Drymarchon couperi - (Holbrook, 1842)
Eastern Indigo Snake
Other English Common Names: eastern indigo snake
Synonym(s): Drymarchon corais couperi (Holbrook, 1842)
Taxonomic Status: Accepted
Related ITIS Name(s): Drymarchon couperi (Holbrook, 1842) (TSN 683031)
Unique Identifier: ELEMENT_GLOBAL.2.102208
Element Code: ARADB11020
Informal Taxonomy: Animals, Vertebrates - Reptiles - Snakes
 
Kingdom Phylum Class Order Family Genus
Animalia Craniata Reptilia Squamata Colubridae Drymarchon
Genus Size: B - Very small genus (2-5 species)
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Concept Reference
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Concept Reference: Crother, B. I., J. Boundy, J. A. Campbell, K. de Queiroz, D. R. Frost, R. Highton, J. B. Iverson, P. A. Meylan, T. W. Reeder, M. E. Seidel, J. W. Sites, Jr., T. W. Taggart, S. G. Tilley, and D. B. Wake. 2000 [2001]. Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. Society for the Study of Amphibians and Reptiles, Herpetological Circular No. 29. 82 pp.
Concept Reference Code: B00CRO01NAUS
Name Used in Concept Reference: Drymarchon couperi
Taxonomic Comments: Krysko et al. (2016) proposed splitting Drymarchon couperi into a ?Gulf? species (D. kolpobasileus) and ?Atlantic? species (D. couperi) based on the General Lineage Concept of Species. This database is deferring adoption of this change pending review and acceptance by the scientific community.
Conservation Status
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NatureServe Status

Global Status: G3
Global Status Last Reviewed: 24Feb2014
Global Status Last Changed: 19Dec2002
Rounded Global Status: G3 - Vulnerable
Reasons: Historical range encompassed Coastal Plain of the southeastern United States; range and abundance have been significantly reduced, and habitat destruction still poses a threat; may be locally abundant in parts of Florida, but as a top carnivore it probably exists in low population densities; many occurrences may be too small for long-term viability.
Nation: United States
National Status: N3 (19Dec2002)

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 (S1), Florida (S3), Georgia (S2), Mississippi (SX), South Carolina (SNR)

Other Statuses

U.S. Endangered Species Act (USESA): LT: Listed threatened (31Jan1978)
Comments on USESA: Listed Threatened as Drymarchon corais couperi.
U.S. Fish & Wildlife Service Lead Region: R4 - Southeast
IUCN Red List Category: LC - Least concern

NatureServe Global Conservation Status Factors

Range Extent: 20,000-2,500,000 square km (about 8000-1,000,000 square miles)
Range Extent Comments: Historical range extended throughout the lower Coastal Plain of the southeastern United States, from southern South Carolina through Georgia and Florida to the Florida Keys, and west to southern Alabama and perhaps southeastern Mississippi. Current range includes southern Georgia (most common in the southeast; see Diemer and Speake 1983) and Florida (widely distributed througout the state, south to the Keys, though perhaps very localized in the panhandle; Moler 1985, 1992; see also Ballard 1992). The species is apparently very rare or extirpated in Alabama, Mississippi, and South Carolina. Recent reintroductions have been made in Florida, Alabama, Georgia, South Carolina, and Mississippi. One reintroduced population may be thriving in Covington County, Alabama.

Area of Occupancy: >12,500 4-km2 grid cells
Area of Occupancy Comments:  

Number of Occurrences: 81 - 300
Number of Occurrences Comments: This species is represented by many occurrences or subpopulations, but many of these may not represent populations with good viability. This species is extant in many sites in southeastern Georgia; Diemer and Speake (1983) mapped well over 100 locations in perhaps several dozen counties. In Florida, the snake is known from about 400 locations, though most records represent single specimens.

Population Size: 10,000 - 100,000 individuals
Population Size Comments: Total adult population size is unknown but likely exceeds 10,000 (conservatively assuming a density of at least 1 adult per square kilometer in an area of occupancy of at least 20,000 square kilometers).

