Pantherophis alleghaniensis - (Holbrook, 1836)
Eastern Ratsnake
Other English Common Names: Eastern Ratsnake
Synonym(s): Elaphe alleghaniensis (Holbrook, 1836)
Taxonomic Status: Accepted
Related ITIS Name(s): Elaphe alleghaniensis (Holbrook, 1836) (TSN 683033)
Unique Identifier: ELEMENT_GLOBAL.2.103363
Element Code: ARADB13080
Informal Taxonomy: Animals, Vertebrates - Reptiles - Snakes
 
Kingdom Phylum Class Order Family Genus
Animalia Craniata Reptilia Squamata Colubridae Pantherophis
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Concept Reference
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Concept Reference: Burbrink, F. T. 2001. Systematics of the eastern ratsnake complex (Elaphe obsoleta). Herpetological Monographs 15:1-53.
Concept Reference Code: A01BUR01NAUS
Name Used in Concept Reference: Elaphe alleghaniensis
Taxonomic Comments: Burbrink et al. (2000) and Burbrink (2001) examined genetic and morphological variation in Elaphe obsoleta as traditionally defined and determined that the nominal subspecies do not represent evolutionary lineages and should no longer be recognized. Further, these authors identified three clades within E. obsoleta, corresponding to populations (1) west of the Mississippi River (western clade), (2) east of the Mississippi River and west of the Appalachian Mountains and Apalachicola River (central clade), and (3) east of the Appalachians and the Apalachicola River (eastern clade). Burbrink (2000) recognized the three clades as distinct species: E. obsoleta (western clade), E. spiloides (central clade), and E. alleghaniensis (eastern clade). In mapping the distribution of the species, Burbrink indicated a very large area of "taxonomic uncertainty" extending from New England to northern Georgia. In this region the distribution of E. alleghaniensis was deemed "somewhat questionable with regard to hybridization with members of Elpahe spiloides." Although Burbrink concluded that the molecular data show that E. alleghaniensis and E. spiloides represent independently evolving units with separate evolutionary histories and thus should be recognized as different species under the evolutionary species concept, contact zones were not critically examined, so the nature and dimensions of clade boundaries, and the precise distributions of alleghaniensis and spiloides along the length of the Appalachians, remain uncertain.

Elaphe bairdi, confirmed as a valid species by Burbrink (2001), was included in Elaphe obsoleta by some authors in older literature.

Utiger et al. (2002) examined mtDNA variation in New World and Old World "Elaphe" and determined that North American rat snakes currently included in the genus Elaphe form a monophyletic limeage that is distinct from Old World snakes that also have been regarded as Elaphe. They resurrected the genus Pantherophis for the rat snakes north of Mexico, including the following species: Pantherophis obsoletus (and P. alleghaniensis and P. spiloides, if one recognizes those taxa as species), P. guttatus, P. emoryi, P. vulpinus, P. gloydi, and P. bairdi. Based on mtDNA and nuclear DNA data, Burbrink and Lawson (2007) determined that New World Elaphe are not closely related to Old World Elaphe. Here we follow these studies and Crother (2008, 2012) and transfer New World Elaphe to the genus Pantherophis.
Conservation Status
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NatureServe Status

Global Status: G4G5
Global Status Last Reviewed: 14Apr2016
Global Status Last Changed: 14Apr2016
Rounded Global Status: G4 - Apparently Secure
Reasons: Large range in eastern North America; large area of occupancy; presumed large population size; trend uncertain: better information is needed on population impact of snake fungal disease. Better information is needed on distribution relative to Pantherophis spiloides.
Nation: United States
National Status: N4N5 (14Apr2016)
Nation: Canada
National Status: NNR

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Alabama (SNR), Connecticut (S4), Delaware (S5), District of Columbia (S3S5), Florida (SNR), Georgia (S5), Maryland (S5), Massachusetts (S1), New Jersey (SU), North Carolina (S5), Pennsylvania (S5), Rhode Island (S2), South Carolina (SNR), Vermont (S2), Virginia (S5), West Virginia (S5)

