Western Yellow-bellied Racer
Coluber constrictor mormon
Western Yellow-bellied Racer
Coluber constrictor mormon
Western Yellow-bellied Racers are long, slender snakes with smooth scales, and, as their name suggests, they are incredibly speedy. Adult Racers range from 50 cm to up to 2 m, although most individuals are less than 120 cm. They are uniformly coloured on the dorsal surface in blue-grey to light olive green, with a bright to pale yellow belly that gives them their name. Juveniles are light brown or tan with dark patterning that helps camouflage them from predators in their early years.
Listen to the Indigenous words for “snake” here!
With large eyes and bright yellow bellies, adult Western Yellow-bellied Racers are distinct in that they are the only large, unpatterned, smooth snake in British Columbia. However, juvenile Western Yellow-bellied Racers have patterning that may lead to them being confused with juvenile Western Rattlesnakes or Great Basin Gophersnakes. Western Rattlesnake juveniles have vertical pupils, triangular heads, and at least one segment of a rattle on their tail. Great Basin Gophersnakes have distinct barring running down the body from the eye and lack the dark patterning on the head found in Racer juveniles.
Western Yellow-bellied Racer (Juvenile)
Western Rattlesnake
Great Basin Gophersnake
Western Yellow-bellied Racers are found along the west coast of North America from British Columbia to southern California, and east to Idaho, Montana, and Colorado. In British Columbia they are found in the arid valleys of the southern interior including the Thompson, Okanagan, Fraser, and Similkameen
Western Yellow-bellied Racers hibernate throughout the winter months in holes and hollows, usually within rock, that dip below the freezing line on south-facing slopes. Racers may overwinter in the same dens as other snake species like Great Basin Gophersnakes, Western Rattlesnakes, and Gartersnakes, but they may also den individually or use different dens every year. During the active season, Western Yellow-bellied Racers occupy a variety of habitats including grasslands, savannah, open woodlands, and rocky shrub-steppe. Typically, Racers prefer open habitats with plenty of rock crevices, mammal burrows, rocks, or logs to use as retreat sites and for thermoregulation. Western Yellow-bellied Racers appear to be fairly particular about their nesting sites, so much so that females will travel several hundred meters to lay their eggs at a specific site.
Western Yellow-bellied Racers mate in the spring, shortly after emerging from their overwintering dens. Females will lay anywhere from 3-12 leathery eggs in mid-summer in a sandy hole, rocky crevice, or grass root clump on a south-facing slope. Several Racers may all lay eggs in the same spot, especially if ideal nesting sites are scarce. The eggs will hatch in late August or early September, with the racers being fully independent as soon as they hatch. Male Racers reach sexual maturity after 2 years, while females reach maturity after 2 or 3 years. Western Yellow-bellied Racers may live over 20 years.
Western Yellow-bellied Racers have excellent eyesight that makes them efficient day-time predators. During the spring and early summer, adult Racers mainly eat mice, voles, small reptiles, frogs, and small bats and birds. However, as the summer progresses and insects become more plentiful, they switch from larger vertebrate prey and almost exclusively eat insects like grasshoppers and crickets. Juvenile Racers mainly eat grasshoppers, crickets, and caterpillars.
Western Yellow-bellied Racers tend to inhabit the same areas that people like to develop: dry, hot river valleys. This overlap has led to much of their historic range and habitat being altered into urban and agricultural areas. These landscape changes, combined with a very limited understanding of Racer population sizes, have led to the species being listed as Threatened in Canada. The main threat to Western Yellow-bellied Racers in Canada is continued habitat loss due to urban and agricultural development, which can easily impact Racer populations, especially when development occurs near denning habitat, as they are very limited in the distance they can travel from their dens.
Description
Western Yellow-bellied Racers are long, slender snakes with smooth scales, and, as their name suggests, they are incredibly speedy. Adult Racers range from 50 cm to up to 2 m, although most individuals are less than 120 cm. They are uniformly coloured on the dorsal surface in blue-grey to light olive green, with a bright to pale yellow belly that gives them their name. Juveniles are light brown or tan with dark patterning that helps camouflage them from predators in their early years.
