[13] The longest recorded total length to date for an eastern rat snake is 228 cm (7 ft 6 in).

At the northern limits of its range, distribution appears to be restricted by the availability of suitable hibernating sites.

In these climates, it requires southern exposures to receive maximal thermal benefit from the winter sun and to provide basking areas in early spring and late fall.

[12][14] In one study tracking habitat conditions, eastern rat snakes were found to exhibit site fidelity; returning to the same location for 12% of observations.

[22] The three U.S populations located more northerly (Illinois at 378N, Kansas at 388, Maryland at 398) hibernate, with very rare appearances before April and after October.

[23] There are consequences of thermal constraints regarding ecological parameters such as causes of variation of seasonal mortality, population demography, limits to geographic distribution, and the expression or evolution of traits such as habitat selection, reproductive allocation, and mechanisms of physiological hibernation remain complex and incompletely understood.

[23] The eastern rat snake is primarily active at night during the summer, and diurnal in the spring and fall.

They may congregate in the same dens with other species of snakes, such as copperheads (Agkistrodon contortrix), eastern racers (Coluber constrictor) and timber rattlesnakes (Crotalus horridus).

[28] Eastern rat snakes are oviparous, and gaining nutrients for eggs is facilitated by the female maintaining her body temperature.

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.

Hatchlings are usually just over a foot long at birth, with the distinct gray and black pattern characteristic of juveniles.