BC Conservation Data Centre: Species Summary
Coluber constrictor
North American Racer
| Scientific Name: | Coluber constrictor Linnaeus, 1758 | ||||||||||
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| Scientific Name Synonyms: |
Coluber constrictor mormon
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| English Name: | North American Racer | ||||||||||
| English Name Synonyms: |
Racer
Western Yellow-bellied Racer |
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| Classification / Taxonomy | |||||||||||
| Scientific Name - Concept Reference: | Pyron, R. A., F. T. Burbrink, and J. J. Wiens. 2013. A phylogeny and revised classification of Squamata, including 4161 species of lizards and snakes. BMC Evolutionary Biology 29:131. | ||||||||||
| Classification Level: | Species | ||||||||||
| Taxonomy Comments: | The CDC reports on this element at the species level, as only one subspecies occurs within the province (Coluber constrictor mormon). | ||||||||||
| Species Group: | Vertebrate Animal | ||||||||||
| Species Code: | R-COCO | ||||||||||
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| Conservation Status / Legal Designation | |||||||||||
| Global Status: | G5 (Feb 2016) | ||||||||||
| Provincial Status: | S2S3 (Mar 2018) | ||||||||||
| BC List: | Blue | ||||||||||
| Provincial FRPA list: | Y (Jun 2006) | ||||||||||
| Provincial Wildlife Act: | |||||||||||
| COSEWIC Status: | Threatened (Nov 2015) | ||||||||||
| COSEWIC Comments: | Status applied to Coluber constrictor mormon. | ||||||||||
| SARA Schedule: | 1 - Threatened (Feb 2023) | ||||||||||
| SARA Comments: | Ssp. mormon only. | ||||||||||
| General Status Canada: | 3 - Sensitive (2005) | ||||||||||
| Ecology & Life History | |||||||||||
| General Description: | Upper surface of adults varies from black (e.g., northeastern U.S) to plain brown or olive (most of western and central U.S.), with a spattering of white, yellowish, buff, or pale blue in some parts of the south-central United States; upper scales smooth (unkeeled); belly black (e.g., northeastern U.S.) to plain yellow or cream (western and central U.S.); eyes large; anal scale divided; nostril bordered by two separate scales; usually 15 dorsal scale rows just anterior to the vent; lower preocular scale (lowermost scale in front of the eye) wedged between upper lip scales. Total length up to around 190 cm in the northeastern U.S., much smaller (usually less than 90 cm) in the west. Hatchling: upper surface with numerous brown blotches on a paler background; eyes relatively huge. Source: Hammerson (1999). | ||||||||||
| Subspecies Comments: | The Western Racer (C. c. mormon) is the only subspecies of Racer in BC. It was recently treated as its own species (Collins 1991) but has since been recognized as just a subspecies (Crother et al. 2000). | ||||||||||
| Identification Comments: | Racers are slender and sleek, sometimes growing to over a metre in length. They have relatively large heads and very large eyes with round pupils. The dorsal surface has no pattern in adults and is a olive-green. The dorsal skin neonates and yearlings is patterned with a series of saddle markings down its back, resembling a Gophersnake but is easily distinguished by not having any pattern on the tail and the eyes are much larger. The dorsal suface is yellow. Nightsnakes might also be confused with juvenile Racers but they have vertical eye pupils and short tails. Adult Racers should not be confused with Rubber Boas, which have no dorsal patterns but have stout bodies, blunt tails, and very small eyes. | ||||||||||
| Global Reproduction Comments: | Eggs laying occurs in June or early to mid-July in most areas. Eggs laying peaks early to mid-June in southern Michigan (Rosen 1991), late June or early July in Utah/Colorado. Clutch size is usually 5-28, averages higher in the east than in the west; mean clutch size about 6 in Utah, 12 in Kansas, 15 in Michigan (Rosen 1991). Eggs hatch in about 6-9 weeks, generally in August or early September. Females become sexually mature in 3 years in Utah, 2-3 years in Kansas, 2 years in Michigan (Rosen 1991). Sometimes this snake nests communally. | ||||||||||
| Provincial Reproduction Comments: | Breeding occurs during May in the summer range when adult snakes (>3-4 years old) from different dens are most likely to be in contact with each other. Adult females reproduce annually or biennially, depending on their condition and are adversely affected by drought. Clutch size is dependent on female size and condition with an average of 6 eggs in BC, but as many as 12 has been reported (COSEWIC 2004). Egg laying occurs in June or July and hatchlings emerge in 40 to 60 days (COSEWIC 2004). | ||||||||||
| Global Ecology Comments: |
