Southern Black Racer (Coluber constrictor)

Description:    The southern black racer is a slender, fast-moving colubrid typically reaching 4.5 ft (1.3 m) in total length, with some individuals exceeding 5.5 ft (1.67 m). Adults are glossy black, with a white-to-gray chin and throat and a uniformly dark body. Juveniles are patterned with reddish-brown spots with a gray or brown body, resembling young rat snakes, and gradually darken to solid black with age. Adult racers can be distinguished from black rat snakes by their smooth scales, lack of spotting, more slender body and head, and their lack of black vertical lines on their lips.

Range and Habitat:    The southern black racer is widespread across the southeastern United States, ranging from North Carolina through Florida and west into eastern Texas. In Georgia and South Carolina, they are found throughout the Piedmont, Coastal Plain, Blue Ridge, and Appalachian plateau regions. They inhabit a wide variety of ecosystems, including pine flatwoods, hardwood forests, scrub, grasslands, old fields, wetlands, and suburban edges. Racers are habitat generalists, often favoring ecotones and open-canopy areas for thermoregulation.

Habits:    Racers are highly diurnal and among the most active snakes in the Southeast. They are rapid foragers that actively hunt for prey rather than sit and ambush it. They have excellent vision and speed that make them proficient at pursuing prey and evading predators. When threatened, racers often flee quickly, but if cornered, they may vibrate their tails, strike repeatedly, and excrete a foul musk. Seasonal surface activity peaks differ between sympatric rat snakes and racers: racers exhibit higher summer activity, whereas rat snakes are more frequently encountered in spring and fall.

Southern black racers are opportunistic generalist predators. Studies reveal a broad diet including lizards, frogs, snakes, rodents, insects, and small birds. In South Carolina populations, lizards and snakes constitute over 85% of stomach contents by volume, with rodents and insects comprising smaller proportions. Hatchlings exhibit strong chemosensory responses to lizard prey, such as anoles.

Breeding occurs in spring, with females laying clutches of 4-30 eggs in decaying logs, leaf litter, or sandy soils. Incubation averages 8-10 weeks, and hatchlings emerge in late summer at 8-12 in (20-30 cm) total length.

Southern black racers are mid-level predators and exert strong predation pressure on small vertebrate populations. They themselves fall prey to raptors, mammals, and larger snakes. Most predation records indicate that the most common predators are kingsnakes, coachwhips, and hawks.

Conservation Status:    The southern black racer is common and widespread and is currently listed as a species of Least Concern. Because of their diurnal surface activity and tendency to cross roads, racers are highly susceptible to road mortality. In addition, habitat loss and fragmentation, human persecution, and feral cats contribute to local declines. However, their adaptability to disturbed environments and generalist diets supports stable populations. Although they are not protected across most of their range, they are protected in the states of Georgia and South Carolina.

Pertinent References

• DeGregorio, B.A., et al. 2016. Do seasonal patterns of rat snake (Pantherophis obsoletus) and black racer (Coluber constrictor) road mortality correspond to seasonal surface activity? Ecology and Evolution 6: 3951-3961.
• Cooper, W.E. Jr., G.M. Burghardt, & W.S. Brown. 2000. Behavioural responses by hatchling racers (Coluber constrictor) from two geographically distinct populations to chemical stimuli from potential prey and predators. Amphibia-Reptilia 21: 103-115
• Ernst, C.H. & E.M. Ernst. 2003. Snakes of the United States and Canada. Smithsonian Institution Press, Washington, D.C.
• Additional natural history observations in: Herpetological Review (2021). Predation records involving racers