Other Statuses

NatureServe Global Conservation Status Factors

Range Extent: 200,000-2,500,000 square km (about 80,000-1,000,000 square miles)
Range Extent Comments: This species occurs in the eastern United States, from New England to southern Florida, east of the Appalachian Mountains, east of the Apalachicola River in Florida, and east of the Chattahoochee River in Georgia; western edge of range is poorly defined, and a large area of taxonomic uncertainty potentially involving hybridization with P. spiloides extends from eastern New York and New England to northern Georgia (Burbrink 2001). A ratsnake species has been introduced in the Bahamas (Abacos; Buckner and Franz, 1994, Herpetol. Rev. 25:166), but whether it represents this species or another is uncertain from information presented in the published record.

Area of Occupancy: 2,501 to >12,500 4-km2 grid cells
Area of Occupancy Comments: Area of occupancy is unknown but very large.

Number of Occurrences:  
Number of Occurrences Comments: The number of distinct occurrences has not been determined using consistent criteria, but this species is represented by a very large number of collection sites and locations (as defined by IUCN).

Population Size: 100,000 to >1,000,000 individuals
Population Size Comments: Total adult population size is unknown but very large (presumably exceeds 100,000) This species is locally common in much of its range.

Overall Threat Impact: Medium - low
Overall Threat Impact Comments: Intensive agricultural development and urbanization have caused localized declines, and collectors probably have depleted some easily accessible populations, but in most areas this snake is not threatened by these factors. This species is vulnerable to snake fungal disease; the scope, severity, and population impact of this disease on P. alleghaniensis are uncertain but potentially significant.

Short-term Trend: Decline of <30% to relatively stable
Short-term Trend Comments: Trend over the past 10 years or three generations is uncertain, but extent of occurrence, area of occupancy, number of subpopulations, and population size probably have been relatively stable or slowly declining (however, see threats comments).

Other NatureServe Conservation Status Information

Distribution
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Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) This species occurs in the eastern United States, from New England to southern Florida, east of the Appalachian Mountains, east of the Apalachicola River in Florida, and east of the Chattahoochee River in Georgia; western edge of range is poorly defined, and a large area of taxonomic uncertainty potentially involving hybridization with P. spiloides extends from eastern New York and New England to northern Georgia (Burbrink 2001). A ratsnake species has been introduced in the Bahamas (Abacos; Buckner and Franz, 1994, Herpetol. Rev. 25:166), but whether it represents this species or another is uncertain from information presented in the published record.

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map
Endemism: endemic to a single nation

U.S. & Canada State/Province Distribution
United States AL, CT, DC, DE, FL, GA, MA, MD, NC, NJ, PA, RI, SC, VA, VT, WV

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
MA Bristol (25005), Franklin (25011), Hampden (25013), Worcester (25027)
RI Washington (44009)
VT Addison (50001), Rutland (50021)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
01 Middle Connecticut (01080201)+, Westfield (01080206)+, Narragansett (01090004)+, Pawcatuck-Wood (01090005)+, Quinebaug (01100001)+
04 Mettawee River (04150401)+, Otter Creek (04150402)+, Lake Champlain (04150408)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Reproduction Comments: Lays eggs in early summer. Eggs in late summer. May lay two clutches annually in south. May lay eggs in communal nest.
Ecology Comments: Home range diameter at least 500-600 m in Maryland (DeGraaf and Rudis 1983).
Non-Migrant: Y
Locally Migrant: Y
Long Distance Migrant: N
Mobility and Migration Comments: May migrate in spring and fall between hibernaculum and summer range. Home range diameter was at least 500-600 m in Maryland (DeGraaf and Rudis 1983).
Palustrine Habitat(s): FORESTED WETLAND, Riparian
Terrestrial Habitat(s): Bare rock/talus/scree, Cliff, Cropland/hedgerow, Forest - Conifer, Forest - Hardwood, Forest - Mixed, Old field, Savanna, Suburban/orchard, Woodland - Conifer, Woodland - Hardwood, Woodland - Mixed
Special Habitat Factors: Burrowing in or using soil, Fallen log/debris, Standing snag/hollow tree
Habitat Comments: Habitat includes hardwood forest and woodland, wooded canyons, swamps, rocky timbered upland, wooded areas of streams and rivers, farmland near woods, old fields, barnyards, rural buildings. This species often occurs where wooded and open habitats (such as fields or farmland) are intermixed. It is terrestrial and also often climbs trees; may enter water. Hibernation occurs in deep crevices, or underground.
Adult Food Habits: Carnivore
Immature Food Habits: Carnivore
Food Comments: Eats birds and their eggs, small mammals, lizards, frogs, and invertebrates; adults eat mainly endotherms while young eat mainly ectotherms.
Adult Phenology: Crepuscular, Diurnal, Hibernates/aestivates, Nocturnal
Immature Phenology: Crepuscular, Diurnal, Hibernates/aestivates, Nocturnal
Phenology Comments: Diurnal in spring and fall, nocturnal in summer (Behler and King 1979). Active late April to October in north, presumably longer in south.
Length: 257 centimeters
Economic Attributes Not yet assessed
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Management Summary Not yet assessed
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Population/Occurrence Delineation
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Group Name: Medium And Large Colubrid Snakes

