The black ratsnake, Elaphe alleganiensis, found throughout much of the eastern half of North America (even in NYC, on occasion, and its suburbs), is a pet trade staple. Hobbyists have developed a number of unique color morphs, including albino individuals, and frequently hybridize this snake with related species. Since so much is known of its natural history and captive care, I thought I would note here some recent changes regarding its relationships to similar snakes.
The taxonomy of the genus Elaphe is confusing due to a wide variation in the appearance of individuals of the same species, and to the fact that the various species and subspecies inter-breed where their ranges overlap (one reason for the ease in creating different color phases in captivity). Most snake enthusiasts grew up knowing the black ratsnake as Elaphe obsoleta, but that name is a now assigned to the Western ratsnake, with the black ratsnake being re-named as E. alleganiensis. At least 11 species of snake of the genus Elaphe are found throughout North America.
To add to the confusion, black ratsnakes living from North Carolina through the Florida Keys vary greatly in appearance from northern populations, being various shades of yellow and orange in color instead of black. Formerly classified as distinct subspecies, known as Everglades ratsnakes and yellow ratsnakes – both also quite popular in the pet trade – they are now considered to be merely local color variations of the black ratsnake.
The black ratsnake frequently shares hibernation dens with rattlesnakes and copperheads. 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. The largest individual on record measured 8 ½ feet long.
The latest information concerning changes in reptile classification and taxonomy is available at the website of the American Museum of Natural History’s herpetology department: