Pantherophis obsoletus
| Western ratsnake | |
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| Conservation status | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Subphylum: | Vertebrata |
| Class: | Reptilia |
| Order: | Squamata |
| Suborder: | Serpentes |
| Family: | Colubridae |
| Subfamily: | Colubrinae |
| Genus: | Pantherophis |
| Species: | P. obsoletus |
| Binomial name | |
| Pantherophis obsoletus (Say in James, 1823) |
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| Synonyms | |
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The Western ratsnake (Pantherophis obsoletus) — also called black rat snake, pilot black snake, or simply black snake[2] — is a nonvenomous colubrid species found in North America. No subspecies are currently recognized.[3]
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[edit] Geographic range
The black rat snake is found throughout the Eastern and Central United States. In Canada it is found in lower Ontario. It is found in northeast United States, in particular New Jersey(northern), New York(eastern) and Vermont(southern).
[edit] Preferred habitat
It prefers heavily wooded areas and is known for having excellent climbing ability, including the ability to climb the trunk of large mature trees without the aid of branches. The black rat snake is a competent swimmer but usually (not always) uses this ability only to travel to additional hunting territory. During winter it hibernates in dens, often with copperheads and timber rattlesnakes. This association gave rise to the common name, pilot black snake, and the superstition that this nonvenomous species led the venomous ones to the den.
[edit] Description
Adults can become quite large and are known to reach up to eight feet, being the largest snake found in Canada. The record length is 101 inches (2.6 m), making it (officially) the longest snake in North America. Unofficially, indigo snakes (Drymarchon couperi) are known to exceed them, and one wild caught pine snake (Pituophis melanoleucus) with a portion of its tail missing measured 111 inches (2.8 m).[citation needed]
Juveniles are strongly patterned with brown blotches on a gray background (like miniature fox snakes). 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.[4][5]
[edit] Common names
Other common names include: Alleghany black snake, black chicken snake, black Coluber, black pilot snake, chicken snake, mountain black snake, mountain pilot snake, pilot, rat snake, rusty black snake, scaly black snake, cow snake, schwartze schlange, sleepy John, white-throated racer.[6]
[edit] Behavior
When startled, they may freeze and wrinkle themselves into a series of kinks. If they feel further threatened, they may flee quickly or vibrate their tails in dead leaves (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 a predator if picked up. They spread the musk with their tail in hopes of deterring the threat.[7]
[edit] Feeding
This species is a constrictor, meaning it suffocates its prey, coiling around small animals and tightening its grip until they can no longer draw breath, before eating them. Though they do consume mice and rats, black rat snakes will also hunt other snakes, frogs, lizards, chipmunks, squirrels, juvenile rabbits, juvenile opossums, song birds, and bird eggs.[8]
[edit] Reproduction
.JPG)
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, cloaca. The mating lasts anywhere from 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 in.) long by 20-26.5 mm (0.8-1.1 in.) wide. The eggs hatch about 65 to 70 days later in late August to early October.[9] The hatchlings are 28–41 cm (11-16 in.) in total length,[10] and they look like miniature fox snakes.[11]
[edit] 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 as broadly construed is paraphyletic, and placed this species in the genus Pantherophis[12]. In addition, because Pantherophis is masculine, the specific epithet becomes the masculine obsoletus.[13] The split of Pantherophis from Elaphe has been further confirmed by additional phylogenetic studies[14][15].
In 2001 Burbrink suggested that this species be divided into three species based on geographic patterns of mitochondrial DNA diversity[16]. 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), Western ratsnake (E. obsoleta, now P. obsoletus). However, these three species are not morphologically distinct and overlap in all examined morphological characters[17]. More recent investigations have indicated that P. alleghaniensis and P. spiloides interbreed freely in Ontario[18].
In 2008 Collins and Taggart[19] 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[20]. The justification for this nomenclatural change has been removed by more recent research[21].
[edit] References
- ^ "Elaphe obsoleta". Natural Heritage Information Centre. Ontario Ministry of Natural Resources. http://nhic.mnr.gov.on.ca/MNR/nhic/elements/el_report.cfm?elid=180765. Retrieved October 19, 2010.
- ^ Wright AH, Wright AA. 1957. Handbook of Snakes. Comstock Publishing Associates. (7th printing, 1985). 1105 pp. ISBN 0-8014-0463-0.
- ^ "Elaphe obsoleta". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=174177. Retrieved 29 November 2006.