Overall Threat Impact: High
Overall Threat Impact Comments: Decline is attributed to loss of mature longleaf pine habitat (e.g., conversion to slash and sand pine plantation, urbanization, citrus, mining, etc.), commercial collecting for pet trade (now illegal and has declined), and former widespread gassing of tortoise burrows (to collect rattlesnakes) (USFWS 1998). In northern Florida and adjacent southern Alabama and Georgia, important refugia have been lost with the decline in the gopher tortoise population (fewer burrows available) and the removal of stumps by the resinous wood industry; elsewhere, habitat fragmentation is a problem (Moler 1992).

Short-term Trend: Decline of <30% to relatively stable
Short-term Trend Comments: USFWS (1990) categorized the status as "declining." Based on current rates of habitat destruction and degradation, USFWS (1998) surmised that the range-wide population is declining, although the rate of decline is uncertain.

Long-term Trend: Decline of <50% to increase of <25%
Long-term Trend Comments: Number of occurrences and range have been reduced significantly in the past 40 years; the species underwent a population decline in the 1960s and 1970s.

Intrinsic Vulnerability: Moderately vulnerable

Other NatureServe Conservation Status Information

Inventory Needs: Determine population status, distribution. Identify for acquisition lands adjacent to MAs known to support species. Assure that both wetland and upland communities are protected within same MAs.

Protection Needs: Protection needs include the following:Strict enforcement of anti-collection laws. Ban gassing (and enforce prohibition) of holes and tortoise burrows in all states. Protect large tracts of habitat, especially sandhills and adjacent wetlands.

Distribution
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Global Range: (20,000-2,500,000 square km (about 8000-1,000,000 square miles)) Historical range extended throughout the lower Coastal Plain of the southeastern United States, from southern South Carolina through Georgia and Florida to the Florida Keys, and west to southern Alabama and perhaps southeastern Mississippi. Current range includes southern Georgia (most common in the southeast; see Diemer and Speake 1983) and Florida (widely distributed througout the state, south to the Keys, though perhaps very localized in the panhandle; Moler 1985, 1992; see also Ballard 1992). The species is apparently very rare or extirpated in Alabama, Mississippi, and South Carolina. Recent reintroductions have been made in Florida, Alabama, Georgia, South Carolina, and Mississippi. One reintroduced population may be thriving in Covington County, Alabama.

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, FL, GA, MSextirpated, SC

Range Map
Note: Range depicted for New World only. The scale of the maps may cause narrow coastal ranges or ranges on small islands not to appear. Not all vagrant or small disjunct occurrences are depicted. For migratory birds, some individuals occur outside of the passage migrant range depicted.

