Pantherophis obsoletusEastern Rat Snake

Geographic Range

Rat snakes are found from New England south through Florida and west through the eastern halves of Texas and Nebraska and north again to southern Wisconsin (Staszko and Walls 1994). Elaphe obsoleta obsoleta (Black Rat Snake) is the most widely distributed common rat snake with a range from New England south through Georgia and west across the northern parts of Alabama, Mississippi, and Louisiana, and north through Oklahoma to southern Wisconsin. There is also an isolated population in southern Canada and northern New York. E. o. quadrivittata (Yellow Rat Snake) is found along the coast of the Carolinas south through Georgia and Florida. E. o. rossalleni (Everglades Rat Snake) has an isolated population in southern Florida, hence, where the Everglades are located. E. o. spiloides (Gray Rat Snake) ranges from southern Georgia and northern Florida west through Mississippi and north to southern Kentucky. E. o. lindheimerii (Texas Rat Snake) can be found in southern Oklahoma, Texas, and Louisiana (Conant and Collins 1998).

Habitat

Common rat snakes live in a variety of habitats because each subspecies prefers a slightly different habitat. Some of these habitats overlap with one another. Common rat snakes are excellent climbers and will spend a lot of time in trees. Black rat snakes live at all elevations, from sea level to altitudes in the Appalachian Mountains. The black rat snakes lives in habitats ranging from a rocky hillside of mountains to flat farmland. The yellow rat snake is well established, living in oak hammocks, cut-over woods, fields, and around barns and abandoned houses. However, yellow rat snakes prefer a life in river swamps of the South, where they live high in cypress and other trees. Gray rat snakes replace the black rat snake in southern habitats suitable for black rat snakes. The Texas rat snake's habitat ranges from bayou and swampy areas to woods and stream valleys to rocky canyons. The Everglades rat snake makes its home in the Kissimmee Prairie and the Florida Everglades. In this habitat they can be found in trees and shrubs along the waterways, in the sawgrass, and on open prairies. (Conant and Collins 1998)

Physical Description

The common rat snake is medium-sized, averaging 42-72 inches (106.7-183 cm) in length (Conant and Collins 1998). At the widest point of the snake's body, the average diameter is 1.5 inches (3.8 cm) (Staszko and Walls 1994). Covered with keeled scales, common rat snakes have a powerful slender body with a wedge-shaped head (Mattison 1990). At the middle of the snake's body, there are 29 or fewer scale rows. In most rat snakes, there are 8 supralabials, and over 220 ventral scales, with 70 to 100 subcaudals (Staszko and Walls 1994). The anal plate (scale) of the common rat snake is divided. These snakes come in a variety of subspecies, each of which will be briefly described here.

The black rat snake, as the name states, is completely black except for their white chin. Hatchlings of the black rat snake have a pale grey background with black blotches along its back. As the snake matures, the color becomes darker until the snake reaches its adult phase. (Conant and Collins 1998)

The yellow rat snake has four well-defined longitudinal stripes extending down the length of its back. The base color varies from dull to bright yellow. The tongue, of the yellow rat snake, is black. Hatchlings are similar to those of the black rat snake, however, as the hatchlings mature, the dark spots fade as the yellow coloration and longitudinal stripes become more prominent. (Conant and Collins 1998)

The Everglades rat snake has a bright orange ground color. In some specimens, the color may appear more orange-yellow. This rat snake has grayish longitudinal stripes, which are not well defined and are often hard to see. The tongue is red. Juvenile Everglades rat snake are a pinkish color. (Conant and Collins 1998)

The gray rat snake keeps the blotched juvenile pattern its entire life. The blotches will vary between dark gray and brown. Juvenile black and yellow rat snakes are often mistaken as juvenile gray rat snakes. (Conant and Collins 1998)

The Texas rat snake is similar to the gray rat snake, however the blotches are usually less defined. The head of the Texas rat snake is often black. The juveniles of this subspecies have a much darker gray ground color. (Conant and Collins 1998)

