The Western terrestrial garter snake is a mildly venomous colubrid snake found in western North America. It is an immensely variable species, and even the most experienced herpetologists have trouble when it comes to identification. Most individuals have a yellow, light orange, or white dorsal stripe, accompanied by two stripes of the same color, one on each side. Some varieties have red or black spots between the dorsal stripe and the side stripes.
Western terrestrial garter snakes are found in central British Columbia, central Alberta, and southwestern Manitoba in Canada. They can be found in the western United States, as far east as western Nebraska and the Oklahoma Panhandle. An isolated population occurs in Baja California, Mexico. These snakes live in a wide variety of habitats, including grasslands, shrubland, woodlands, and coniferous forests. They also often occur in wetlands and areas near lakes, rivers, streams, and ponds.
Western terrestrial garter snakes are primarily terrestrial, although populations in the Great Basin and the Rocky Mountains are semi-aquatic and feel home both on land and in the water. These snakes are generally solitary and diurnal; in the morning they usually bask in the sun and closer to the middle of the day come out to hunt. When hunting, Western garter snakes use chemical and visual senses both on land and in water. They search and attack their prey by craning, cruising, and diving. In the evening they return to their shelters where they also hide from the mid-day heat. During cold months of the year, Western terrestrial garter snakes hibernate in their dens, usually communally.
Western terrestrial garter snakes are carnivores and their diet relies heavily on the prey available in the environment and thus varies due to geographical differences. There are two main variants that are most prevalent: coastal and inland populations. The diet of coastal populations mainly includes terrestrial prey such as slugs, salamanders, small mammals, and lizards. In contrast, inland populations indulge in a semi-aquatic diet containing frog and toad larvae, leeches, and fish.
Western terrestrial garter snakes are polygynandrous (promiscuous), meaning that both the males and females mate with multiple partners. They breed in spring after hibernation. Females do not lay eggs, but instead are ovoviviparous and give birth to live young. Broods of 8 to 12 young are usually born in August and September. They are independent at birth and don't require further parental care.
Western terrestrial garter snakes don't face any major threats at present. However, locally they suffer from habitat loss, the use of pesticides and are often killed on roads. Young snakes often die from winter starvation.
According to the IUCN Red List, the total population size of the Western terrestrial garter snake is unknown but certainly exceeds 100,000 individuals. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and its numbers today are stable.