Rat snakes are medium to large constrictors found through a great portion of the Northern Hemisphere. They feed primarily on rodents and birds. With some species exceeding 3 m (10 ft) in total length, they can occupy top levels of some food chains. Many species make attractive and docile pets and one, the corn snake, is one of the most popular reptile pets in the world. Other species can be very skittish and sometimes aggressive, but bites are rarely serious. Like nearly all colubrids, rat snakes pose no threat to humans. Rat snakes were long thought to be completely nonvenomous, but recent studies have shown that some Old World species do possess small amounts of venom (so small as to be negligible to humans).
Previously, most rat snakes were assigned to the genus Elaphe, but many have been since renamed following mitochondrial DNA analysis performed in 2002. For the purpose of this article, names will be harmonized with the TIGR Database[clarification needed].
Nota bene: In the above species lists, an authority's name in parentheses indicates that the species was originally described in a different genus. An authority's name not in parentheses indicates that the species is still assigned to the original genus in which it was described.
In recent years, some taxonomic controversy has occurred over the genus of North American rat snakes. Based on mitochondrial DNA, Utiger et al. (2002) showed that North American rat snakes of the genus Elaphe, along with closely related genera such as Pituophis and Lampropeltis, form a monophyletic group separate from Old World members of the genus. They therefore suggested the resurrection of the available name Pantherophis Fitzinger for all North American taxa (north of Mexico). Crother et al. (2008) accepted the taxonomic change to Pantherophis.
Rat snakes are commonly kept as pets by reptile enthusiasts. The corn snake, one of the most popular pet reptiles, belongs to the rat snake family. New World species are generally thought to be more docile in captivity as opposed to Old World rat snakes, of which the opposite is assumed.
^Crother BI, et al. (2008) Scientific and Standard English Names of Amphibians and Reptiles of North America North of Mexico: 6th edition. Herp. Rev. 37, pp. 58–59. or see pp. 64 ff in the 7th edition.