I have to assume you mean black, blue, and brown. The black racer is Coluber constrictor constrictor; the blue is C. c. foxii; and the brown is C. c. flaviventris, or possibly a brown variation of the blue racer. It is a matter of different subspecies, unless you're looking at variation in a ssps, like the blue racer is sometimes brownish in the southern or western parts of its range.

TC

>>Does anyone know what infuences the eastern racer snake changes to one of the three colors?