Eastern rat snake

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Eastern ratsnake
Yellow Rat Snake (Elaphe obsoleta quadrivittata) (24209659368).jpg
Adult eastern ratsnake
McIntosh County, Georgia
Status TNC G4.svg
Apparently Secure  (NatureServe) [2]
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Colubridae
Genus: Pantherophis
Species:
P. quadrivittatus
Binomial name
Pantherophis quadrivittatus
(Holbrook, 1836) [3]
Synonyms
  • Coluber quadrivittatus
    Holbrook, 1836
  • Coluber obsoletus
    Boulenger, 1894 (part) [4]
  • Elaphe obsoleta
    Stejneger & Barbour, 1917 (part) [5]
  • Elaphe alleghaniensis
    Burbrink, 2001 [6]
  • Scotophis alleghaniensis
    Collins & Taggart, 2008 [7]
  • Pantherophis alleghaniensis
    Pyron & Burbrink, 2009
  • Pantherophis quadrivittatus
    — Burbrink, 2021

Pantherophis quadrivittatus, [8] commonly called the eastern rat snake, is a species of nonvenomous snake in the family Colubridae. The species is endemic to North America. [8]

Contents

Etymology

The generic name Pantherophis, meaning "panther-like snake", is from Ancient Greek : πάνθηρ: pánthēr, "panther" and Ancient Greek : ὄφις: óphis, "snake".

The specific name name quadrivittatus, meaning "four-banded", is from Latin : vitta meaning "band" in reference to the four dark stripes running the length of the snake's body.

Common names

Additional common names for Pantherophis quadrivittatus include black rat snake, pilot snake, pilot black snake, [9] chicken snake; and in Florida, yellow rat snake and Everglades rat snake. [10]

Geographic range

Pantherophis quadrivittatus is found in the United States east of the Apalachicola River in Florida, east of the Piedmont in Maryland, South Carolina, North Carolina, Georgia, and south to the Florida Keys. [8] In the Florida Panhandle, it readily hybridizes with the gray rat snake (Pantherophis alleghaniensis). [10] [8]

Description

Yellow rat snake, Pantherophis quadrivittatus in Florida Pantherophis alleghaniensis ssp. quadrivittata 03.JPG
Yellow rat snake, Pantherophis quadrivittatus in Florida

Adult eastern rat snakes commonly measure 90 to 183 cm (2 ft 11 in to 6 ft 0 in) in total length (including tail), with a few exceeding 200 cm (6 ft 7 in). [10] The longest recorded total length to date for an eastern rat snake is 228 cm (7 ft 6 in). [9] A sample of eastern rat snakes, including juvenile and adult snakes, weighed from 54 to 1,274 g (0.119 to 2.809 lb). [11] A further adult weighed 833 g (1.836 lb). [12]

Adults in the north of its range are shiny black dorsally, with a cream or white chin and throat. White areas of skin can appear between scales. The belly has an irregular black-and-white checkerboard pattern, becoming uniformly slate gray towards the tail. Juveniles have 28 to 40 [13] dark dorsal blotches on a grayish ground color. The ventral pattern in juveniles is the same as in adults. The eyes are round with a black pupil, with particularly in juveniles, but not always present in adults, a distinct white margin. [9] [14]

In the Florida Peninsula, adult rat snakes can be yellow, orange, tan, or gray, with four dark, longitudinal stripes. [15]

In cross section, the bodies of rat snakes are not round, but instead resemble a loaf of bread. [16]

The dorsal scales are weakly keeled, and are arranged in 23 to 27 rows at midbody. [17]

Males and females have the same coloration. Males have proportionally longer tails (16–19% of total body length) compared to females (14–18% of total body length). [9]

Habitat

The eastern rat snake occurs in a variety of habitats, including farmlands, hardwood forests, forested wetlands, thickets and fields adjacent to forests, isolated urban woodlots, and backyards that support populations of prey species. The eastern rat snake does especially well in early successional and edge habitats. An arboreal species, it can get into human residences, where it may live in attics undetected. At the northern limits of its range, distribution appears to be restricted by the availability of suitable hibernating sites. In these climates, it requires southern exposures to receive maximal thermal benefit from the winter sun and to provide basking areas in early spring and late fall. [14]

Behavior and ecology

The eastern rat snake is primarily active at night during the summer, and diurnal in the spring and fall. [18] It is a terrestrial burrower and an excellent climber, and it may enter water. It is found under rocks and boards, and in trees under bark and within knotholes and palm fronds. Eastern rat snakes have been found using water-filled cavities in trees, with many using the cavities at the same time. Gravid females were also four times more likely to use the water cavities than non-gravid females or male ratsnakes. [19] Gravid females prefer edge habitat more extensively than males and non-gravid females, this is because of the need for gravid females to retain higher body temperature. [20] The snake is a constrictor, and adults eat mainly endotherms, while young eat mainly ectotherms. The diet includes rodents, lizards, frogs, and birds and their eggs. [2] The snakes can also eat young chickens and chicks, hence the common name chicken snake.

