Western Ratsnake

Pantherophis obsoletus, also known commonly as the western rat snake, black rat snake (not to be confused with Pantherophis alleghaniensis), pilot black snake, or simply black snake, is a nonvenomous species of snake in the family Colubridae. The species is native to central North America west of the Mississippi River. No subspecies are recognized as being valid. Its color variations include the Texas rat snake. Along with other snakes of the eastern United States, like the eastern indigo snake (Drymarchon couperi) and the eastern racer (Coluber constrictor), it is called "black snake".

Geographic range

Pantherophis obsoletus is found west of the Mississippi River, from eastern and southern Iowa southward through Missouri and Arkansas to western Louisiana, westward to eastern Texas, northward through Oklahoma and eastern Kansas to southeastern Nebraska.

Aside from the usual variety that is black or has patches of black on a lighter background, color variations include the Texas rat snake, which is a brown-to-black variant, often with tinges of orange or red, that can be found in southern Oklahoma, Texas, and Louisiana.

Habitat

Rat snakes of the genus Pantherophis are primarily diurnally active and live in a variety of habitats; some overlap each other. They have adapted to a variety of habitats, including bayou, prairie, and rock outcrops, but they seem to have a particular preference for wooded areas, especially oak trees. They can also adjust their waking schedules in different habitats and exhibit facultative nocturnal behaviors. These rat snakes are excellent climbers and spend a significant amount of their time in trees. The black rat snake is also a competent swimmer.

During winter, they hibernate in shared dens, often with copperheads and timber rattlesnakes. When found in homes, they are often in groups. This association gave rise to one of its common names, pilot black snake, and the superstition that this nonvenomous species led the venomous ones to the den.

Description

Western rat snakes typically range 106.7 ‒183 cm. (42 ‒ 72 in.) in total length, with a record individual of 218.4 cm. (86 in.).

Juveniles are strongly patterned with brown blotches on a gray background (like miniature fox snakes: P. gloydi, P. ramspotti, and P. vulpinus). Darkening occurs rapidly as they grow. Adults are glossy black above with white lips, chin, and throat. Sometimes, traces of the "obsolete" juvenile pattern are still discernible in the skin between the scales, especially when stretched after a heavy meal.

Common names

Other common names for Pantherophis obsoletus include gray rat snake, black chicken snake, black coluber, chicken snake, mountain black snake, mountain pilot snake, pilot, rat snake, rusty black snake, scaly black snake, cow snake, sleepy John, and white-throated racer.

Behavior