- ^ Schmidt, K.P. and D.D. Davis. 1941. Field Book of Snakes of the United States and Canada. G.P. Putnam's Sons. New York.
- ^ Conant, Roger. 1975. A Field Guide to Reptiles and Amphibians of Eastern and Central North America. Houghton Mifflin. Boston.
- ^ Wright, A.H. and A.A. Wright. 1957. Handbook of Snakes of the United States and Canada. Comstock. Ithaca and London.
- ^ Fact Sheet at Smithsonian National Zoological Park Website
- ^ Schmidt, K.P. & D.D. Davis. 1941. Field Book of Snakes of the United States and Canada. G.P. Putnam's Sons. New York.
- ^ Black snake profile at National Zoo website
- ^ Wright, A.H. & A.A. Wright. 1957. Handbook of Snakes of the United States and Canada. Comstock. Ithaca & London.
- ^ Schmidt, K.P. & D.D. Davis. 1941. Field Book of Snakes of the United States and Canada. G.P. Putnam's Sons. New TYork.
- ^ Utiger, U., N. Helfenberger, B. Schätti, C. Schmidt, M. Ruf, and V. Ziswiler, 2002. Molecular Systematics and Phylogeny of Old and New World ratsnakes, Elaphe Auct., and related genera (Reptilia, Squamata, Colubridae). Russian Journal of Herpetology 9(2): 105-124.
- ^ Elaphe obsoleta at The Center for North American Herpetology. Accessed 20 June 2008.
- ^ Burbrink, F. T. and R. Lawson, 2007. How and when did Old World ratsnakes disperse into the New World? Molecular Phylogenetics and Evolution 43: 173-189.
- ^ Pyron, R. A. and F. T. Burbrink, 2009. Neogene diversification and taxonomic stability in the snake tribe Lampropeltini (Serpentes: Colubridae) Molecular Phylogenetics and Evolution 52: 524-529.
- ^ Burbrink, F.T. 2001. Systematics of the Eastern Ratsnake complex (Elaphe obsoleta). Herpetological Monographs 15:1-53
- ^ Burbrink, F.T. 2001. Systematics of the Eastern Ratsnake complex (Elaphe obsoleta). Herpetological Monographs 15:1-53
- ^ Gibbs, H. L., S. J. Corey, G. Blouin-Demers, K. A. Prior, and P. J. Weatherhead, 2006. Hybridization between mtDNA-defined phylogeographic lineages of black ratsnakes (Pantherophis spp.). Molecular Ecology 15:3755-3767
- ^ Collins, J. T. & T. W. Taggart. 2008. An alternative classification of the New World Rat Snakes (genus Pantherophis [Reptilia: Squamata: Colubridae]). Journal of Kansas Herpetology 26:16-18
- ^ Burbrink, F. T. and R. Lawson, 2007. How and when did Old World ratsnakes disperse into the New World? Molecular Phylogenetics and Evolution 43: 173-189.
- ^ Pyron, R. A. and F. T. Burbrink, 2009. Neogene diversification and taxonomic stability in the snake tribe Lampropeltini (Serpentes: Colubridae) Molecular Phylogenetics and Evolution 52: 524-529.
[edit] Further reading
- Utiger U, Helfenberger N, Schatti B, Schmidt C, Ruf M, Ziswiler V. 2002. Molecular systematics and phylogeny of Old and New World ratsnakes, Elaphe Auct., and related genera (Reptilia, Squamata, Colubridae). Russian Journal of Herpetology 9(2):105-124.
[edit] External links
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Wikimedia Commons has media related to: Elaphe obsoleta |
- Pantherophis obsoletus at J. Craig Venter Institute. Accessed 25 October 2008
- Pantherophis obsoletus at the Reptarium.cz Reptile Database. Accessed 2 June 2008.
- Ratsnake - Elaphe obsoleta at HerpNet. Accessed 2 June 2008.
- E. obsoleta image at Picasa. Accessed 2 June 2008.
- Elaphe obsoleta populations in Southern Ontario Canada Accessed 17 October 2008.
- Black Rat Snake at Natural Resources Canada
- "Black Snakes": Identification and Ecology - University of Florida fact sheet
- Black Rat Snake (Elaphe obsoleta obsoleta), Natural Resources Canada
- Scientific and Standard English Names of Amphibians and Reptiles of North America North of Mexico, With Comments Regarding Confidence In Our Understanding. Edition 6.1
