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)
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)
US Federal List: no special status
CITES: no special status
State of Michigan List: special concern
IUCN Red List of Threatened Species: least concern
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)
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 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).
Biogeographic Regions: nearctic (Native )
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)
Terrestrial Biomes: taiga ; savanna or grassland ; forest
Average lifespan
Status: captivity: 33.9 years.
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)
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 (male)
Sex: male: 1460 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 1460 days.
Pantherophis obsoletus, also known commonly as the western rat snake, black rat snake, pilot black snake, or simply black snake,[4] is a nonvenomous species of snake in the family Colubridae. The species is native to central North America. There are no subspecies that are recognized as being valid.[5] Its color variations include the Texas rat snake.[3] 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”.
P. 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.[6]
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.
Rat snakes of the genus Pantherophis are 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.[7] 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 it hibernates in shared dens, often with copperheads and timber rattlesnakes. 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.
Adults of P. obsoletus can become quite large, with a reported typical total length (including tail) of 106.5–183 cm (3 ft 6 in – 6 ft 0 in).[8][9] It is the largest snake found in Canada. The record total length is 256.5 cm (8 ft 5 in),[10] making it (officially) the longest snake in North America.[9] Unofficially, indigo snakes (genus Drymarchon) are known to exceed it, and one wild-caught pine snake (Pituophis melanoleucus), with a portion of its tail missing, measured 111 inches (2.8 m). The body mass of P. obsoletus can range up to 0.5 to 2.2 kg (1.1 to 4.9 lb) in adults, although most adults are on the smaller end of this scale, per herpetology research sites, with weights most commonly between 0.77 and 1 kg (1.7 and 2.2 lb).[11][12][13]
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.[14][15]
Other common names for P. 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, schwartze Schlange, sleepy John, and white-throated racer.[4]
When not fully grown, rat snakes are subject to predation by many animals, including other snakes. Once they attain maturity, they are readily preyed on by mammalian carnivores (including the American mink, which weighs no more than an adult rat snake) and large birds of prey (especially red-tailed hawks).[16] When startled, they may freeze and wrinkle themselves into a series of kinks. If they feel further threatened, they may flee quickly or tail vibrate (potentially a form of mimicry, which makes them sound like rattlesnakes). They are also capable of producing a foul-smelling musk, which they will release onto predators if picked up. They spread the musk with their tails in hopes of deterring the threat.[17] When cornered or provoked, black snakes are known to stand their ground and can become aggressive. Counterattacks on large birds of prey, often committed by large snakes in excess of 150 cm (59 in) in length, have resulted in violent prolonged struggles. Utilizing its infamous agility and the great strength of its muscular coils, the black rat snake is sometimes able to overwhelm and kill formidable avian predators such as red-tailed hawks, great horned owls and red-shouldered hawks, though in many cases the bird is able to kill the snake and both combatants may even die.[18][19]
P. obsoletus is a constrictor, meaning it squeezes its prey to the point of cardiovascular collapse due to obstructive shock, coiling around small animals and tightening its grip until the prey can no longer circulate blood and dies of profound hypotension, before being eaten. Though it will often consume mice, voles, and rats, the western rat snake is far from a specialist at this kind of prey and will readily consume any small vertebrate it can catch. Other prey opportunistically eaten by this species can include other snakes (including both those of its own and other species), frogs, lizards, moles, chipmunks, squirrels, juvenile rabbits, juvenile opossums, songbirds, and bird eggs.[14][20] One snake was observed to consume an entire clutch of mallard eggs.[16] Cavity-nesting bird species are seemingly especially prevalent in this snake's diet. The western rat snake has been noted as perhaps the top predator at purple martin colonies as a single large snake will readily consume a number of eggs, hatchlings, and adults each summer. Several rat snake repelling methods have been offered to those putting up martin houses, but most are mixed in success.[21]
In P. obsoletus mating takes place in late May and early June. The male snake wraps its tail around the female with their vents nearly touching. The male then everts one of its sex organs, a hemipenis, into the female sex organ, the cloaca. The mating lasts a few minutes to a few hours. After five weeks, the female lays about 12 to 20 eggs, which are 36–60 mm (1.4–2.4 in) long by 20–26.5 mm (0.79–1.04 in) wide. The eggs hatch about 65 to 70 days later in late August to early October.[22] The hatchlings are 28–41 cm (11–16 in) in total length,[4] and they look like miniature fox snakes.[14]
This species has previously been placed (and is still placed by many) in the genus Elaphe, as Elaphe obsoleta. However, Utiger et al. found that Elaphe is broadly construed as paraphyletic, and placed this species in the genus Pantherophis.[23] In addition, because Pantherophis is masculine, the specific epithet becomes the masculine obsoletus.[24] The split of Pantherophis from Elaphe has been further confirmed by additional phylogenetic studies.[25][26]
In 2001, Burbrink suggested this species be divided into three species based on geographic patterns of mitochondrial DNA diversity. He assigned new common names and resurrected old scientific names, resulting in the following combinations: eastern ratsnake (Elaphe alleghaniensis, now Pantherophis alleghaniensis), central ratsnake (Elaphe spiloides, now Pantherophis spiloides), and western rat snake (Elaphe obsoleta, now Pantherophis obsoletus). However, these three species are not morphologically distinct and overlap in all examined morphological characters.[27] More recent investigations have indicated P. alleghaniensis and P. spiloides interbreed freely in Ontario.[28]
In 2008, Collins and Taggart[29] resurrected the genus Scotophis for Burbrink's three taxa (i.e., Scotophis alleghaniensis, Scotophis spiloides, and Scotophis obsoletus) in response to the findings of Burbrink and Lawson, 2007.[25] The justification for this nomenclatural change has been removed by more recent research.[26]
The western rat snake is available captive-bred in the United States pet trade, and it has been bred for mutations such as leucistic, albino, and scaleless. However, it is not as popular as other colubrids such as corn snakes, kingsnakes, milksnakes, and hognose snakes. Opinions vary on the western rat snake's disposition, but captive-bred individuals are reported to be more docile than their wild counterparts. With appropriate care, this species may be expected to live 15 years in captivity, and possibly more.[7]
Pantherophis obsoletus, also known commonly as the western rat snake, black rat snake, 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. There are no subspecies that 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”.
Black rat snake