Rat snakes are most vulnerable to predators as juveniles. Predators of P. quadrivittatus include hawks (Buteo spp.), great horned owls (Bubo virginianus), foxes, raccoons, and domestic cats. Adult eastern rat snakes have few known predators other than humans. When frightened, a rat snake will freeze. If harassed, it will produce a foul-smelling musk to deter predators. If provoked further, it may coil, shake its tail, and snap at its attacker. [21]

Eastern rat snakes hibernate during the winter underground or in deep crevices. They may congregate in the same dens with other species of snakes, such as copperheads (Agkistrodon contortrix), eastern racers (Coluber constrictor) and timber rattlesnakes (Crotalus horridus). In northern climes, the snakes are active from late April to October and mate in May or June. They are active earlier in the south. [22]

Reproduction

Eastern rat snakes are oviparous, and gaining nutrients for eggs is facilitated by the female maintaining her body temperature. [20] They reach sexual maturity in their fourth year. [23] The snakes start to breed in May and June, earlier in the south. Males approach females to initiate breeding, and may fight other males before breeding. About five weeks after mating, the female lays five to 27 eggs in hollow standing and fallen trees, compost and mulch heaps, sawdust piles, and decomposing logs. Incubation is about two months, and eggs hatch from July through September. Hatchlings are usually just over a foot long at birth, with the distinct gray-and-black pattern characteristic of juveniles. [18] [21] [22]

Juvenile eastern rat snake showing its grey base color with dark blotches Juvenile ratsnake crop.jpg
Juvenile eastern rat snake showing its grey base color with dark blotches

Taxonomy

Pantherophis quadrivittatus has sometimes been considered a subspecies of P. obsoletus , to which it is closely related. [24]

Opportunistic yellow rat snake looking for prey atop live oak tree Yellow Rat Snake 377.jpg
Opportunistic yellow rat snake looking for prey atop live oak tree

This species has often been placed in the genus Elaphe , but recent phylogenetic analyses have resulted in its transfer to Pantherophis. [3] [25] [26]

Previously, the eastern rat snake was assigned the binomial Pantherophis alleghaniensis and was thought to occupy the entire eastern seaboard north to Massachusetts. In 2021, genetic analysis found that the holotype for P. allegheniensis belongs to the species then known as Pantherophis spiloides, commonly called the central or gray rat snake. This species is now known to occupy a range between the Mississippi River in the west and the Piedmont in the east, north to New England. Due to the principle of priority, P. spiloides was reassigned to P. alleghaniensis. Therefore, the eastern rat snake, the species distributed east and south of the Piedmont and on the Florida Peninsula, was reassigned to what had been the junior synonym Pantherophis quadrivittatus. [8]

