter snakes are considered sexually mature at ~4 years of age.

References:

Longevity

Lifespan 6-12 years. Generation time estimated 5.4 years.

References:

Economic/Human Considerations

Important ecosystem functions.

References:

A103

Habitat

The species is found in a diverse range of semi-aquatic and terrestrial habitats that provide prey and a variety of microhabitats for thermoregulation and cover. The species usually inhabits fairly open areas with freshwater sources. The distribution broadly overlaps with known and potential karst areas in Wood Buffalo National Park and regionally outside of the Park. Because of this understood reliance on karst features for hibernation, and the locations of karst in the NWT, distribution in the NWT may be patchy. Temperature, moisture, and ventilation characteristics are likely important in determining the suitability of overwintering sites. Populations elsewhere, however, show that hibernation sites are not restricted to karst features. As long as they are protected from freezing, hibernation may occur in rock outcrops, slumps, rotted out channels formed by tree roots, ant mounds, beaver lodges, and even in and around human structures.

References:

Distribution

Ecozones

Boreal Plains, Hudson Plains

References:

B008

Distribution

The red-sided garter snake is the most northerly distributed reptile in North America and is at the geographic edge of its range in the NWT. They occur within a relatively small area of the southern NWT. This ecoregion has one of the mildest climates in the territory. Most of the known range in the NWT is in the area of Wood Buffalo National Park, however, they have also been observed along the Little Buffalo River, near Hay River and Fort Resolution, and as far north as the west short of the north arm of Great Slave Lake, west of Waite Island. Estimated extent of occurrence in the NWT is 8,990 km2.

Score:

References:

Number of Occurrences

There are a total of 11 known or suspected hibernacula within about 25 km of Fort Smith, NWT (including northern Alberta); four occur in the NWT, six occur in Alberta, and one occurs on the NWT-Alberta border. Based on observations, it also seems possible that hibernacula also exist near Hay River and along the southern shores of Great Slave Lake

Score:

References:

Area of Occupancy

Approximately 12 km2 in the NWT based on known hibernacula.

Score:

References:

Population

Population Size

Unknown, probably small to medium 1,000 - 10,000 (M. Fournier). Observations in the NWT are uneven, with some areas having only individual records of observations. Population information, apart from incidental observations, is unavailable for red-sided garter snakes in the NWT.

Score:

References:

Trends

Unknown

References:

Threats

Mortality as a result of traffic collisions is typically considered the most serious plausible threat to red-sided garter snakes. Reports of roadkill near hibernacula in and near the NWT have been described as 'many', although no systematic tracking of road-related mortalities occurs in or near the NWT. In snake populations elsewhere, road mortality has been associated with population declines and increased probability of local extinction. Drought and fires have been prominent concerns in much of the southern NWT in recent years. Rainfall reached near historic-to-historic lows in 2023 in the range of NWT red-sided garter snakes. Drought conditions continue into 2024. These conditions are likely to affect freshwater wetland summering habitat, as well as their primary prey, amphibians. The intensity, speed, and extent of the 2023 fire season compounds concerns surrounding drought and impact to habitat. Documented dates of birth and return to the hibernacula coincide with the period during which the 2023 fires were moving through the range. Several diseases may also have the potential to affect red-sided garter snake populations in the NWT. Lastly, intentional killing of snakes by people is known to occur in the NWT and aggregation at hibernacula can make red-sided garter snakes particularly vulnerable to this kind of persecution. The population level impact of these threats is currently unknown.

Score:

References:

Intrinsic Vulnerability

The red-sided garter snake is considered opportunistic and adaptable, with flexible habitat requirements and the capacity for long-distance movement (travel of 20 kms has been recorded). They are ectotherms and cannot survive freezing for very long. They have adaptations and behaviours to maintain their body temperature, including hibernation, basking, and sheltering. For the NWT population, spring emergence is later, spring courting and mating period is shorter, sexual maturity occurs later, mating occurs less frequently, litters are smaller, the size of individual newly born snakes is larger, and growth rates are slower than in southern populations. Availability of suitable habitat is possibly limiting.

Score:

References: