Black Rat Snake
It's the most widely distributed rat snake with a range extending from New England south through Georgia and west across the northern parts of Mississippi, Louisiana, and Alabama, and north through Oklahoma to southern Wisconsin. Isolated populations can be found both in northern New York and southern Canada.
There aren't any subspecies currently recognized by scientists (see species/taxonomy below). The black rat snake is a medium-sized snake with an average length ranging from 40 to 70 inches (1,0 to 1,77 m), and as its name suggests, is completely black except for the white chin and belly.
The species is also known by other common names like the Texas rat snake or pilot black snake. In some areas, they are called simply “black snakes” and are often confused with racers like the southern black racer, but unlike them, the black rat snake has keeled scales. Just like their close relatives the eastern rat snake they are sometimes called chicken snake.
Black rat snakes usually inhabit woodlands but can be often found in a variety of other habitats like river floodplains, swamp borders, rocky hillsides, mountain ledges, farmlands or open fields.
They have also adapted to live in more developed areas, residing in houses, yards, and farm buildings where they hunt down mice. These snakes are very skillful climbers and will climb high up in trees to find prey, but also climb rafters in barns and other buildings.
Species / Taxonomy
Old and New World rat snakes were commonly classified in the same genus, Elaphe, up until early 2000's.
Now rat snakes found in North America are considered more closely related to the king snakes like the California kingsnake than to the Old World rat snake species.
But since then the black rat snake scientific classification has undergone several changes in recent years. The species was moved to an entirely separate genus with 3 new species also proposed.
These snakes were previously placed in the genus Elaphe, as Elaphe obsoleta, but phylogenetic studies moved them to the genus Pantherophis as the western rat snake (Pantherophis obsoletus). In 2008, the genus Scotophis was resurrected for the 3 species but subsequent studies dismissed these changes.
The other species with these changes were the central ratsnake (Pantherophis spiloides) and the eastern ratsnake (Pantherophis alleghaniensis), even though the 3 species are morphologically identical. With more recent studies indicating that the central ratsnake and the eastern ratsnake interbreed freely in Ontario.
Diet / Feeding
Like boas and pythons the black rat snake is a powerful constrictor, once it catches it's prey, it will wrap the body around it and squeeze until the unfortunate animal dies.
Black rat snakes eat a variety of animals including lizards, frogs, chipmunks, squirrels, small rabbits, mice, rats, bats, voles, shrews, other small mammals and even other snakes.
They also eat birds and their eggs. Like other snakes, the digestion is a very slow process and sometimes it takes several days for a prey to be fully digested. While young snakes may feed on a weekly basis, older snakes will only feed 1 or 2 times a month.
Like most snake species the black rat snake is an egg layer or oviparous. The black rat snake usually mates only once a year, but if conditions permit, females will sometimes produce 2 clutches of eggs in a year. The species reaches sexual maturity at 3 or 4 years of age.
The mating season occurs in late May and early June, shortly after the snakes have emerged from hibernation in March or May. In preparation for mating and to communicate both males and females release pheromones.The mating act itself may last from a few minutes to a few hours.
Males will fight each other for the right to mate with the receptive females. The males will commonly mate with several females, that stay pregnant for a period of about 5 weeks.
The female black rat snake lays a clutch of 3 up to 30 eggs, in abandoned burrows, piles of dead leaves, rotten logs or under rocks. These will hatch in late August to early October around 65 to 70 days later.
The eggs measure roughly 2 inches in length, and when the young snakes hatch they are about 1foot (30 cm) long and are a pale gray with black or dark brown blotches along the back and sides. As they grow their color becomes darker until it becomes black.
Conservation / Threats
The black rat snake is one of the most common snake species found in Central and Eastern United States, and it's not listed as rare, threatened or endangered on a federal level.
The species is listed as Least Concern by IUCN because of its wide distribution, some tolerance to habitat modification and presumed large population numbers.
But still, these non-venomous snakes are often victims of roadkill and human persecution when mistaken with other venomous snake species like copperheads.
They are listed as special concern species in the state of Michigan as their habitat is being reduced due to land development.
Did You Know?
Because of the "Mojave toxin" the Mojave rattlesnake venom is regarded as the most toxic of any rattlesnake.