Reproduction

Like most snakes, rat snakes are egg layers. Between March and May, snakes will begin to emerge from the winter's hibernation. After a few weeks, the common rat snakes will begin to seek out a mate, typically in late April, May, and early June (Rossi 1992). Males tend to wait for the females to pass through their territory, and by using pheromones, will communicate and initiate the mating process with the female (Rossi 1992). The male snake will approach the female, line up with her and attempt to wrap his tail around hers with their vents nearly touching. Some males will grasp the female, with his mouth, to hold her in place and prevent her from trying to move away. The male will then erect his hemipene and insert it into the female's cloaca while several small spines anchor the hemipene firmly (Staszko and Walls 1994). Mating can last only a few minutes or it can span the time of a few hours. Five weeks later, the female will lay around 12 to 20 eggs (Mattison 1990). The female will lay her eggs in a hidden area, under hollow logs or leaves, or in abandoned burrows. The eggs will hatch 65 to 70 days later. The hatchlings of common rat snakes are vigorous eaters and will double their size rather quickly. If conditions are good, females will sometimes produce two clutches of eggs a year. (Mattison 1990)

  • Range number of offspring
    12 to 20
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    1460 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    1460 days
    AnAge

Lifespan/Longevity

  • Average lifespan
    Status: captivity
    33.9 years
    AnAge

Behavior

Common rat snakes tend to be shy and, if possible, will avoid being confronted. If these snakes are seen and confronted by danger, they tend to freeze and remain motionless. There are those adults who will attempt to protect themselves. They will coil their body and vibrate their tails in dead leaves to simulate a rattle. If the snakes continue to get provoked, they will strike. Rat snakes produce a foul-smelling musk and will release it on the predator if they are picked up. The snake will then spread the musk around with their tail. The musk acts as a deterrent. A few of the rat snake sub-species tend to be more aggressive. The Texas rat snake and the black rat snake are very snappy, while the yellow rat snake is more passive. When alarmed, the Everglades rat snake will swim away through the swampy waters. (Harding 1997, Mattison 1990)

Food Habits

Rat snakes are primarily known as rodent eaters, however, other food preferences do exist. As juveniles, rat snakes will eat small lizards, baby mice, and an occasional small frog. Adult rat snakes have a diet mainly consisting of mice and rats, but will also include chipmunks, moles, and other small rodents. Adults will also eat bird eggs and young birds that do not put up a strong fight. Rat snakes kill their prey by constriction. (Rossi 1992)

Economic Importance for Humans: Positive

Rat snakes are very useful around barns and in the farming community. These snakes should be welcome on farms because they help control the pest population (rodents). (Harding 1997)

Conservation Status

The subspecies Elaphe obsoleta obsoleta is listed as special concern in the state of Michigan. Their habitat is slowly being reduced due to land development and the cutting of trees. However, they continue to maintain a healthy population in many areas. Due to people's lack of knowledge and fear of snakes, rat snakes continue to be the victim of human persecution. (Harding 1997)

Other Comments

Rat snakes are very popular and easy to obtain in the pet trade. Since they tend to have a passive demeanor, rat snakes are well liked by beginning and expert herp collectors. Almost all species are now bred in captivity. (Mattison 1990)

Contributors

Patrick Trepanowski (author), Michigan State University, James Harding (editor), Michigan State University.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

native range

the area in which the animal is naturally found, the region in which it is endemic.

taiga

Coniferous or boreal forest, located in a band across northern North America, Europe, and Asia. This terrestrial biome also occurs at high elevations. Long, cold winters and short, wet summers. Few species of trees are present; these are primarily conifers that grow in dense stands with little undergrowth. Some deciduous trees also may be present.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5? N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

References

Conant, R., J. Collins. 1998. Reptiles and Amphibians Eastern/Central North America. New York: Houghton Mifflin Company.

Harding, J. 1997. Amphibians and Reptiles of the Great Lakes Region. Ann Arbor: The University of Michigan Press.

Mattison, C. 1990. A-Z of Snake Keeping. New York: Sterling Publishing Co., Inc..

Rossi, J. 1992. Snakes of the United States and Canada Keeping Them Healthy in Captivity Volume I Eastern Area. Malabar, Florida: Krieger Publishing Company.

Staszko, R., J. Walls. 1994. Rat Snakes A Hobbyist's Guide to Elaphe and Kin. Neptune City, New Jersey: T.F.H. Publications, Inc..