Listen to the Indigenous words for “snake” here!
Similar Species
With large eyes and bright yellow bellies, adult Western Yellow-bellied Racers are distinct in that they are the only large, unpatterned, smooth snake in British Columbia. However, juvenile Western Yellow-bellied Racers have patterning that may lead to them being confused with juvenile Western Rattlesnakes or Great Basin Gophersnakes. Western Rattlesnake juveniles have vertical pupils, triangular heads, and at least one segment of a rattle on their tail. Great Basin Gophersnakes have distinct barring running down the body from the eye and lack the dark patterning on the head found in Racer juveniles.
Credit: J. Maughn
Western Yellow-bellied Racer (Juvenile)
Credit: Marcus Atkins
Western Rattlesnake
Credit: Joe Crowley
Great Basin Gophersnake
Distribution
Western Yellow-bellied Racers are found along the west coast of North America from British Columbia to southern California, and east to Idaho, Montana, and Colorado. In British Columbia they are found in the arid valleys of the southern interior including the Thompson, Okanagan, Fraser, and Similkameen.
Habitat
Western Yellow-bellied Racers hibernate throughout the winter months in holes and hollows, usually within rock, that dip below the freezing line on south-facing slopes. Racers may overwinter in the same dens as other snake species like Great Basin Gophersnakes, Western Rattlesnakes, and Gartersnakes, but they may also den individually or use different dens every year. During the active season, Western Yellow-bellied Racers occupy a variety of habitats including grasslands, savannah, open woodlands, and rocky shrub-steppe. Typically, Racers prefer open habitats with plenty of rock crevices, mammal burrows, rocks, or logs to use as retreat sites and for thermoregulation. Western Yellow-bellied Racers appear to be fairly particular about their nesting sites, so much so that females will travel several hundred meters to lay their eggs at a specific site.
Reproduction
Western Yellow-bellied Racers mate in the spring, shortly after emerging from their overwintering dens. Females will lay anywhere from 3-12 leathery eggs in mid-summer in a sandy hole, rocky crevice, or grass root clump on a south-facing slope. Several Racers may all lay eggs in the same spot, especially if ideal nesting sites are scarce. The eggs will hatch in late August or early September, with the racers being fully independent as soon as they hatch. Male Racers reach sexual maturity after 2 years, while females reach maturity after 2 or 3 years. Western Yellow-bellied Racers may live over 20 years.
Diet
Western Yellow-bellied Racers have excellent eyesight that makes them efficient day-time predators. During the spring and early summer, adult Racers mainly eat mice, voles, small reptiles, frogs, and small bats and birds. However, as the summer progresses and insects become more plentiful, they switch from larger vertebrate prey and almost exclusively eat insects like grasshoppers and crickets. Juvenile Racers mainly eat grasshoppers, crickets, and caterpillars.
Threats
Western Yellow-bellied Racers tend to inhabit the same areas that people like to develop: dry, hot river valleys. This overlap has led to much of their historic range and habitat being altered into urban and agricultural areas. These landscape changes, combined with a very limited understanding of Racer population sizes, have led to the species being listed as Threatened in Canada. The main threat to Western Yellow-bellied Racers in Canada is continued habitat loss due to urban and agricultural development, which can easily impact Racer populations, especially when development occurs near denning habitat, as they are very limited in the distance they can travel from their dens.
Did You Know?
The Western Yellow-bellied Racer is the only snake in British Columbia that heavily preys on insects! Scientists have even observed them sliding their heads down blades of grass to scare crickets and grasshoppers into jumping out from their hiding places at the base of grass clumps.
Racers are very well suited to their names, they are incredibly quick, and can quite literally disappear in the blink of an eye. They are not only speedy on the ground, but they are very skilled climbers and can sometimes be found hunting in trees or bushes.