Home range size was estimated at 1.4 ha for nongravid females in Utah (Brown and Parker 1976), about 10 ha in Kansas (Collins 1982). In South Carolina, summer home range was 5-21 ha (mean 12 ha); movement on active days was 74-135 m (mean 104 m); home ranges overlapped (Plummer and Congdon 1994). Population density was estimated to be 0.65/ha in Utah (Brown 1973), up to about 15/ha in Kansas. Estimated adult annual survivorship was 79% in Utah, 62% in Kansas, 54% in Michigan (Rosen 1991). When confronted by a person, racers, like many harmless snakes, sometimes vibrate the tail. In dry vegetation, this may produce a sound similar to that make by a rattlesnakes rattle. |
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| Provincial Ecology Comments: | Racers inhabit most of the grassland and shrub-steppe ecoysystems of the Southern Interior of the Province. Although they can be found in forested landscapes, they seem to have a preference for open habitats where their good vision can most benefit them seeking prey and their speed is unencumbered by abundant debris, especially avoiding predators. They also have a high tolerance for warm temperatures and typically avoid shade. Despite their reliance on ground travel, they are also good climbers and will seek prey in shrubs or use the branches for cover and basking perches. Racers use cover objects at night and on cool days, so suitable debris must make up part of their environment. Prey is actively hunted and consists of any small animal. There are many predators of Racers, including other snakes, raptors, mustellids, and carnivores. Egg and young survivorship is thought to be low but increases with maturity. Populations are probably quite stable between years, without anthropogenic threats. Adults are believed to have home ranges which rarely extend beyond 1km from their den. Aggregations have only been observed at dens (<5 individuals), during breeding, and young emerging from nest sites (COSEWIC 2004). | ||||||||||
| Migration Characteristics: (Global / Provincial) | |||||||||||
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Nonmigrant: Local Migrant: Distant Migrant: Within Borders Migrant: |
N / N Y / Y N / N na / N |
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| Global Migration Comments: | Migrates up to at least 1.8 km between winter hibernaculum and summer range in Utah (Brown and Parker 1976), up to at least 2.3 km (average at least 848 m) in Michigan (Rosen 1991). | ||||||||||
| Provincial Mobility & Migration Comments: | Racer movement behavioiur has been poorly studied. Communual hibernation sites have been documented but they may also use small denning features where only one or several snakes might hibernate. Racers are diurnal so they have greater opportunity to travel during spring and fall when other species of snakes are hindered by cool nights. Racers are capable of traveling at speeds of 7km/hr although they are thought to spend most of their time within 1km of their den and largest known seasonal displacement from a den is only 1.8km (COSEWIC 2004). | ||||||||||
| Habitats: (Type / Subtype / Dependence) |
Forest / Conifer Forest - Dry / Facultative - frequent use
Grassland/Shrub / Antelope-brush Steppe / Facultative - frequent use Grassland/Shrub / Grassland / Facultative - frequent use Grassland/Shrub / Meadow / Facultative - frequent use Grassland/Shrub / Sagebrush Steppe / Facultative - frequent use Rock/Sparsely Vegetated Rock / Cliff / Obligate Rock/Sparsely Vegetated Rock / Rock/Sparsely Vegetated Rock / Obligate Rock/Sparsely Vegetated Rock / Talus / Obligate |
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| Global Habitat Comments: | Habitats encompass a wide range of lowland and montane areas, including deserts, prairies, sandhills, shrublands, woodlands, forests, canyons, streamsides, and semi-agricultural areas. This snake is absent from the driest deserts and highest mountains (subalpine zones and higher). It commonly climbs shrubs and small trees. When inactive, it hides underground, in crevices, or under surface cover. Adults often hibernate communally, sometimes partly submerged in water. Eggs are laid in underground tunnels or burrows, rotting stumps, sawdust piles, or under rocks. Oviposition sites may be up to at least several hundred meters from the usual home range (Brown and Parker 1976, Iverson et al. 1995). | ||||||||||
| Provincial Habitat Comments: | Typically hibernate in fractured rock outcroppings and talus slopes on warm aspects. Forage in open habitats (e.g. grasslands, shrub-steppe) where vision is unobstructed and high body temperatures can be maintained. However, Racers have also been found in broad forested habitats with clearings suggesting they have some tolerence for this habitat structure. | ||||||||||
