Coluber constrictor

Geographic Range

Racers occur from southern Canada to Guatemala, with considerable individual and local variation in regions where two or more subspecies intergrade (Conant and Collins, 1998). Different racer subpopulations include: The northern black racer, Coluber constrictor constrictor , ranges from southern Maine and central New York south to northern Georgia and Alabama. The blue racer, C. c. foxii , is found from Michigan, Wisconson, and Minnesota south to Ohio, Indiana, and Illinois. C. c. priapus , the southern black racer, ranges from southern Indiana and Illinois and southeastern North Carolina to central Florida and southern Arkansas. It also occurs on some of the Florida Keys. The Everglades Racer, C. c. paludicola , is found only in southern Florida. The brownchin racer, C. c. helvigularis , occurs only in the lower Chipola and Appalachicola River valleys in Georgia and Florida. C. c. latrunculus , the blackmask racer, occurs in southeastern Louisiana and adjacent Mississippi. The eastern yellow-bellied racer, C. c. flaviventris , is found from extreme southern Saskatchewan southeast through Montana, western North Dakota, east to Iowa and south to Texas. The western yellow-bellied racer is found west of the Rocky Mountains, from southern California and Nevada through through western Colorado, Oregon, and Washington and into southern British Columbia. The buttermilk racer, C. c. anthicus , ranges from south Arkansas to Louisiana, also eastern Texas. C. c. etheridgei , the tan racer inhabits Louisiana and Texas. C. c. oaxaca , the Mexican racer, has isolated populations in New Mexico, but its main range is from south Texas to Veracruz.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

Racers prefer dry sunny areas with access to cover, including old fields, open woodland, hedgerows, thickets and wood edges, sometimes damper sites such as bogs, marshes, and lake edges are also used. In the Great Lakes region, racers occupy a home area that may range in size from 2.5 acres (1 ha) to 25 acres (20 ha) depending on the productivity of the habitat (Harding, 1997). During several cold months of the year racers are inactive in shelters hidden from subfreezing temperatures. Fall and spring activity peaks are associated with movement to and from the hibernacula as well as mating and feeding (Greene, 1997).

• Habitat Regions
• temperate temperate

• Terrestrial Biomes
• savanna or grassland savanna or grassland
• chaparral chaparral
• forest forest
• scrub forest scrub forest
• mountains mountains

• Wetlands
• marsh marsh
• swamp swamp
• bog bog

• Other Habitat Features
• agricultural agricultural

Physical Description

The mature racer has very smooth shiny scales with a divided anal plate (Conant and Collins, 1998). There are 17 scale rows midbody, and 15 near the tail. The normal coloration is a very dark and uniform dorsum with variations ranging from black, bluish, gray, to olive brown. The head is narrow but still wider than the neck with very distinct brow ridges. The chin and throat areas vary from white to yellowish progressing back to a ventrum that could be black, dark gray, light blue, white, cream or yellow. The average adult length ranges from 90-190 cm. (35-75 in.) (Harding, 1997).

Juvenile racers are strongly patterned with grays, browns, and reds. The coloring fades as the snake grows older and at 30 inches all traces have usually disappeared (Conant and Collins, 1998).

Male racers can be distinguished from the female of the species in that the tail is longer with a wide base, sometimes even a bulge. The female's tail tapers abruptly from the body (Harding, 1997).

• Other Physical Features
• heterothermic heterothermic

• Sexual Dimorphism
• sexes shaped differently

Reproduction

Mating takes place in the spring, from late April until early June. In June or early July the female will lay 3-32 oval, white eggs in a hidden nest site. Suitable nest sites may be a rotted stump or log, and old mammal burrow, or a nest cavity in the leaf litter or sand (Harding, 1997). The eggs are 2.5 to 3.9 cm long and are coated with small nodules resembling hard, dry grains of salt. Hatching usually occurs in August or early September with young size approximately 7.5-14 inches (39 cm) long (Conant and Collins, 1998). Males become sexually mature in 1 to 2 years, while females mature slower, approximately 2 to 3 years. Racers have been known to oviposit communally, one case reported shows that almost 300 eggs were found in a talus slide. They originated from at least 50 racers, sharp-tailed snakes ( Contia tenuis ), ring-necked snakes ( Diadophis punctatus ), and gopher snakes ( Pituophis catenifer ) (Greene,1997).