Use Class: Not applicable
Minimum Criteria for an Occurrence: Occurrences are based on evidence of historical presence, or current and likely recurring presence, at a given location. Such evidence minimally includes collection or reliable observation and documentation of one or more individuals (including eggs) in or near appropriate habitat where the species is presumed to be established and breeding.
Separation Barriers: Busy highway or highway with obstructions such that snakes rarely if ever cross successfully; major river, lake, pond, or deep marsh (this barrier pertains only to upland species and does not apply to aquatic or wetland snakes); densely urbanized area dominated by buildings and pavement.
Separation Distance for Unsuitable Habitat: 1 km
Separation Distance for Suitable Habitat: 10 km
Separation Justification: Available information on movements of colubrid snakes is limited to a small minority of species. These data indicate that nearly all species have home ranges smaller or much smaller than 25 ha (e.g., less than 3 ha, Pituophis catenifer in California, Rodriguez-Robles 2003), with some up to about 75 ha (Heterodon platirhinos, average 50 ha, Plummer and Mills 2000), and the largest up to 225 ha in the biggest colubrids (Drymarchon, summer mean 50-100 ha, USFWS 1998).

Radiotelemetry data for Pantherophis indicate that residents of hibernacula that are 1-2 km apart (with suitable intervening habitat) probably interbreed (Prior et al. 1997, Blouin-Demers and Weatherhead 2002). However, "evidence of genetic structure even over short distances (e.g., 2-20 km) implies that gene flow among rat snake populations can be easily disrupted" (Prior et al. 1997). Loughheed et al. (1999) found evidence of substantial genetic exchange among local hibernacula (< 6 km apart), but gene flow over distances of 10s of km appears to be substantially less. Based on extensive radio-tracking data, Blouin-Demers and Weatherhead (2002) found that home range size of Pantherophis averaged 18.5 ha and ranged up to 93 ha; based on the most mobile individuals, Pantherophis from hibernacula up to 8 km apart can come together for mating. Pantherophis and probably other colubrids exhibit high fidelity to hibernacula and shift even to nearby sites only rarely (Prior et al. 2001).

Many of the several studies that report small home ranges for colubrids did not employ methods (e.g., radio telemetry) suitable for detecting full annual or multi-annual home range size, dispersal, or other long-distance movements, so these may have yielded underestimates of home ranges or activity areas.

At least some colubrids, including medium-sized species such as garter snakes, not uncommonly move between areas up to a few kilometers apart, and several species make extensive movements of up to several kilometers, so separation distances of 1-2 km for suitable habitat are too small for medium-sized and large colubrids.

A separation distance of 10 km for suitable habitat was selected as most appropriate for snakes assigned to this Specs Group because it seems generally unlikely that two locations separated by less than 10 km of suitable habitat would represent distinct occurrences.