| Food Habits: |
Carnivore: Adult, Immature
Invertivore: Adult, Immature |
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| Global Food Habits Comments: | Diet typically includes small mammals, birds, reptiles, amphibians, and large insects. | ||||||||||
| Provincial Food Habits Comments: | Racers have one of the least restrictive diets of any BC snake species. A wide variety of invertebrates and small vertebrates are eaten. The taking of invertebrates is especially beneficial for young racers, unlike most other species of snakes that must rely on capturing small vertebrates for their first meals. Prey is bitten and then swallowed whole and alive. | ||||||||||
| Global Phenology: |
Diurnal: Adult, Immature
Hibernates/aestivates: Adult, Immature |
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| Global Phenology Comments: | Racers are inactive during cold weather and are dormant from October or November to March or April in much of the range (Hammerson 1999). They are active on bright overcast or sunny days in summer, but typically only on sunny, relatively warm days in spring and fall (Hammerson, 1987, Rosen 1991). In South Carolina in summer, racers were active on an average of 72% of days; inactive snakes usually were in ecdysis (Plummer and Congdon 1994). | ||||||||||
| Provincial Phenology: (1st half of month/ 2nd half of month) |
Jan: Present / Present
Feb: Present / Present Mar: Present / Active Apr: Active / Active May: Active / Active June: Active / Eggs present outside adult July: Eggs present outside adult / Eggs present outside adult Aug: Larvae present and active / Larvae present and active Sept: Larvae present and active / Active Oct: Active / Present Nov: Present / Present Dec: Present / Present |
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| Provincial Phenology Comments: | Racers hibernate in dens throughout the winter (mid-October through mid-March). Spring emergence is quickly followed by disperal from the den to the summer range. Breeding occurs in the summer range when adult snakes (>3-4 years old) from different dens are most likely to be in contact with each other. Racers are only active during the day and use their vision as a primary sense. | ||||||||||
| Colonial Breeder: | N | ||||||||||
| Length(cm)/width(cm)/Weight(g): | 196/ / | ||||||||||
| Elevation (m) (min / max): |
Global:
Provincial: 298 / 900 |
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| Distribution | |||||||||||
| Endemic: | N | ||||||||||
| Global Range Comment: | The range extends from southern British Columbia, southern Saskatchewan, Wisconsin, Michigan, southern Ontario, New York, and southern Maine southward in the United States to southern California, Arizona, New Mexico, Texas, the Gulf Coast, and southern Florida, and southward through northeastern, central, and southern Mexico to Guatemala and Belize (Wilson 1978, Lee 2000, Ernst and Ernst 2003, Stebbins 2003). A record for Durango, Mexico, evidently is erroneous (Webb 2001). Elevational range extends from sea level to about 2,550 meters (8,300 feet). | ||||||||||
| Authors / Contributors | |||||||||||
| Global Information Author: | Hammerson, G. | ||||||||||
| Last Updated: | Jan 28, 2010 | ||||||||||
| Provincial Information Author: | Sarell, M. | ||||||||||
| Last Updated: | Mar 14, 2008 | ||||||||||
| References and Related Literature | |||||||||||
B.C. Ministry of Environment. Recovery Planning in BC. B.C. Minist. Environ. Victoria, BC. |
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Behler, J. L., and F. W. King. 1979. The Audubon Society field guide to North American reptiles and amphibians. Alfred A. Knopf, New York. 719 pp. |
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Brown, W. S. 1973. Ecology of the racer, Coluber constrictor mormon (Serpentes, Colubridae), in a cold temperate desert in northern Utah. Ph.D. thesis, Univ. Utah, Salt Lake City. |
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Brown, W. S., and W. S. Parker. 1976. Movement ecology of Coluber constrictor near communal hibernacula. Copeia 1976:225-242. |
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Collins, J. T. 1982. Amphibians and reptiles in Kansas. Second edition. Univ. Kansas Mus. Nat. Hist., Pub. Ed. Ser. 8. xiii + 356 pp. |
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Collins, J. T. 1990. Standard common and current scientific names for North American amphibians and reptiles. 3rd ed. Society for the Study of Amphibians and Reptiles. Herpetological Circular No. 19. 41 pp. |
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Collins, J. T. 1991. Viewpoint: a new taxonomic arrangement for some North American amphibians and reptiles. SSAR Herpetol. Review 22:42-43. |
