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 familyColubridae. 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”.
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 genusPantherophis 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. 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.
Description
Adults of P. obsoletus can become quite large, with a reported typical total length (including tail) of 106.5–183cm (3ft 6in– 6ft 0in).[7][8] It is the largest snake found in Canada. The record total length is 256.5cm (8ft 5in),[9] making it (officially) the longest snake in North America.[8] 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 (2.8m).[citation needed] The body mass of P. obsoletus can range up to 0.5 to 2.2kg (1.1 to 4.9lb) 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 1kg (1.7 and 2.2lb).[10][11][12]
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.[13][14]
Common names
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]
Behavior
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).[15] 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.[16] 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 150cm (59in) 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.[17][18]
Feeding
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.[13][19] One snake was observed to consume an entire clutch of mallard eggs.[15] 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.[20]
Reproduction
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 36–60mm (1.4–2.4in) long by 20–26.5mm (0.79–1.04in) wide. The eggs hatch about 65 to 70 days later in late August to early October.[21] The hatchlings are 28–41cm (11–16in) in total length,[4] and they look like miniature fox snakes.[13]
Taxonomy
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.[22] In addition, because Pantherophis is masculine, the specific epithet becomes the masculine obsoletus.[23] The split of Pantherophis from Elaphe has been further confirmed by additional phylogenetic studies.[24][25]
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.[26] More recent investigations have indicated P. alleghaniensis and P. spiloides interbreed freely in Ontario.[27]
In 2008, Collins and Taggart[28] 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.[24] The justification for this nomenclatural change has been removed by more recent research.[25]
In captivity
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.
Related Research Articles
Rat snakes are members – along with kingsnakes, milk snakes, vine snakes and indigo snakes – of the subfamily Colubrinae of the family Colubridae. They are medium to large constrictors and are found throughout much of the Northern Hemisphere. They feed primarily on rodents. Many species make attractive and docile pets and one, the corn snake, is one of the most popular reptile pets in the world. Like all snakes, they can be defensive when approached too closely, handled, or restrained. However, rat snake bites are not dangerous to humans. Like nearly all colubrids, rat snakes pose no threat to humans. Rat snakes were long believed to be completely nonvenomous, but recent studies have shown that some Old World species do possess small amounts of venom, though the amount is negligible relative to humans.
The corn snake, sometimes called red rat snake, is a species of North American rat snake in the family Colubridae. The species subdues its small prey by constriction. It is found throughout the southeastern and central United States. Though superficially resembling the venomous copperhead and often killed as a result of this mistaken identity, the corn snake lacks functional venom and is harmless. The corn snake is beneficial to humans because it helps to control populations of wild rodent pests that damage crops and spread disease.
The gray ratsnake or gray rat snake, also commonly known as the central ratsnake, chicken snake, midland ratsnake, or pilot black snake, is a species of nonvenomous snake in the genus Pantherophis in the subfamily Colubrinae. The gray ratsnake is one of about ten species within the American ratsnake genus Pantherophis.
Elaphe is a genus of snakes in the family Colubridae. Elaphe is one of the main genera of the rat snakes, which are found in many regions of the northern hemisphere. Elaphe species are medium to large constrictors by nature. Although all of the species in Elaphe are nonvenomous, bites from rat snakes are still irritably painful and can potentially cause bacterial infections, especially due to the saliva.
Pantherophis is a genus of nonvenomous colubrid snakes endemic to central and eastern regions of North America. It consists of the North American ratsnakes, the foxsnakes, and the cornsnakes. The genus, which contains 10 recognized species, first appeared in the fossil record in the Middle Miocene around 16.3 million years ago. They are a large terrestrial snake genus that lack subocular scales. Originally classified in the genus Elaphe, phylogenetic studies have found this taxon to be closely related to Pituophis. As with all snakes Pantherophis is an obligate faunivore with a diet that consists of small mammals, birds, reptiles and amphibians, and even insects. While many species conservation status is categorized as "least concern", many local populations in some species have declined where some places have them listed as federally protected. The corn snake is a popular pet reptile, due to the availability of captive-bred animals, their low maintenance and calm disposition, and the variety of color morphs. There are other species of Pantherophis that are in the pet trade, though are not as popular as the corn snake.
The mandarin rat snake is a species of nonvenomous colubrid snake endemic to Asia. It is closely related to Euprepiophis conspicillata, the Japanese forest rat snake. Mandarin rat snakes are one of the most popular rat snakes found in the pet trade.
The eastern trinket snake is a species of snake in the family Colubridae. The species is endemic to South Asia.
Pantherophis vulpinus, commonly known as the foxsnake or the eastern fox snake, is a species of nonvenomous rat snake in the family Colubridae. The species is native to North America.
The Trans-Pecos rat snake or Davis Mountain rat snake, is a species of medium to large, nonvenomous rat snake in the family Colubridae. Bogertophis subocularis is endemic to the Chihuahuan Desert.
The eastern racer, or North American racer, is a species of nonvenomous snake in the family Colubridae. The species is endemic to North America and Central America. Eleven subspecies, including the nominotypical subspecies, are recognized, which as a group are commonly referred to as the eastern racers. The species is monotypic in the genus Coluber.
