Western Ratsnake

Pantherophis obsoletus

western_ratsnake_in_grass_1-2-15.jpg

Photo of a western ratsnake curled up in grasses under a fence.
Western ratsnakes take shelter in brushpiles, hollow trees, farm buildings, and old houses where mice are plenty.
Jim Rathert
Other Common Name
Black Snake, Black Rat Snake, Black Ratsnake, Texas Ratsnake
Family

Colubridae (nonvenomous snakes) in the order Squamata (lizards and snakes)

Description

Often called the "black snake," the western ratsnake is one of our state's largest and most familiar snakes. Generally shiny black, but some individuals show dark brown blotches. The skin between the scales along the sides may be red. The upper lip, chin, and lower part of the neck are usually white. The belly is white, mottled with gray, or it may be checkered with black. Young are light gray or tan, with distinct dark brown or black blotches on the back and sides; a black band passes between the eyes and angles down toward the mouth. After a year or two of growth, the color normally changes to a more uniform black.

Similar species: The closely related gray ratsnake (P. spiloides) occurs in southeast Missouri and hybridizes with the western ratsnake there. The gray ratsnake's adult coloration resembles the juvenile pattern of western ratsnakes: gray with dark blotches on back and sides, with a dark band passing through the eyes and angling down toward the mouth.

Size

Length: 42 to 72 inches (3½ to 6 feet).

western_ratsnake_on_leaves_1-2-15.jpg

Photo of a western ratsnake on a bed of dry leaves.
Western Ratsnake (Black Rat Snake)
The western ratsnake was long known as the black rat snake, and many know it simply as "black snake."

western_ratsnake_closeup_1-2-15.jpg

Photo of a western ratsnake, closeup of head.
Western Ratsnake (Black Rat Snake)
Western ratsnakes are natural, nonvenomous hunters of rodents, reducing damage to crops and stored grain.

western_ratsnake_10-28-11.jpg

Photo of a western ratsnake climbing in a tree.
Western Ratsnake (Black Rat Snake)
Western ratsnakes are excellent climbers and often bask in trees.

Western_Ratsnake_climbing_wall_Springfield_MO

Western Ratsnake climbing an exterior stone wall
Western Ratsnake Climbing A Wall
This western ratsnake was photographed climbing up the side of a building in Springfield, Missouri.
Habitat and conservation

Western ratsnakes live in a wide variety of habitats: rocky, wooded hillsides, wooded areas along streams and rivers (especially in former prairie and savanna areas of the state), and in or near farm buildings. They take shelter in brushpiles, hollow trees, farm buildings, and old houses where mice are plenty. They are excellent climbers and often bask in trees. They overwinter in mammal burrows, rock outcrops, old rock quarries, and other places, including rotted stumps or root systems of dead trees.

Foods

Western ratsnakes eat a variety of rodents, small rabbits, bats, bird eggs, small birds, and, on occasion, lizards. Prey is killed by constriction. They are excellent climbers and often climb trees to raid bird nests (including bluebird boxes) for eggs and young. Young western ratsnakes eat frogs, lizards, and insects.

Western Ratsnake dist map
Distribution in Missouri

Statewide. It may intergrade (hybridize) with the gray ratsnake (Pantherophis spiloides) in the southeastern corner. There is some evidence that this species is being replaced by the gray ratsnake in our Bootheel counties.

Status

Common. This species was long known as the black rat snake, and many know it simply as "black snake." Recent research has led scientists to reclassify this species in relation to its relatives, so its name has changed accordingly. Herpetologists, like ornithologists, carefully apply common names that correspond exactly to the scientific names. When scientific names change, the common names usually change, too.

Life cycle

This species is active in early April through early November. In spring, early summer, and autumn, they hunt in the daytime; in hot weather, they are nocturnal. Courtship and mating is usually in spring but also occurs in summer and fall. Eggs, usually 6–30, are laid in June or early July in rotten stumps or logs, sawdust piles, or under rocks. Eggs hatch in autumn.

Human connections

Only someone who has dealt with a mouse or rat problem can truly appreciate this natural, nonvenomous hunter of rodents. These snakes reduce damage to crops and stored grain by rodents without the use of deadly poisons. This far outweighs the occasional theft of a few hens' eggs or baby chickens.

Ecosystem connections

As a predator, this snake helps keep populations of other animals, especially rodents, in check. Although it can defend itself by trying to bite, by vibrating its tail ominously, and by smearing a stinky musk on attackers, this snake often becomes food for hawks and other predators.