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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). Rat snakes are covered with keeled scales. They have a powerful slender body with a wedge-shaped head (Mattison 1990). These snakes come in a variety of subspecies. The black rat snake is the one most commonly found in Michigan.
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)
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).
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)
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. Males tend to wait for the females to pass through their territory. They communicate using pheromones.
Five weeks after mating, the female will lay around 12 to 20 eggs. 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.
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)
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)
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)
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)
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)
Patrick Trepanowski, Michigan State University
James Harding, Michigan State University
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..