Range Map Compilers: NatureServe, 2005


U.S. Distribution by County Help
State County Name (FIPS Code)
AL Baldwin (01003), Mobile (01097)*
FL Alachua (12001), Baker (12003), Bay (12005)*, Bradford (12007), Brevard (12009), Calhoun (12013)*, Charlotte (12015), Citrus (12017), Clay (12019), Collier (12021), Columbia (12023), DeSoto (12027), Dixie (12029), Duval (12031), Escambia (12033)*, Flagler (12035), Franklin (12037), Gadsden (12039)*, Gilchrist (12041), Glades (12043), Hamilton (12047), Hardee (12049), Hendry (12051), Hernando (12053), Highlands (12055), Hillsborough (12057), Holmes (12059), Indian River (12061), Jackson (12063)*, Jefferson (12065), Lafayette (12067), Lake (12069), Lee (12071), Leon (12073)*, Levy (12075), Liberty (12077), Madison (12079), Manatee (12081), Marion (12083), Martin (12085), Miami-Dade (12086), Monroe (12087), Nassau (12089), Okaloosa (12091), Okeechobee (12093), Orange (12095), Osceola (12097), Palm Beach (12099), Pasco (12101), Pinellas (12103), Polk (12105), Putnam (12107), Santa Rosa (12113)*, Sarasota (12115), Seminole (12117), St. Johns (12109), St. Lucie (12111)*, Sumter (12119), Suwannee (12121), Taylor (12123), Volusia (12127), Wakulla (12129), Walton (12131), Washington (12133)*
GA Appling (13001), Atkinson (13003), Bacon (13005), Ben Hill (13017), Berrien (13019), Brantley (13025), Bryan (13029), Bulloch (13031), Camden (13039), Candler (13043), Charlton (13049), Clinch (13065), Coffee (13069), Cook (13075), Decatur (13087), Dodge (13091), Echols (13101), Effingham (13103)*, Emanuel (13107), Evans (13109), Glynn (13127)*, Irwin (13155), Jeff Davis (13161), Lanier (13173), Laurens (13175), Liberty (13179), Long (13183), Lowndes (13185), Mcintosh (13191), Pierce (13229), Randolph (13243), Seminole (13253), Tattnall (13267), Telfair (13271), Tift (13277), Toombs (13279), Turner (13287), Ware (13299), Wayne (13305), Wheeler (13309), Wilcox (13315)*
MS Forrest (28035)*, Hancock (28045)*, Harrison (28047)*, Jones (28067)*, Perry (28111)*, Wayne (28153)*
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
03 Lower Ogeechee (03060202)+, Canoochee (03060203)+, Ogeechee Coastal (03060204)+, Lower Ocmulgee (03070104)+, Little Ocmulgee (03070105)+, Altamaha (03070106)+, Ohoopee (03070107)+, Satilla (03070201)+, Little Satilla (03070202)+, Cumberland-St. Simons (03070203)+, St. Marys (03070204)+, Nassau (03070205)+, Upper St. Johns (03080101)+, Oklawaha (03080102)+, Lower St. Johns (03080103)+, Daytona - St. Augustine (03080201)+, Cape Canaveral (03080202)+, Vero Beach (03080203)+, Kissimmee (03090101)+, Northern Okeechobee Inflow (03090102)+, Western Okeechobee Inflow (03090103)+, Lake Okeechobee (03090201)+, Everglades (03090202)+, Florida Bay-Florida Keys (03090203)+, Big Cypress Swamp (03090204)+, Caloosahatchee (03090205)+, Florida Southeast Coast (03090206)+, Peace (03100101)+, Myakka (03100102)+, Charlotte Harbor (03100103)+, Sarasota Bay (03100201)+, Manatee (03100202)+, Little Manatee (03100203)+*, Alafia (03100204)+, Hillsborough (03100205)+, Tampa Bay (03100206)+, Crystal-Pithlachascotee (03100207)+, Withlacoochee (03100208)+, Waccasassa (03110101)+, Econfina-Steinhatchee (03110102)+, Aucilla (03110103)+, Upper Suwannee (03110201)+, Alapaha (03110202)+, withlacoochee (03110203)+, Little (03110204)+, Lower Suwannee (03110205)+, Santa Fe (03110206)+, Apalachee Bay-St. Marks (03120001)+, Lower Ochlockonee (03120003)+, Lower Flint (03130008)+, Ichawaynochaway (03130009)+, Spring (03130010)+, Apalachicola (03130011)+, Chipola (03130012)+*, New (03130013)+, Apalachicola Bay (03130014)+, St. Andrew-St. Joseph Bays (03140101)+*, Choctawhatchee Bay (03140102)+, Yellow (03140103)+, Blackwater (03140104)+*, Pensacola Bay (03140105)+*, Perdido (03140106)+*, Perdido Bay (03140107)+, Lower Choctawhatchee (03140203)+, Escambia (03140305)+*, Upper Leaf (03170004)+*, Lower Leaf (03170005)+*, Pascagoula (03170006)+*, Black (03170007)+*, Escatawpa (03170008)+*, Mississippi Coastal (03170009)+*, Lower Pearl. Mississippi (03180004)+*
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: Eastern indigo snake, Colubridae.