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• sexual sexual
• oviparous oviparous

Lifespan/Longevity

In the wild, racers have been known to live over 10 years.

Behavior

Despite its common name, the racer's actual speed is about 6.5 kilometers per hour (4 mph), or about the rate of a human's brisk walk. If approached by a predator the racer's first option is usually to flee to a nearby burrow, thick vegetation, or rock crevice (Harding, 1997). Often the racer will retreat up into the bushes or low branches of a tree to escape (Conant and Collins, 1998). The racer has some interesting antipredator tactics. A startled adult will begin violent undulatory movement that is quickly changed to a rapid, graceful locomotion for 30 meters or so (Greene, 1997). If cornered, a typical racer will coil and strike while vibrating its tail nervously. The racer is non-venomous, but the slashing bite and recurved teeth may cause bleeding (Harding, 1997). If a predator comes within very close range of the racer it will coil with its head hidden and writhe, smearing scent gland secretions all over its body while alternately assuming an S-coil. If seized the racer will bite and discharge its cloacal contents while twisting its entire body so strongly that sometimes the tail is broken off. The juveniles' distinct color patterns probably mean they rely on camoflage for escape from predators rather than the tactics adults employ (Greene, 1997).

• Key Behaviors
• terricolous
• diurnal diurnal
• sedentary sedentary
• hibernation hibernation
• solitary solitary

Communication and Perception

As with many snakes, vision and olfaction are important percptual channels for racers.

• Perception Channels
• visual visual
• tactile tactile
• chemical chemical

Food Habits

Racers are carnivores. They have very broad diets. Juvenile racers eat mainly insects , spiders , small frogs , small reptiles (including lizards and snakes and their eggs) and young rodents and shrews . As racers grow, they take larger prey as well, including nestling birds and their eggs, other mammals as large as squirrels and small cottontail rabbits , small turtles and larger snakes (Greene, 1997). Their food is not constricted as the name would imply, instead a loop of the snake's body is thrown over the struggling victim, pressing it down so that it can be swallowed (Conant and Collins, 1998).

• Primary Diet
• carnivore carnivore
  • eats terrestrial vertebrates
  • insectivore insectivore

• Animal Foods
• birds
• mammals
• amphibians
• reptiles
• eggs
• insects
• terrestrial non-insect arthropods

Predation

Racers are eaten by birds , dogs , cats , and coyotes .

Ecosystem Roles

Coluber constrictor is a mid-level predator, eating many kinds of smaller animals, but in turn eaten by larger predators.

Economic Importance for Humans: Positive

Racers are beneficial to humans in that they destroy rodent and insect pests (Harding, 1997).

• Positive Impacts
• controls pest population

Economic Importance for Humans: Negative

Racers have no known neagtive impact on humans. If handled or harassed, they may bite, but will not deliberately confront a human.

• Negative Impacts
• injures humans
  • bites or stings

Conservation Status

This species is still abundant in some places. A few states (Maine and Louisiana) and the Canadian province of Ontario give it legal protection because it is rare there.

Pesticide residue poses a danger to insectivorous young racers. The dangers faced by adults include their habitat reduction because of agriculture and suburban/urban development along with direct killing of snakes by people (Harding, 1997).

Other Comments

The species name "constrictor" would lead one to think this is a constricting snake. This is not true. When the Swedish naturalist Linnaeus first described and named this species in 1758, he may have had it confused with the Black Rat Snake ( Elaphe obsoleta ), which is a true constrictor (Morris, 1944).

This is one of the largest snake species in Michigan (Harding 1997).

Additional Links

Encyclopedia of Life

BioKIDS Critter Catalog

Contributors

George Hammond (editor), Animal Diversity Web.

Angie Hastings (author), Michigan State University, James Harding (editor), Michigan State University.

References

Conant, R., J. Collins. 1998. Reptiles and Amphibians: Peterson Field Guides. 3rd Ed. . New York: Houghton Mifflin Company.

Ernst, C., R. Barbour. 1998. Snakes of Eastern North America . Virginia: George Mason University Press.

Greene, H. 1997. Snakes: The Evolution of Mystery in Nature . California: University of California Press.

Harding, J. 1997. Amphibians and Reptiles of the Great Lakes Region . Ann Arbor, MI: University of Michigan Press.

Morris, P. 1944. They Hop and Crawl . PA: The Jaques Cattell Press.