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Corn, P.S., and R.B. Bury. 1986. Morphological variation and zoogeography of racers (Coluber constrictor) in the Central Rocky Mountains. Herpetologica 42:258-264. |
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COSEWIC. 2004r. COSEWIC assessment and update status report on the Eastern and Western Yellow- bellied Racers, Coluber constrictor flaviventris and Coluber constrictor mormon in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vii + 35 pp. (www.sararegistry.gc.ca/status/status_e.cfm) |
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Crother, B. I., J. Boundy, J. A. Campbell, K. de Queiroz, D. R. Frost, R. Highton, J. B. Iverson, P. A. Meylan, T. W. Reeder, M. E. Seidel, J. W. Sites, Jr., T. W. Taggart, S. G. Tilley, and D. B. Wake. 2000. Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. Society for the Study of Amphibians and Reptiles, Herpetological Circular No. 29. 82 pp. |
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Ernst, C. H., and R. W. Barbour. 1989b. Snakes of eastern North America. George Mason Univ. Press, Fairfax, Virginia. 282 pp. |
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Fitch, H. S. 1963. Natural history of the racer Coluber constrictor. Univ. Kans. Publ. Mus. Nat. Hist. 15(8): 351-468. |
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Fitch, H. S. 1970. Reproductive cycles of lizards and snakes. Univ. Kansas Museum Natural History Miscellaneous Publication 52:1-247. |
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Fitch, H.S., W.S. Brown, and W.S. Parker. 1981. Coluber mormon, a species distinct from C. constrictor. Trans. Kansas Acad. Sci. 84:196-203. |
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Forest Practices Code. 1997. Yellow-Bellied Racer in Species and Plant Community Accounts for Identified Wildlife: Vol. 1. B.C. Minist. For. and B.C. Environ. 184pp. |
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Greene, H. W. 1984. Taxonomic status of the western racer, Coluber constrictor mormon. J. Herpetol. 18:210-211. |
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Gregory, P.T., and R.W. Campbell. 1984. The Reptiles of British Columbia. Royal B.C. Mus. Handb. 102pp. |
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Hammerson, G. A. 1982b. Amphibians and reptiles in Colorado. Colorado Division of Wildlife, Denver. vii + 131 pp. |
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Minton, S. A., Jr. 1972. Amphibians and reptiles of Indiana. Indiana Academy Science Monographs 3. v + 346 pp. |
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Nussbaum, R.A., E.D. Brodie, Jr., and R.M. Storm. 1983. Amphibians and Reptiles of the Pacific Northwest. University Press of Idaho, Moscow, Idaho. 332 pp. |
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Orchard, S.A. 1988. Species Notes for Reptiles. Vol. 3 in A.P. Harcombe, tech. ed. 1988. B.C. Minist. Environ., Lands and Parks, Wildl. Branch. 44pp. |
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Ovaska, K, S. Lennart, C Engelstoft, L. Matthias, E. Wind and J. MacGarvie. 2004. Best Management Practices for Amphibians and Reptiles in Urban and Rural Environments in British Columbia. Ministry of Water Land and Air Protection, Ecosystems Standards and Planning, Biodiversity Branch |
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Plummer, M. V., and J. D. Congdon. 1994. Radiotelemetric study of activity and movements of racers (Coluber constrictor) associated with a Carolina Bay in South Carolina. Copeia 1994:20-26. |
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Rosen, P. C. 1991. Comparative ecology and life history of the racer (Coluber constrictor) in Michigan. Copeia 1991:897-909. |
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Smith, H. M. and E. D. Brodie, Jr. 1982. Reptiles of North America. Golden Press, New York. 240 pp. |
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Stebbins, R. C. 1985a. A field guide to western reptiles and amphibians. Second edition. Houghton Mifflin Company, Boston, Massachusetts. xiv + 336 pp. |
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Vogt, R. C. 1981c. Natural history of amphibians and reptiles of Wisconsin. Milwaukee Public Museum. 205 pp. |
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Wilson, L. D. 1978b. Coluber constrictor. Cat. Am. Amph. Rep. 218.1-218.4. |
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Please visit the website Conservation Status Ranks for definitions of the data fields used in this summary report.
Suggested Citation:
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 22, 2026).