Coluber

Coluber is a genus of nonvenomous snakes, family Colubridae, historically containing many species now split into several other genera; as currently recognized it contains a single species, the eastern racer, Coluber constrictor, with eleven recognized subspecies. The eastern racer ranges throughout much of the United States on both sides of the Rocky Mountains, and extends north into Canada and south into Mexico, Guatemala and Belize. Adults typically measure 50 to 152 centimeters, are fast moving, highly active daytime hunters with excellent vision, and most subspecies are solid colored, black, brown, tan, blue or green, with lighter undersides, while juveniles show a middorsal row of dark blotches on a lighter ground color that fades with age. The snakes are known for a head-raising, surveying behavior sometimes called periscoping.