For the purposes of these occurrence specifications, upland habitat is regarded as unsuitable habitat for aquatic and wetland snakes. For upland snakes, shallow or patchy wetlands are treated as unsuitable habitat whereas large deepwater habitats (subjective determination) are barriers.

Inferred Minimum Extent of Habitat Use (when actual extent is unknown): .5 km
Date: 12Feb2013
Author: Hammerson, G.
Notes: Separation distance for suitable habitat was changed from 5 km to 10 km based on comments from Dale Jackson (12 Feb 2013).
Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 14Apr2016
NatureServe Conservation Status Factors Author: Hammerson, G.
Element Ecology & Life History Edition Date: 14Apr2016
Element Ecology & Life History Author(s): Hammerson, G.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

References
Help
  • Behler, J. L., and F. W. King. 1979. The Audubon Society field guide to North American reptiles and amphibians. Alfred A. Knopf, New York. 719 pp.

  • Burbrink, F. T. 2001. Systematics of the eastern ratsnake complex (Elaphe obsoleta). Herpetological Monographs 15:1-53.

  • Burbrink, F. T., B. I. Crother and R. Lawson. 2007. The destabilization of North American Snake Taxonomy. Herpetological Review 38:273-278.

  • Burbrink, F. T., R. Lawson, and J. B. Slowinski. 2000. Mitochondrial DNA phylogeography of the North American rat snake (Elaphe obsoleta): a critique of the subspecies concept. Evolution 54:2107-2114.

  • Crother, B. I. (editor). 2008. Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. Sixth edition. Society for the Study of Amphibians and Reptiles Herpetological Circular 37:1-84.

  • Crother, B. I. (editor). 2008. Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. Sixth edition. Society for the Study of Amphibians and Reptiles Herpetological Circular 37:1-84. Online with updates at: http://www.ssarherps.org/pages/comm_names/Index.php

  • Crother, B. I. (editor). 2012. Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. 7th edition. SSAR Herpetological Circular 39:1-92.

  • DEGRAFF, R.M. AND D.D.RUDIS. 1983. AMPHIBIANS AND REPTILES OF NEW ENGLAND. HABITATS AND NATURAL HISTORY. UNIVERSITY OF MASSACHUSETTS PRESS. 83PP.

  • DeGraaf, R. M., and D. D. Rudis. 1983a. Amphibians and reptiles of New England. Habitats and natural history. Univ. Massachusetts Press. vii + 83 pp.

  • Fitch, H. S. 1970. Reproductive cycles of lizards and snakes. Univ. Kansas Museum Natural History Miscellaneous Publication 52:1-247.

  • Hulse, A. C., C. J. McCoy, and E. Censky. 2001. Amphibians and reptiles of Pennsylvania and the Northeast. Comstock Publishing Associates, Cornell University Press, Ithaca. 419 pp.

  • Kilpatrick, C.W. and M.A. Romano. 1982. Elaphe obsoleta obsoleta (Black Rat Snake). Herpetological Review 13(1):25.

  • Klemens, M. W. 1993. Amphibians and reptiles of Connecticut and adjacent regions. State Geological and Natural History Survey of Connecticut, Bulletin 112. xii + 318 pp.

  • MCCOY CJ 1982 AMPHIBIANS AND REPTILES IN PENNSYLVANIA: CHECKLIST, BIBLIOGRAPHY, AND ATLAS OF DISTRIBUTION. SP PUB CARNEGIE MUS NAT HIST, NO 6 PG 1-91,74MAPS

  • Mirarchi, R.E., editor. 2004. Alabama Wildlife. Volume 1. A checklist of vertebrates and selected invertebrates: aquatic mollusks, fishes, amphibians, reptiles, birds, and mammals. The University of Alabama Press, Tuscaloosa, Alabama. 209 pages.

  • Mount, R. H. 1975. The reptiles and amphibians of Alabama. Auburn University Agricultural Experiment Station, Auburn, Alabama. vii + 347 pages.

  • 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.

  • Utiger, U., N. Helfenberger, B. SchC. 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.

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