Western Yellow-bellied Racer

Credit: Joe Crowley

Coluber constrictor mormon

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.

Western Yellow-bellied Racer (Juvenile)

Western Rattlesnake

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

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.

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 neonatal 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.

Conservation Status

Global: G5 (2016)

COSEWIC: T

SARA:1-T (2023)

Provincial: S2S3 (2018)

BC List: Blue

Learn more about conservation status rankings here

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.

Species Account Author: Marcus Atkins

References

B.C. Conservation Data Centre. 2010. Species Summary: Coluber constrictor. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jun 17, 2021).
B.C. Conservation Data Centre. 2018. Conservation Status Report: Coluber constrictor. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jun 17, 2021).
B.C. Conservation Data Centre. 2021. BC Species and Ecosystems Explorer. B.C. Minist. of Environ. Victoria, B.C. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jun 17, 2021).
COSEWIC. 2015i. COSEWIC assessment and status report on the Eastern Yellow-bellied Racer Coluber constrictor flaviventris and Western Yellow-bellied Racer Coluber constrictor mormon in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. xvii + 64 pp.
Environment Canada. 2015t. Management Plan for the Western Yellow-bellied Racer (Coluber constrictor mormon) in Canada. Species at Risk Act Management Plan Series. Environment Canada, Ottawa. 3 pp. + Annex
Racer Management Team Working Group. 2013. Management plan for the Racer (Coluber constrictor) in British Columbia. Prepared for the B.C. Ministry of Environment, Victoria, BC. 25 pp.
http://www.canadianherpetology.ca/species/species_page.html?cname=Western%20Yellow-bellied%20Racer
http://linnet.geog.ubc.ca/efauna/Atlas/Atlas.aspx?sciname=Coluber%20constrictor
https://www.bcreptiles.ca/snakes/westyelloracer.htm#:~:text=Racers%20are%20uniformly%20grey%20to,to%20have%20around%20th