The Texas rat snake is a subspecies of the black rat snake, a nonvenomous colubrid. It is found in the United States, primarily within the state of Texas, but its range extends into Louisiana, Arkansas and Oklahoma. It intergrades with other subspecies of Elaphe obsoleta, so exact range boundaries are impossible to distinguish. The epithet lindheimeri is to honor the German-American naturalist Ferdinand Jacob Lindheimer, who collected the first specimen in New Braunfels, Texas.
Pantherophis emoryi, commonly known as the Great Plains rat snake, is a species of nonvenomous rat snake in the family Colubridae. The species is native to the central part of the United States, from Missouri to Nebraska, to Colorado, south to Texas, and into northern Mexico.
Pantherophis bairdi is a species of harmless snake in the family Colubridae. The species is native to the southwestern United States and adjacent northeastern Mexico. No subspecies are recognized as being valid.
Black rat snake may refer to:
Euprepiophis conspicillata, commonly known as the Japanese forest rat snake, is a species of nonvenomous colubrid snake endemic to Japan. Its Japanese common name, jimuguri, roughly translates to "the burrower". It is closely related to Euprepiophis mandarinus, the Mandarin rat snake.
Elaphe quadrivirgata, commonly known as the Japanese four-lined ratsnake or the Japanese striped snake, is a species of non-venomous colubrid snake native to Japan.
Slowinski's corn snake is a subspecies of nonvenomous snake in the family Colubridae. The subspecies is indigenous to Louisiana, eastern Texas, and Arkansas.
Pantherophis alleghaniensis, commonly called the eastern rat snake, is a species of nonvenomous snake in the family Colubridae. The species is endemic to North America.
The Transcaucasian ratsnake, also commonly known as the Gavand snake, is a species of nonvenomous ratsnake in the family Colubridae. The species is endemic to Western Asia and the Middle East.
Elaphe moellendorffi, commonly called the flower snake or Moellendorf's [sic] rat snake, is a species of snake in the family Colubridae. The species is endemic to southeastern Asia.
1 2 3 Wright AH, Wright AA (1957). Handbook of Snakes of the United States and Canada. Ithaca and London: Comstock. 1,105 pp. (in 2 volumes) (Seventh printing, 1985) ISBN0-8014-0463-0. (Elaphe obsoleta obsoleta, pp. 230-234, Figure 72 + Map 24 on p. 235).
↑ Powell R, Conant R, Collins JT (2016). Peterson Field Guide to Reptiles and Amphibians of Eastern and Central North America, Fourth Edition. Boston and New York: Houghton Mifflin Harcourt. xiv + 494 pp. ISBN978-0-544-12997-9. (Pantherophis obsoletus, p. 388 + Figure 161 on p. 334 + Plate 36 on p. 335 + Map on p. 385 + Figure 180 on p. 386).
↑ Conant R, Bridges W (1939). What Snake Is That? A Field Guide to the Snakes of the United States East of the Rocky Mountains. (with 108 drawings by Edmond Malnate). New York and London: D. Appleton-Century. Frontispiece map + viii + 163 pp. + Plates A-C, 1-32. (Elaphe obsoleta obsoleta, pp. 56-58 + Plate 8, Figure 23).
↑ "Snakes". Herpetological Education & Research Project. Retrieved 2015-05-21.
1 2 3 Schmidt KP, Davis DD (1941). Field Book of Snakes of the United States and Canada. New York: G.P. Putnam's Sons. xiii + 365 pp. (Elaphe obsoleta obsoleta, pp. 148-150, Figure 40 + Plate 16, center, on p. 336).
↑ Conant R (1975). A Field Guide to Reptiles and Amphibians of Eastern and Central North America, Second Edition. Boston: Houghton Mifflin. xviii + 429 pp. + Plates 1-48. ISBN0-395-19977-8 (paperback). (Elaphe obsoleta obsoleta, pp. 193-194 + Plate 28 + Map 149).
1 2 Pyron RA, Burbrink FT (2009). "Neogene diversification and taxonomic stability in the snake tribe Lampropeltini (Serpentes: Colubridae)". Molecular Phylogenetics and Evolution. 52 (2): 524–529. doi:10.1016/j.ympev.2009.02.008. PMID19236930.
↑ Burbrink FT (2001). "Systematics of the Eastern Ratsnake complex (Elaphe obsoleta)". Herpetological Monographs. 15: 1–53. doi:10.2307/1467037. JSTOR1467037.
↑ Gibbs, H. Lisle; Corey, Sarah J.; Blouin-Demers, Gabriel; Prior, Kent A.; Weatherhead, Patrick J. (2006). "Hybridization between mtDNA-defined phylogeographic lineages of black ratsnakes (Pantherophis spp.)". Molecular Ecology. 15 (12): 3755–3767. doi:10.1111/j.1365-294X.2006.03056.x. PMID17032272. S2CID3727973.
↑ Collins JT, Taggart TW (2008). "An alternative classification of the New World Rat Snakes (genus Pantherophis [Reptilia: Squamata: Colubridae])". Journal of Kansas Herpetology. 26: 16–18.
Further reading
Say T (1823). In:James E (1823). Account of an Expedition from Pittsburgh to the Rocky Mountains, Performed in the Years 1819 and '20, by Order of the Hon. J.C. Calhoun, Sec'y of War: Under the Command of Major Stephen H. Long. From the Notes of Major Long, Mr. T. Say, and other Gentlemen of the Exploring Party. Vol. I. Philadelphia: H.C. Carey and I. Lea. 503 pp. (Coluber obsoletus, new species, p.140).
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