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Canadian Herpetological Society Société d'Herpétologie du Canada |
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Western Yellow-bellied Racer
Coluber constrictor mormon
Family: Colubridae
The Western Yellow-bellied Racer is a subspecies of the North American Racer (Coluber constrictor).
COSEWIC status:- Threatened
- Special Concern
- Least Concern
Description
The Western Yellow-bellied Racer is bluish grey, bluish green or brownish with a cream to yellow belly and chin. Its dorsal scales are smooth and it has a divided anal plate. Individuals can grow to almost 2 m in length. Juveniles tend to be tan or light brown and have dark patterning.
Similar Species
This species is the only large, unpatterned and smooth snake within its Canadian range. However, because of their patterning, juveniles may be confused with juveniles of Western Rattlesnakes or Gophersnake. Western Rattlesnake juveniles have vertical pupils, triangular heads and at least one segment of the rattle on the tip of the tail. Gophersnakes have distinct bars running back from the eye and the head lacks the dark patterning found on juvenile racers.
Distribution
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In Canada, the Western Yellow-bellied Racer occurs in the Thompson, Okanagan, Fraser and Similkameen valleys of southern British Columbia. This subspecies occurs throughout the western U.S. states from Washington, Idaho and Montana south to southern California and east to Colorado. The various subspecies of the North American Racer occur in BC, Saskatchewan, Ontario, throughout almost all U.S. states, in Mexico and south to Guatemala.
Habitat
The Western Yellow-bellied Racer inhabits a variety of open habitats, including grasslands, fields, savannah, woodlands and rocky habitats. Rock crevices, mammal burrows, rocks, logs and other retreat sites are important microhabitats that are used for shelter and thermoregulation. This species overwinters below the frost line, often communally and with other species, in mammal burrows, rock crevices, talus slopes or anthropogenic structures (e.g. old wells, cisterns, building foundations). Females lay their eggs in rotting logs or stumps, in areas of loose sand, under rocks (such as on south-facing talus slopes) or in animal burrows.
Biology
Western Yellow-bellied Racers breed in the spring and females lay from 3–12 leathery eggs, sometimes communally. The eggs hatch in late August or early September, and the young are 20–30 cm in length. Males of this species reach maturity in two years and females in two to three years. Individuals can live for more than 20 years. The Western Yellow-bellied Racer eats insects, frogs, other snakes, small rodents and birds. Contrary to its name, this species does not constrict its food but rather swallows it alive or chews it until it is dead.
Threats
Urban and agricultural development has resulted in significant habitat loss throughout this species’ Canadian range. The expansion of the road network and associated road mortality is also a significant threat to this species, especially in the most developed parts of its range. Like many snakes, racers are often killed by misinformed people who either think they are dangerous or simply don't like snakes.