Great Basin Gophersnake
Pituophis catenifer deserticola
Great Basin Gophersnake
Pituophis catenifer desrticola
The Great Basin Gophersnake is the largest snake in British Columbia, reaching lengths from 90 cm up to 2 m. They have black or reddish-brown rectangular blotches down the back, contrasted on a creamy-yellow or grayish-yellow background. Individuals usually have a dark mask running from the corners of the mouth and around each eye. The head is small and only marginally wider than the neck with large eyes and round pupils. The body scales are lightly keeled giving a slightly rough feeling and textured appearance to the body.
Listen to the Indigenous words for “snake” here!
The Great Basin Gophersnake is often confused with the Western Rattlesnake. The two species may appear similar from a distance but upon closer inspection are really quite different. The Western Rattlesnake has a distinctly triangular head, vertical pupils, and the characteristic rattle at the tip of the tail. When threatened, Gophersnakes will flatten their head, hiss loudly, and vibrate their tail, creating a convincing rattlesnake imitation. Rattlesnakes however, almost never hiss, and will produce an audible and distinct buzzing sound from their rattle that cannot be imitated by a Gophersnake. Small or juvenile Gophersnakes may also be confused with the Desert Nightsnake, although the Nightsnake has vertical pupils, a distinct dark collar at the base of the head, and is a very rare sighting in British Columbia.
Credit: Joe Crowley
Great Basin Gophersnake
Credit: Marcus Atkins
Credit: Mike Cardwell
The Great Basin Gophersnake reaches the northern extent of its range in Canada, limited to the south-central region of British Columbia, although it is widely distributed in the United States where it is found in eastern Washington and Oregon, southeastern California, Idaho, Utah, Wyoming, Colorado, Arizona, and New Mexico. In B.C. its distribution is patchy, occurring in the arid interior valleys of the Okanagan, Similkameen, Kettle, Granby, Nicola, Thompson, and parts of the Fraser. The highest densities in Canada are found in the Okanagan and Thompson valleys.
The Great Basin Gophersnake (Pituophis catenifer deserticola) is the only extant subspecies in British Columbia. The Pacific Gophersnake (Pituohpis catenifer catenifer) is now considered extirpated in B.C. The Bullsnake (Pituophis catenifer savi) is often misidentified as the Great Basin Gophersnake, but is only found east of the Rockies in Alberta and Saskatchewan.
In British Columbia, Gophersnakes hibernate throughout the winter months in rocky outcropping crevices, talus slopes, or old mammal burrows that dip below the frost line. During the active season, these snakes can have very large home ranges, sometimes reaching up to 25 ha. They are associated with arid, open habitats like Bunchgrass grasslands, Sagebrush plains, and open Ponderosa forests. Within these areas, Gophersnakes require subterranean habitat, usually in the form of rock crevices, talus, or old mammal burrows, to escape the mid-summer daytime heat and for shelter from predators. They also require patches of habitat with south facing slopes covered by sand or loose rocks for females to use as nesting sites. Gophersnakes will often use different nesting and overwintering sites every year.
Great Basin Gophersnakes mate in the early spring shortly after they emerge from their overwintering dens. Males court prospective mates by lining their bodies up with a female, often biting them on the back of the neck. Gophersnakes are, laying 2-8 eggs in mid-summer, often communally with other Gophersnakes. Hatchlings emerge a few weeks later in late summer, and usually still have yolk attached to them, which is an important food source as most Gophersnakes will not eat before entering . Gophersnake nest sites are often too far away from overwintering for neonatal individuals to travel, leaving hatchlings to find old rodent burrows or rocky crevices near their birth site to overwinter in. Male Gophersnakes reach sexual maturity after a year or two, while females do not reach sexual maturity for 3-5 years and will only reproduce every other year. Great Basin Gophersnakes may live for more than 30 years.
Great Basin Gophersnakes are true constrictors, squeezing their prey until they die of asphyxiation, although they may swallow smaller prey alive. They are very active hunters, and primarily seek out in-use rodent burrows where they will prey on the inhabitants, using their burrow to digest the meal safely. They are also not averse to leaving the ground to hunt, and will often catch prey in trees or shrubs as well. In addition to small mammals like mice, voles, and squirrels, Gophersnakes also like to eat lizards and birds, and are particularly fond of bird eggs.
There is very little data on the abundance and population trends of Great Basin Gophersnakes in British Columbia. Southern B.C., where this species is most abundant, is also subject to some of the fastest rates of urban and agricultural development in the country, rapidly fragmenting and degrading Gophersnake habitat. As their hibernacula are typically located in rocky slopes, road building, landscaping, and developments that extract or blast rock can have large impacts on local populations. As Gophersnakes have large home ranges, roadways that bisect migration routes between summer foraging grounds, nesting sites, or overwintering hibernacula can cause substantial levels of road mortality. Pesticide use to control rodent populations can result in reduced prey availability, reductions of subterranean (underground) habitat for shelter and egg-laying, and potential biomagnification of harmful chemicals. Furthermore, as Gophersnakes superficially resemble rattlesnakes, they may be killed by fearful humans unnecessarily. In British Columbia, Gophersnakes are at the limit of their range, and the harsh winter climate and low reproductive capacity limit their ability to recover from population declines. For all of these reasons, the Great Basin Gophersnake has been federally listed as Threatened.
Did You Know?
Gophersnakes are non-venomous and do not have large teeth, making them virtually harmless to humans. However, if threatened they will flatten their head, inflate their body, and hiss loudly, sometimes lunging at the potential threat in an intimidating display. Watch the video below for an example of this behaviour!
Gophersnakes primarily feed on small mammals, and are very efficient predators of rodents that many farmers and landowners find to be a nuisance. Their affinity for rodents, in combination with their generally docile and non-venomous nature, make them useful neighbours on farmland or rural properties as pest control!
The Great Basin Gophersnake is often mistakenly referred to as the Bull Snake in British Columbia, which is actually the subspecies of Gophersnake that is found east of the Rocky Mountains.