General Description: The longest of North American snakes; heavy-bodied and shiny blue-black overall; chin, throat, and sides of head variably suffused with cream, orange, or red; scales unkeeled (males may have partial keel on scales of the middorsal 3-5 scale rows); anal undivided; 17 scale rows at mid-body; 1 preocular; third from last upper labial distinctly narrowed at the top; adult total length usually 152-213 cm (to 263 cm), about 43-61 cm at hatching (Conant and Collins, Smith and Brodie 1982).
Diagnostic Characteristics: Differs from Drymarchon corais erebennus as follows: lacks prominent black lines extending downward from the eye; body does not tend to be brownish anteriorly; two labials meet above the third from last one; and there are usually 15 dorsal scale rows at the rear end of the body (rather than 14) (Conant and Collins 1991).
Reproduction Comments: Copulation occurs primarily in fall and winter. Eggs are laid in May-June (also reportedly as early as April). Clutch size usually is 5-10. Hatchlings appear from late July through October. Females can lay fertile eggs after several years of isolation (Behler and King 1979, Moler 1992).
Ecology Comments: Ranges widely in warmer months, with home range 50-100 ha or more (up to 224 ha in males, USFWS 1998); in winter, usually stays fairly close to a deep shelter, with home range usually less than 10 ha (Moler 1992).
Habitat Type: Terrestrial
Non-Migrant: Y
Locally Migrant: Y
Long Distance Migrant: N
Mobility and Migration Comments: May move seasonally between upland wintering sites and wetter lowland feeding areas (Moler 1992).
Palustrine Habitat(s): Riparian
Terrestrial Habitat(s): Forest - Conifer, Forest - Hardwood, Forest - Mixed, Shrubland/chaparral, Woodland - Conifer, Woodland - Hardwood, Woodland - Mixed
Special Habitat Factors: Burrowing in or using soil, Fallen log/debris
Habitat Comments: Habitat includes sandhill regions dominated by mature longleaf pines, turkey oaks, and wiregrass; flatwoods; most types of hammocks; coastal scrub; dry glades; palmetto flats; prairie; brushy riparian and canal corridors; and wet fields (Matthews and Moseley 1990, Tennant 1997, Ernst and Ernst 2003). Occupied sites are often near wetlands and frequently are in association with gopher tortoise burrows. Pineland habitat is maintained by periodic fires. Viable populations of this species require relatively large tracts of suitable habitat. Refuges include tortoise burrows, stump holes, land crab burrows, armadillo burrows, or similar sites. Eggs may be laid in gopher (Geomys) burrows (Ashton and Ashton 1981). See USFWS (1998) for further information.
Adult Food Habits: Carnivore
Immature Food Habits: Carnivore
Food Comments: Eats small mammals, birds, frogs, snakes, lizards, and other vertebrates of appropriate size. Rossi (1994, Herpetol. Rev. 25:123-124) reported a juvenile that had eaten a large slug. Active forager; often searches along edges of wetlands (Moler 1992).
Adult Phenology: Diurnal
Immature Phenology: Diurnal
Phenology Comments: Primarily diurnal, but partly nocturnal in some areas (McCranie 1980). Inactive for a week or two prior to shedding (Moler 1992).
Length: 213 centimeters
Economic Attributes Not yet assessed
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Management Summary
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Restoration Potential: Apparently reproduces well in captivity; reintroductions using captive-bred animals might be feasible once habitat is protected and properly managed. As of 1990, the Alabama Cooperative Wildlife Research Unit had released captive-reared individuals in Florida, Alabama, Georgia, and Mississippi; some of the releases have been "successful" (USFWS 1990).
Preserve Selection & Design Considerations: Moler (1992) emphasized the need for protection of large tracts of suitable habitat (generally at least 1000 ha).
Management Requirements: Beneficial management techniques include mechanical thinning and controlled burning to prevent overgrowth of pine by hardwoods, prohibition of clear-cutting, and public education to discourage killing and collecting. In xeric habitats, will benefit from efforts to rebuild gopher tortoise populations (Moler 1992). Existing prohibitions against the gassing of tortoise burrows should be strongly enforced (Moler 1992). Unnecessary roads in managed areas should be closed.

