Coluber constrictor

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.

Biogeographic Regions: nearctic (Native )

This species occurs through most of the United States, and ranges into southern Canada and northern and eastern Mexico, discontinuously southwards to Guatemala and Belize. It 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). Elevational range extends from sea level to about 2,550 m (8,300 feet). A record for Durango, Mexico, evidently is erroneous (Webb 2001).

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 (Native )

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) 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).

Continent: Middle-America North-America
Distribution: S Canada (incl. Saskatchewan) USA (Washington, Oregon, California, Illinois, New Mexico, Texas, Oklahoma, Kansas, Nebraska, Minnesota, Colorado, Wyoming, Montana, South Dakota, Idaho, Utah, Iowa, Missouri, Arkansas, Louisiana, Mississippi, Alabama, Georgia, Florida, South Carolina, North Carolina, Virginia, West Virginia, Kentucky, Indiana, Illinois, Wisconsin, Ohio, Maryland, Pennsylvania, New Jersey, New York, Rhode Island, Connecticut, Massachusetts, S New Hampshire, S Vermont, S Maine; Tennessee [latrunculus: HR 31: 54]) E/SE Mexico (Yucatan, Durango), Belize, N Guatemala  constrictor: S Maine to NE Alabama.  anthicus: S Arkansas, Louisiana, E texas.  etheridgei: WC Louisiana, adjacent Texas.  flaviventris: Montana, W North Dakota, east to Iowa and south to Texas, SW Louisiana; Arkansas, Colorado, Kansas, Missouri, Michigan, Wisconsin, Oklahoma; isolated populations in New Mexico and Texas.  foxii: S Ontario, NW Ohio to E Iowa and SE Minnesota; Wisconsin; an isolated population in Menominee Co., Michigan (intergrades with flaviventris).  helvigularis: Lower Chipola and Apalachicola R. valleys in Florida panhandle and adjacent Georgia.  latrunculus: SE Louisiana north along the east side of the Mississippi to N Missouri.  oaxacae: S Texas and Tamaulipas to C Veracruz; isolated records in Nuevo León, Coahuila, Durango, Colima, Oaxaca, Chiapas, and Guatemala.
Type locality: “Mexico”. Seems to intergrade with flaviventris in New Mexico and Texas. Holotype: MNHN.  paludicola: Everlglades, SE Florida, upper Florida Keys, E Florida. Holotype: USNM  priapus: SE states and north and west in Mississippi valley to S Indiana and SE Oklahoma, Lower Florida Keys.  
Type locality: “Canada”

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.

Range length: 191 (high) cm.

Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry

Sexual Dimorphism: sexes shaped differently

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).

Range length: 191 (high) cm.

Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry

Sexual Dimorphism: sexes shaped differently

Length: 196 cm

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.

Habitat Regions: temperate

Terrestrial Biomes: savanna or grassland ; chaparral ; forest ; scrub forest ; mountains

Wetlands: marsh ; swamp ; bog

Other Habitat Features: agricultural

Habitat and Ecology

Systems

• Terrestrial

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

Terrestrial Biomes: savanna or grassland ; chaparral ; forest ; scrub forest ; mountains

Wetlands: marsh ; swamp ; bog

Other Habitat Features: agricultural

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).

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

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).

Racers are carnivores. They have very broad diets. Juvenile racers eat mainly Insecta, Araneae, small Anura, small reptiles (including Sauria and Serpentes and their eggs) and young Rodentia and Soricidae. As racers grow, they take larger prey as well, including nestling Aves and their eggs, other Mammalia as large as Sciuridae and small Sylvilagus, small Testudines and larger snakes.

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

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).

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

Primary Diet: carnivore (Eats terrestrial vertebrates, Insectivore )

Comments: Diet typically includes small mammals, birds, reptiles, amphibians, and large insects.

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

Racers are eaten by Aves, Canis lupus familiaris, Felis silvestris, and Canis latrans.

Known Predators:

• domestic dogs (Canis_lupus_familiaris)
• domestic cats (Felis_silvestris)
• coyotes (Canis_latrans)
• birds (Aves)

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

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

Known Predators:

• domestic dogs (Canis lupus familiaris)
• domestic cats (Felis silvestris)
• coyotes (Canis latrans)
• birds (Aves)

Coluber constrictor preys on:
Diadophis punctatus
Dendroica petechia

This list may not be complete but is based on published studies.

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: > 300

Comments: This species is represented by a very large number of occurrences or subpopulations (at least several hundred).

>1,000,000 individuals

Comments: Total adult population size is unknown but probably exceeds 1,000,000. This snake is common in most of its very large range in the United States but appears to be rare at the southern extent of the range in southern Mexico, Guatemala, and Belize (Lee 2000).

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.

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

Perception Channels: visual ; tactile ; chemical

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

Perception Channels: visual ; tactile ; chemical

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).

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

Range lifespan
Status: wild: 10 (high) years.

Average lifespan
Status: captivity: 10 years.

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

Range lifespan
Status: wild: 10 (high) years.

Average lifespan
Status: captivity: 10 years.

Maximum longevity: 10 years

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.

Breeding interval: 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.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous

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).

Breeding interval: 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.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous

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.

The following is a representative barcode sequence, the centroid of all available sequences for this species.

There are 2 barcode sequences available from BOLD and GenBank.  Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.  See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

Download FASTA File

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 2
Specimens with Barcodes: 8
Species With Barcodes: 1

Canada

Rounded National Status Rank: N3 - Vulnerable

United States

Rounded National Status Rank: N5 - Secure

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.

IUCN Red List of Threatened Species: least concern

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

Year Assessed

Assessor/s

Reviewer/s

Justification

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).

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

Rounded Global Status Rank: G5 - Secure

Intrinsic Vulnerability: Moderately vulnerable

Population

Population Trend

Global Short Term Trend: Relatively stable (=10% change)

Comments: Extent of occurrence, area of occupancy, number of subpopulations, and population size are very large and probably relatively stable.

Global Long Term Trend: Increase of 10-25% to decline of 30%

Degree of Threat: Low

Comments: No major threats have been identified. Historically, some populations undoubtedly experienced significant declines, particularly in major agricultural regions of intensive cultivation. Remaining populations are extensive and not threatened in most areas.

Major Threats

Conservation Actions

Global Protection: Very many (>40) occurrences appropriately protected and managed

Comments: Many occurrences are in national parks and other protected areas.

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)

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

Positive Impacts: controls pest population

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)

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

Positive Impacts: controls pest population