References

  1. Hammerson, G.A. (2019). "Pantherophis alleghaniensis". IUCN Red List of Threatened Species . 2019: e.T90069536A90069545. doi: 10.2305/IUCN.UK.2019-2.RLTS.T90069536A90069545.en . Retrieved 9 February 2025.
  2. 1 2 "Pantherophis alleghaniensis ". Nature Serve. Nature Server Explorer: An Online Encyclopedia of Life. Retrieved 2015-07-10.
  3. 1 2 Utiger U; Helfenberger N; Schätti 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)" (PDF). Russian Journal of Herpetology. 9 (2): 105–124.
  4. Boulenger GA (1894). Catalogue of the Snakes in the British Museum (Natural History). Volume II., Containing the Conclusion of the Colubridæ Aglyphæ. London: Trustees of the British Museum (Natural History). (Taylor and Francis, printers). xi + 382 pp. + Plates I-XX. (Coluber obsoletus, pp. 50-51).
  5. Stejneger L, Barbour T (1917). A Check List of North American Amphibians and Reptiles. Cambridge, Massachusetts: Harvard University Press. 125 pp. (Elaphe obsoleta, p. 83).
  6. Burbrink FT (2001). "Systematics of the eastern ratsnake complex (Elaphe obsoleta)". Herpetological Monographs. 15: 1–53. doi:10.2307/1467037. JSTOR   1467037.
  7. Collins, Joseph T.; Taggart, Travis W. (2008). "An alternative classification of the New World Rat Snakes (genus Pantherophis[Reptilia: Squamata: Colubridae])" (PDF). Journal of Kansas Herpetology. 26: 16–18.
  8. 1 2 3 4 5 Burbrink, Frank T. (2021). "The Corrected Taxonomic History of the North American Ratsnakes (Pantherophis obsoletus Complex)". Herpetological Review . 52 (3): 537–547 via Semantic Scholar.
  9. 1 2 3 4 "Eastern Ratsnake: Pantherophis alleghaniensis " (PDF). Massachusetts Division of Fisheries & Wildlife. Westborough, MA. Retrieved 2015-07-08.
  10. 1 2 3 "Pantherophis alleghaniensis ". Florida Museum of Natural History. Gainesville, FL. Retrieved 2015-07-09.
  11. Penning DA; Moon BR (2017). "The king of snakes: performance and morphology of intraguild predators (Lampropeltis) and their prey (Pantherophis)". Journal of Experimental Biology. 220 (6): 1154–1161. Bibcode:2017JExpB.220.1154P. doi:10.1242/jeb.147082. PMID   28298469.
  12. Veilleux J; Dombrowski DS; Allender MC; Lewbart G (2020). "Diagnosis, treatment and post-release monitoring of an eastern black rat snake (Pantherophis alleghaniensis) with ophidiomycosis and traumatic injuries". Veterinary Record Case Reports. 8 (2): e000954. doi:10.1136/vetreccr-2019-000954.
  13. "Black Ratsnake". www.marshall.edu. Retrieved 2023-04-22.
  14. 1 2 "Field Guide to Maryland's Snakes (Order Squamata): Eastern Ratsnake". Maryland Department of Natural Resources. Annapolis, MD. Retrieved 2015-07-08.
  15. "Eastern Ratsnake". Florida Snake ID Guide. Retrieved 2025-02-24.
  16. "Black Ratsnake". www.marshall.edu. Retrieved 2023-04-22.
  17. "Pantherophis alleghaniensis". Pennsylvania Herp Identification.
  18. 1 2 Behler, John L.; King, F. Wayne (1979). National Audubon Society Field Guide to North American Reptiles and Amphibians . Audubon Society Field Guide Series. New York, NY: Knopf Doubleday Publishing Group. ISBN   978-0-394-50824-5.
  19. Cerreta, Anthony J.; Cannizzo, Sarah A.; Smith, Dustin C.; Minter, Larry J. (2020-02-14). "Venous hematology, biochemistry, and blood gas analysis of free-ranging Eastern Copperheads (Agkistrodon contortrix) and Eastern Ratsnakes (Pantherophis alleghaniensis)". PLOS ONE. 15 (2): e0229102. Bibcode:2020PLoSO..1529102C. doi: 10.1371/journal.pone.0229102 . ISSN   1932-6203. PMC   7021292 . PMID   32059022.
  20. 1 2 Blouin-Demers, G.; Weatherhead, P.J. (2001). "HABITAT USE BY BLACK RAT SNAKES ( ELAPHE OBSOLETA OBSOLETA ) IN FRAGMENTED FORESTS". Ecology. 82 (10): 2882-2896. doi:10.1890/0012-9658(2001)082[2882:HUBBRS]2.0.CO;2.
  21. 1 2 "Black Rat Snake". The Maryland Zoo. Baltimore, MD. Retrieved 2015-07-10.
  22. 1 2 "Eastern Ratsnake (Pantherophis alleghaniensis)". Virginia Herpetological Society. Retrieved 2015-07-10.
  23. Fitch, H.S. (1963). "Natural History of the Black Rat Snake (Elaphe o. obsoleta) in Kansas". Copeia. 1963 (4): 649–658. doi:10.2307/1440967. JSTOR   1440967.
  24. "Pantherophis". SSARHerps. Archived from the original on 2011-10-30.
  25. Burbrink FT, Lawson R (2007). "How and when did Old World ratsnakes disperse into the New World?". Molecular Phylogenetics and Evolution. 43 (1): 173–189. Bibcode:2007MolPE..43..173B. doi:10.1016/j.ympev.2006.09.009. PMID   17113316.
  26. 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. Bibcode:2009MolPE..52..524P. doi:10.1016/j.ympev.2009.02.008. PMID   19236930.

Further reading