The Natural History and Captive Care of the Black (Eastern) Ratsnake, Elaphe (obsoleta) alleghaniensis

Overview
The black rat snake and the related corn snake, E. guttata, were among the first to become firmly established in North American herptoculture, and remain pet trade staples. At least 11 species of the genus Elaphe are found throughout North and Central America.

The taxonomy of this genus is confusing due to a wide variation in the appearance of individuals of the same species, and to the fact that different species inter-breed where their ranges overlap. The black ratsnake was formerly known as E. obsoleta, but that name is now assigned to the Western ratsnake. Recently, genetic evidence has shown that many North American ratsnakes should actually be classified within the genus Pituophis, along with the bull, gopher and pine snakes.

Physical Description
Although usually a uniform black in color, with an off-white underside, some individuals show traces of dark gray blotches and stripes. Juveniles differ markedly from adults, being pale gray and strongly patterned in dark gray or brown. Hobbyists have developed a number of unique color morphs, including albino individuals, and frequently hybridize this snake with related species. Black ratsnakes average 3 – 5 ½ feet in length, with the record holder being a giant of 8 ½ feet recorded from Westchester County, NY by noted herpetologist Raymond Ditmars.

Black ratsnakes living from North Carolina through the Florida Keys vary greatly in appearance from northern specimens, being various shades of yellow and orange in color. Formerly classified as distinct subspecies, known as the Everglades’s ratsnake and yellow ratsnake (both popular in the pet trade), they are now considered to be local color variations of the black ratsnake.

Range and Habitat
Black ratsnakes occupy much of Eastern North America – from SW New England and S Ontario to the Florida Keys and from SW Wisconsin to Oklahoma and N Louisiana. Happily for NYC-based “herpers” such as I, they are still to be found within NYC limits (parks in the Bronx and Staten Island), and in suburban Long Island and Westchester. Quite adaptable as regards habitat, they utilize forests, fields, rocky hillsides, swamps and overgrown suburban lots. It is one of many snake species drawn to farms, stone walls, trash dumps and abandoned buildings in search of mice and rats. In some habitats, black ratsnakes are highly arboreal and shelter in tree hollows.

Status in the Wild
Population levels appear stable in most areas, although the species is listed as of “Special Concern” in Minnesota and elsewhere. It adjusts well to some human presence and, if left alone, may become common on farms and near refuse disposal areas. Large scale captive breeding has removed collection pressures from wild populations.

Diet
Black ratsnakes are powerful constrictors. They tend, as adults, to focus on mammalian prey such as squirrels, chipmunks, rabbits, bats, voles, deer mice, rice rats, small opossums and similar creatures, but also take birds and their eggs. Young snakes include lizards, frogs and large insects (i.e. cicadas) in their diet.

A colleague of mine observed 6 foot-long (yellow-phase) black ratsnake attempting to constrict a white-tailed deer fawn on St. Catherine’s Island, Georgia. The fawn, which might have set a new “snake swallowing record” had it been overcome, eventually escaped.

Reproduction
Mating occurs from March to May, with 6-30 eggs being laid 27-28 days thereafter. Second clutches, laid in August, have been reported in captive situations but not in the wild. The eggs are secreted in cavities below fallen trees and rocks, or within rotting logs and stumps. The young, 11 – 13 ½ inches in length, hatch in 47-85 days.

Miscellaneous
The black ratsnake frequently shares hibernation dens with rattlesnakes, copperheads and other species. In some parts of the country it is known as the “pilot blacksnake” or “rattlesnake pilot”, in the mistaken belief that it guides rattlesnakes to their winter retreats.

Black Ratsnakes as Pets

General
With their moderate size and even temperaments, black ratsnakes make excellent pets. They are hardy enough for beginning hobbyists, and yet are so interesting that even well- experienced keepers often reserve a place for 1 or 2 in their collections.

Space and Other Physical requirements
Black ratsnakes do well in glass terrariums or aquariums which, ideally, should be a bit longer than the snake itself and as wide as possible. Be sure to secure the tank’s screen top with cage clips, as snakes are notorious escape artists. Cypress mulch or other substrates designed for use with snakes should cover the cage bottom. A reptile-safe disinfectant should be used to swab the cage floor after the snake defecates.

Rat snakes appreciate a shelter in which to hide and a bowl large enough for soaking. The water bowl should be filled to a level such that it will not overflow when the snake enters, as damp terrarium conditions may lead to respiratory and skin infections. If space permits, a stout branch for climbing and basking should be included.

American hobbyists favor a fairly “sterile” set up for rat snakes, but in Europe they are commonly kept in large, planted exhibits. Black ratsnakes take well to these, and, while management is a bit more complicated, the range of behaviors exhibited by snakes in such settings makes the undertaking well-worthwhile. I shall write more about keeping snakes in naturalistic exhibits in a future article.

Light, Heat, Humidity, etc.
Cage temperatures should range from 75 – 82 F, with a basking spot of 88 – 90 F. This species has no need for UVB light, but full spectrum lamps emitting UVA may be of some value. The cage should be kept dry at all times (see above).

Feeding
Black ratsnakes thrive on a diet of mice and rats. They take readily to dead prey and should not be offered live rodents due to the likelihood of injury to the snake. Adults should be fed every 7-10 days.

Captive Longevity
The captive longevity record for this species is just over 34 years.

Handling
Although black ratsnakes will, like most animals, bite in self-defense, they are, as a whole, mild-tempered. Most respond well to gentle handling, but individual animals vary greatly in this regard. Never startle a snake by picking it up suddenly, and do not handle snakes after you have touched food animals. Future articles will deal with the specifics of handling in detail.

Breeding
Breeding will be covered in depth in a future article. Except for snakes originating in the southern-most portions of the range, black ratsnakes breed most reliably when subjected to a winter cooling period. This species has been bred in captivity through multiple generations.

Miscellaneous
A number of European and Asian relatives, such as the Russian ratsnake, E. schrencki, may be kept as described for the black ratsnake. Other species referred to as “ratsnakes”, such as the arboreal red-tailed ratsnake, Gonyosoma oxycephala, have slightly different husbandry requirements. Please be sure to research potential pets carefully, as trade names can be misleading.

Additional Resourceshttp://people.wcsu.edu/pinout/herpetology/eobsoleta/index.html (detailed information on natural history)