Adult snakes commonly measure in total length, with a few exceeding. The longest recorded total length to date is. Adults are shiny black dorsally, with a cream or white chin and throat. The belly has an irregular black and whitecheckerboard pattern, becoming uniformly slate gray towards the tail. Juveniles have dark dorsal blotches on a grayish ground color. The ventral pattern in juveniles is the same as in adults. The eyes are round with a black pupil, and particularly in juveniles but not always present in adults, a distinct white margin. The dorsal scales are weakly keeled, and are arranged in 23 to 27 rows at midbody. Males and females have the same coloration. Males have proportionally longer tails compared to females.
Habitat
The eastern rat snake occurs in a variety of habitats. These include farmlands, hardwood forests, forested wetlands, thickets and fields adjacent to forests, isolated urban woodlots and backyards that support populations of prey species. Eastern rat snakes do especially well in early successional and edge habitats. An arboreal species, the snakes can get into human residences, where they may live in attics undetected. At the northern limits of their range, distribution appears to be restricted by the availability of suitable hibernating sites. In these climates, the snakes require southern exposures to receive maximal thermal benefit from the winter sun and to provide basking areas in early spring and late fall.
Behavior and ecology
The eastern rat snake is primarily active at night during the summer, and diurnal in the spring and fall. It is a terrestrial burrower and an excellent climber, and it may enter water. It is found under rocks and boards, and in trees under bark and within knot holes and palm fronds. The snake is a constrictor, and adults eat mainly endotherms while young eat mainly ectotherms. The diet includes rodents, lizards, frogs, and birds and their eggs. The snakes can also eat young chickens and chicks, hence the common name chicken snake. Rat snakes are most vulnerable to predators as juveniles. Predators of P. alleghaniensis include hawks, great horned owls, foxes, raccoons, and domestic cats. Adult eastern rat snakes have few known predators other than humans. When frightened, a rat snake will freeze. If harassed, it will produce a foul-smelling musk to deter predators. If provoked further, it may coil, shake its tail, and snap at its attacker. The snakes hibernate during the winter underground or in deep crevices. They may congregate in the same dens with other species of snakes, such as copperheads, eastern racers and timber rattlesnakes. In Northern climes, the snakes are active from late April to October and mate in May or June. It is active earlier in the South. Rat snakes reach sexual maturity in their fourth year. The snakes start to breed in May and June, earlier in the South. Males approach females to initiate breeding and may combat other males before breeding. About five weeks after mating, the female lays 5 to 27 eggs in hollow standing and fallen trees, compost and mulch heaps, sawdust piles, and decomposing logs. Incubation is about two months, and eggs hatch from July through September. Hatchlings are usually just over a foot long at birth, with the distinct gray and black pattern characteristic of juveniles.
Taxonomy
Pantherophis alleghaniensis has sometimes been considered a subspecies of Pantherophis obsoletus, to which it is closely related. This species has often been placed in the genusElaphe, but recent phylogenetic analyses have resulted in its transfer to Pantherophis.