See USFWS (1998) for specific information on recovery and management in Florida.

Monitoring Requirements: Monitor managed areas for illegal collection. Monitor highway mortality and crossings to determine need for underpasses.
Management Research Needs: Determine habitat requirements, limiting factors, movements and home range in different areas and habitats, population densities, and critical size of habitat needed to assure population viability.
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: 06Apr2011
NatureServe Conservation Status Factors Author: Jackson, D. R., and G. Hammerson
Element Ecology & Life History Edition Date: 06Sep2005
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
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  • Alabama Department of Conservation and Natural Resources, Division of Wildlife and Freshwater Fisheries. 2005. Conserving Alabama's wildlife: a comprehensive strategy. Alabama Department of Conservation and Natural Resources, Division of Wildlife and Freshwater Fisheries. Montgomery, Alabama. 303 pages. [Available online at http://www.dcnr.state.al.us/research-mgmt/cwcs/outline.cfm ]

  • Ashton, R. E., Jr., and P. S. Ashton. 1981. Handbook of reptiles and amphibians of Florida. Part One: The Snakes. Windward Publishing Company, Miami, Florida. 176 pp.

  • Ballard, S. R. 1992. Geographic distribution: DRYMARCHON CORAIS COUPERI. Herpetological Review 23:26-27.

  • Bauder, J. M., D. R. Breininger, M. R. Bolt, M. L. Legare, C. L. Jenkins, B. B. Rothermel, and K. McGarigal.  2016.  Seasonal variation in eastern indigo snake (Drymarchon couperi) movement patterns and space use in peninsular Florida at multiple temporal scales. Herpetologica 72:214-226.

  • 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.

  • Carr, A., and C. J. Goin. 1955. Guide to the reptiles, amphibians and fresh-water fishes of Florida. Univ. Florida Press, Gainesville.

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  • 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.

  • Crother, B. I., J. Boundy, J. A. Campbell, K. de Queiroz, D. R. Frost, R. Highton, J. B. Iverson, P. A. Meylan, T. W. Reeder, M. E. Seidel, J. W. Sites, Jr., T. W. Taggart, S. G. Tilley, and D. B. Wake. 2000 [2001]. Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. Society for the Study of Amphibians and Reptiles, Herpetological Circular No. 29. 82 pp.

  • Diemer, J. E., and D. W. Speake. 1983. The distribution of the eastern indigo snake, DRYMARCHON CORAIS COUPERI, in Georgia. J. Herpetology 17:256-264.

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  • Hart, B. 2002. Status survey of the eastern indigo snake (Drymarchon couperi Holbrook), black pine snake (Pituophis melanoleucus lodingi Blanchard), and southern hognose snake (Heterodon simus Linnaeus) in Alabama. Unpublished report to The Alabama Department of Conservation and Natural Resources, Division of Wildlife and Freshwater Fisheries. Montgomery, Alabama. Alabama Natural Heritage Program, Montgomery, Alabama. 49 pages.

  • Krysko, K. L., K. M. Enge, and P. E. Moler. 2011. Atlas of amphibians and reptiles in Florida. Final report to Florida Fish and Wildlife Conservation Commission, Tallahassee, Florida. Submitted 15 December 2011.

  • Krysko, K. L., L. P. Nuñez, C. A. Lippi, D. J. Smith, and M. C. Granatosky.  2016.  Pliocene?Pleistocene lineage diversifications in the eastern indigo snake (Drymarchon couperi) in the southeastern United States.  Molecular Phylogenetics and Evolution 98:111?122.

  • Krysko, K. L., M. C. Granatosky, L. P. Nunez, and D. J. Smith.  A cryptic new species of Indigo Snake (genus Drymarchon) from the Florida Platform of the United States.  Zootaza 4138(3):549-569.

  • Krysko, K.L., M.C. Granatosky, L.P. Nunez, and D.J. Smith. A cryptic new species of Indigo Snake (genus Drymarchon) from the Florida Platform of the United States. Zootaza 4138(3):549-569.

  • Lohoefener, R. and R. Altig. 1983. Mississippi herpetology. Mississippi State University Research Center, NSTL Station, Mississippi. 66 pp.

  • Matthews, J.R. and C.J. Moseley (eds.). 1990. The Official World Wildlife Fund Guide to Endangered Species of North America. Volume 1. Plants, Mammals. xxiii + pp 1-560 + 33 pp. appendix + 6 pp. glossary + 16 pp. index. Volume 2. Birds, Reptiles, Amphibians, Fishes, Mussels, Crustaceans, Snails, Insects, and Arachnids. xiii + pp. 561-1180. Beacham Publications, Inc., Washington, D.C.

  • McCranie, James R. 1980. Drymarchon, D. corias. Catalogue of American Amphibians and Reptiles. (267):1-4.

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  • 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.

  • Mississippi Department of Wildlife Conservation. Bureau of Fisheries and Wildlife. 1988. Public Notice No. 279.

  • Moler, P. E. 1985. Distribution of the eastern indigo snake, DRYMARCHON CORAIS COUPERI, in Florida. SSAR Herpetol. Rev. 16(2):37-38.

  • Moler, P. E. 1992. Eastern indigo snake Drymarchon corais couperi (Holbrook). Pages 181-186 in P. E. Moler, editor. Rare and endangered biota of Florida. Vol. III. Amphibians and reptiles. Univ. Press of Florida.

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

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

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