Grownup racers are usually uniformly darkish in coloration dorsally, with a lighter-coloured venter, although juveniles have a blotchy checkered sample (Fitch 1963). The precise shade varies throughout the species’ vary and a lot of subspecies have been recognised such because the blue racer Coluber constrictor foxii and the northern black racer C. c. constrictor. Basically, people are darker in direction of the east and north, and lighter in direction of the west and south. Wilson (1978) listed eleven subspecies of C. constrictor whereas a phylogeographic research of the species by Burbrink et al. (2008) recognized six main lineages. In addition to coloration, members of those lineages might differ in elements similar to behaviour or genital morphology, and future research might even see them elevated to the rank of separate species.
The pure historical past of Coluber constrictor was reviewed intimately by Fitch (1963). Because the vernacular title of ‘racer’ suggests, Coluber constrictor is a quick mover. Its weight loss plan comprises a mix of small vertebrates, similar to frogs, lizards and small mammals, and huge invertebrates similar to grasshoppers, crickets and caterpillars. Foraging people typically maintain the entrance finish of the physique raised above the bottom. Regardless of their species title, racers don’t kill their prey by constriction. As an alternative, they principally seize prey by darting ahead rapidly and grabbing it, typically swallowing prey reside. Fitch recorded one event when he noticed a racer within the means of subduing a big skink. Whereas the snake was swallowing its prey, Fitch tried to seize it. The racer disgorged the skink, and each snake and lizard escaped the scene. Eating regimen might range with measurement, with smaller people taking the next proportion of invertebrates, but in addition varies with vary. Populations within the west might primarily feed on bugs whereas others might virtually solely take vertebrates. The northern black racer of the northeastern United States is probably the most inclined of the subspecies to feed on different snakes. Cannibalism isn’t unknown; at the least one writer recorded observing it amongst broods raised in captivity. In a single case, two younger racers latched onto a single lizard. Considered one of them efficiently downed the lizard, after which additionally continued on to devour the snake connected to the opposite finish, regardless of the swallowed snake being almost as massive as its swallower.
Throughout winter, racers hibernate in crevices and hollows amongst rocks. Most well-liked hibernation areas are sometimes on the prime of hills, away from their regular looking websites. Mating and egg-laying happens shortly after emergence with the height of egg-laying being in early June (Rosen 1991). Racers, notably the big northern black, might change into extra aggressive throughout this era. Eggs are buried shallowly, in free soil or underneath litter, although females might make the most of deserted mammal burrows to offer a safer location. As with different snakes, laying appears to be a matter of pump and dump; I did not come throughout any references to females defending clutches. After hatching, males take a couple of yr to succeed in sexual maturity whereas the bigger females take about two years. Fitch (1963) reviews encountering the identical people over the course of a number of years (recognisable by their bearing the scars of prior assortment of scale samples). Nonetheless, nearly all of racer hatchlings don’t survive their first summer season. Few get the chance to hunt out shelter for his or her winter’s sleep.
Burbrink, F. T., F. Fontanella, R. A. Pyron, T. J. Guiher & C. Jimenez. 2008. Phylogeography throughout a continent: the evolutionary and demographic historical past of the North American racer (Serpentes: Colubridae: Coluber constrictor). Molecular Phylogenetics and Evolution 47: 274–288.
Fitch, H. S. 1963. Pure historical past of the racer Coluber constrictor. College of Kansas Publications, Museum of Pure Historical past 15 (8): 351–468.
Myers, E. A., J. L. Burgoon, J. M. Ray, J. E. Martínez-Gómez, N. Matías-Ferrer, D. G. Mulcahy & F. T. Burbrink. 2017. Coalescent species tree inference of Coluber and Masticophis. Copeia 105 (4): 640–648.
Wilson, L. D. 1978. Coluber constrictor Linnaeus. Catalogue of American Amphibians and Reptiles 218: 1–4.