The gray rat snake (Elaphe obsoleta spiloides), also known as the Central ratsnake (Pantherophis spiloides), is a member of the genus Elaphe in the subfamily Colubrinae. Within the genus Elaphe, which includes rat snakes, corn snakes, and fox snakes, the gray rat snake is one of five subspecies, or races, of the black rat snake (E. obsoleta). The subspecies of Elaphe obsoleta include: the nominate black rat snake (E. o. obsoleta), gray rat snake (E. o. spiloides), yellow rat snake (E. o. quadrivittata), Everglades rat snake (E. o. rossalleni), and Texas rat snake (E. o. lindheimeri). However, many authorities do not currently recognize any of these subspecies.
A medium to large serpent, gray rat snakes (silver racer) typically reach an adult size of 39" to 72" (3.25–6 feet/99 cm-183 cm), however, the record is 84.5"(7.041 ft/2.15m). Unlike other Elaphe obsoleta whose conspicuous juvenile pattern fades into adulthood, gray rat snakes do not undergo drastic ontogenetic changes in color, or markings. These snakes retain the juvenile pattern of dark elongate dorsal blotches separated by four, or more, pale gray body scales, a light gray crown with dark striping that forms an anteriorly facing spearpoint, and a solid band which covers the eyes and extends rearward to the posterior upper labial scales. The venter is usually off-white or pale gray with darker irregular blotches, and a double row of black spots behind the divided anal plate of the vent. The dorsal scale rows around midbody are usually weakly keeled. Because the gray rat snake shares its range with other members of its species, intergrades of black/gray and yellow/gray rat snakes are not uncommon.
Native to North America, the Gray Ratsnake is commonly found in the forests of eastern and central United States. It occurs relatively continuously throughout the major part of the eastern half of the United States, along the western edge of the Appalachian Mountains, from southwestern New England to the Gulf of Mexico, westward to the Mississippi River, and northward from northern Louisiana to southwestern Wisconsin.
In Canada, this species is known to occur in two disjunct regions of Southern Ontario: the Carolinian forest region along the north shore of Lake Erie in the southwest, and the Great Lakes/St. Lawrence region in the southeast.
An agile climber, gray rat snakes are at home from the ground to the tree tops in many types of hardwood forest and cypress stands, along tree-lined streams and fields, and even barns and sheds in close proximity to people. Within its range, almost any environment rich in rodents, and vertical escape options, proves a suitable habitat for the gray rat snake. As scent-hunters these powerful constrictors feed primarily on rodents, birds, and their eggs as adults, while neonates and juveniles prefer a diet of frogs and lizards. When startled, this species, like other rat snakes, stops and remains motionless with its body held in a series of wave-like kinks. The gray rat snake will defend itself by raising its head and bluffing a strike. If handled, these snakes will musk a victim by releasing the foul-smelling contents of their cloaca, and will bite if necessary. However, the gray rat snake is less likely to bite than other members of its species, and wounds from a bite rarely require more than a bandage. Breeding takes place from April to July. Females deposit 5 to 27 eggs around mid-summer, and the 10" to 12" (25–30 cm) hatchlings usually emerge in September.
While a taxonomic suggestion has been made to change the genus Elaphe to Pantherophis, and this suggestion has been taken up by the web community at large, most herpetologists do not accept the suggestion and Herpetological Review 2003 34(3) rejected the taxonomic change. One argument against the change is that the Russian study, which suggested it, was based on mitochondrial DNA evidence, not nuclear DNA; and thus no relevance to the reproductive and nuclear genetic relatedness of the genera can be inferred from the data.
The gray rat snake is considered common and is not listed as a protected species by any states within its range. However, in the state of Georgia, all indigenous, nonvenomous snakes are illegal to kill or capture, and are considered to be in the custody of the Georgia Department of Natural Resources.