Racer
Coluber constrictor

Statewide.  A common but secretive snake, the racer is adept at climbing trees in pursuit of prey, which may include nearly anything from birds and rodents to lizards and other snakes.  Racers are extremely quick, one of the fastest snakes in the world.  Although nonvenomous, racers are also quick to bite when startled and/or disturbed, such as when being handled, and the bites can result in painful lacerations. 

Biologists can sometimes be classified as splitters (those who subspeciate everything) and lumpers (those who don't believe in subspecies).  Whatever your position, the many variable races or morphs of racers (and other species) vary greatly throughout its distribution.  Oklahoma is home to two subspecies or morphs of racers.  The eastern yellowbelly, C. c. flaviventris (pictured), and the southern black, C. c. priapus.