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black racer

Coluber constrictor

What do they look like?

Coluber constrictor is a long, slender snake, which can reach lengths of 6 feet (191 cm). They range in color from blue in the north to black in the south and yellow and gray in the western U.S. The blue and black racers have no skin patterns, but some other racers have spots or blotches. Racers in Michigan are a dark-blue color and have white chins.

Young racers have a gray body covered with brown or red bands. (Conant and Collins, 1998; Harding, 1997)

  • Sexual Dimorphism
  • sexes shaped differently
  • Range length
    191 (high) cm
    75.20 (high) in

Where do they live?

Racers are found from southern Canada to Guatemala and almost everywhere in between. These snakes can be found in every state of the U.S, including Michigan's southern lower peninsula. (Conant and Collins, 1998; Ernst and Barbour, 1998)

What kind of habitat do they need?

Racers live in dry, sunny areas such as old farm fields, grass meadows, thin forests, and swamps. During the coldest winter months, racers hibernate in underground shelters. (Greene, 1997; Harding, 1997)

  • These animals are found in the following types of habitat
  • temperate

How do they reproduce?

Racers mate in the spring and lay 3-32 oval-shaped eggs in early summer underneath tree stumps or in animal burrows. Sometimes, the eggs are found grouped with the eggs of other snake species. (Conant and Collins, 1998; Greene, 1997)

  • How often does reproduction occur?
    Mating takes place in the spring, from late April until early June.
  • Breeding season
    June to early July
  • Range number of offspring
    3 to 32
  • Range age at sexual or reproductive maturity (female)
    2 to 3 years
  • Range age at sexual or reproductive maturity (male)
    1 to 2 years

How long do they live?

In the wild, racers have been known to live over 10 years. (Ernst and Barbour, 1998)

  • Range lifespan
    Status: wild
    10 (high) years
  • Average lifespan
    Status: captivity
    10 years

How do they behave?

Racers are fast snakes, but they still can only crawl at about 4 miles per hour (6.5 km/hr), about the speed of a human walking fast. If threatened, a racer will quickly crawl into brush or low branches of a tree to escape. If cornered, Coluber constrictor will coil and strike while shaking its tail nervously. The racer is not venomous, but the painful bite and sharp teeth may cause bleeding. The young racers' color patterns probably mean they use camouflage for escape from predators. These snakes are diurnal, they are mainly active during the day. (Conant and Collins, 1998; Harding, 1997)

How do they communicate with each other?

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

What do they eat?

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. (Conant and Collins, 1998; Greene, 1997)

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

What eats them and how do they avoid being eaten?

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

What roles do they have in the ecosystem?

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

Do they cause problems?

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

  • Ways that these animals might be a problem for humans
  • injures humans
    • bites or stings

How do they interact with us?

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

  • Ways that people benefit from these animals:
  • controls pest population

Are they endangered?

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

Chemical pesticides harm young racers. All racers have problems when their habitat is destroyed to build farms, houses, and other buildings. Then they have few places to hide, little to eat, and people who find them often kill them, even though they are harmless. (Harding, 1997)

Some more information...

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 (Pantherophis obsoletus), which is a true constrictor (Morris, 1944).

This is one of the largest snake species in Michigan (Harding 1997). (Harding, 1997; Morris, 1944)


George Hammond (editor), Animal Diversity Web.

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



living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map


living in landscapes dominated by human agriculture.


a wetland area rich in accumulated plant material and with acidic soils surrounding a body of open water. Bogs have a flora dominated by sedges, heaths, and sphagnum.


an animal that mainly eats meat


mid-altitude coastal areas with mild, rainy winters and long, dry summers. Dominant plant types are dense, evergreen shrubs.


uses smells or other chemicals to communicate

  1. active during the day, 2. lasting for one day.

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.


animals that have little or no ability to regulate their body temperature, body temperatures fluctuate with the temperature of their environment, often referred to as 'cold-blooded'.


the state that some animals enter during winter in which bodily functions slow down, reducing their energy requirements so that they can live through a season with little food.


An animal that eats mainly insects or spiders.


offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).


marshes are wetland areas often dominated by grasses and reeds.


This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.


reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season


remains in the same area


reproduction that includes combining the genetic contribution of two individuals, a male and a female


lives alone


a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.


uses touch to communicate


that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

tropical savanna and grassland

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

uses sight to communicate


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.

University of Michigan Museum of ZoologyNational Science Foundation

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Hastings, A. 2002. "Coluber constrictor" (On-line), Animal Diversity Web. Accessed April 17, 2014 at

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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