Overview

Comprehensive Description

The Eastern Indigo Snake (Drymarchon couperi) is a large shiny bluish black snake, sometimes with chin, throat, and sides of head with cream, reddish, or orange brown. It is the largest North American snake, reaching about 150 to 210 cm (record 263 cm). The scales are normally smooth, but some males, especially larger individuals, have faintly keeled scales on as many as five middorsal rows, starting at about the second quarter of the body; the anal plate is undivided. The third from last upper labial is wedge-shaped and cut off above by contact between adjacent labials. Young are like adults, but often with much more reddish on head and forward part of belly, 43 to 66 cm at hatching. (Behler 1979; Conant and Collins 1991)

The current stronghold for this threatened species is southeastern Georgia and peninsular Florida. It persists in lower numbers in Florida's panhandle, but is functionally extinct in Alabama and Mississippi. (USFWS 2008)

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Drymarchon couperi, the eastern indigo snake, is a heavy-bodied, docile, and non-venomous snake. The longest native snake in North America, it grows to lengths of 1.88 - 2.65 m (6.2 - 8.7 feet) (Ashton and Ashton 1981; King and Krysko 2000). Body color is a uniform iridescent blue-black to black color except for a patch of red to reddish-cream around the chin, throat, and cheeks.The extent and vibrancy of this patch varies with geographic location. Scales are large and smooth, with the central 3 - 5 scale rows keeled in adult males. There are 17 scale rows measured at mid-body, and the anal plate is undivided. Juveniles measure 43 - 61 cm (17 - 24 inches) at hatching, are typically black, have narrow whitish to bluish bands along the body, and are more red or cream colored around the head (USFWS 1999; Conanat and Collins 1991).
  • Ashton R. and P. Ashton. 1981. Handbook of Reptiles and Amphibians of Florida. Windward Publishing, Inc. Miami, FL.
  • Bogert, C. and R. Cowles. 1947. Results of the Archbold expeditions.No. 58. Moisture loss in relation to habitat selection in some Floridian reptiles. American Museum Noviciates 1358:1 - 55.
  • Carson, H. 1945. Delayed fertilization in a captive indigo snake with a note of feeding and shedding. Copeia 1945(4):222-224.
  • Conant R. and J.T. Collins. 1991. A Field Guide to Reptiles and Amphibians.Houghton Mifflin Company, Boston, MA.
  • Hallam, C.O., K. Wheaton, and R. Fischer. 1998. Species profile: Eastern indigo snake (Drymarchon corais couperi) on military installations in the Southeastern United States. Technical report SERDP-98-2, March 1998. Strategic Environmental Research and Development Program, U.S. Army Corps. of Engineers, Waterways Experiment Station, Vicksburg, MS.
  • King, F.W. and K.L. Krysko. 2000. Online Guide to the Snakes of Florida. Florida Museum of Natural History, University of Florida, Gainesville, FL. 266 pp. Available at http://www.flmnh.ufl.edu/natsci/herpetology/fl-guide/onlineguide.htm.
  • Lawler, H.E. 1977. The status of Drymarchon corais couperi (Holbrook), the eastern indigo snake, in the southeastern USA. Herpetological Review 8(3):76-79.
  • Lazell, J. 1989. Wildlife of the Florida Keys: a Natural History. Island Press. Washington, DC.
  • Moler, P.E. 1985a. Home range and seasonal activity in the eastern indigo snake, Drymarchon corais couperi, in northern Florida. Final performance report, Study E-1-06, III-A-5. Florida Game and Fresh Water Fish Commission; Tallahassee, FL.
  • Moler, P.E. 1985b. Distribution of the eastern indigo snake, Drymarchon corais couperi, in Florida. Herpetological Review 16(2):37-38.
  • Moler, P.E. 1992. Eastern indigo snake. Pps 181 - 196 in: P.E. Moler (ed). Rare and Endangered Biota of Florida, Volume III, Amphibians and Reptiles. University Press of Florida, Gainesville, FL.
  • Shaw, C.E. 1959. Longevity of snakes in the U.S. as of January 1, 1959. Copeia 1959(4):336-337.
  • Speake, D.W. 1993. Indigo snake recovery plan revision. Final report to the U.S.Fish and Wildlife Service; Jacksonville, Florida.
  • Speake, D.W., and R.H. Mount. 1973. Some possible ecological effects of "rattlesnake roundups" in the southeastern coastal plain. Proceedings of the annual conference of the Southeastern Association of Fish and Wildlife Agencies 27:267-277.
  • Speake, D.W., J.A. McGlincy, and T.R. Colvin. 1978. Ecology and managementof the eastern indigo snake in Georgia: A progress report. Pages 64-73 in: R.R. Odum and L. Landers, (eds.), Proceedings of rare and endangered wildlife symposium, Georgia Department of Natural Resources, Game and Fish Division, Technical Bulletin WL 4.
  • Speake, D.W., and J.A. McGlincy, 1981. Response of indigo snakes to gassing of their dens. Proceedings of the annual conference of the Southeastern Association of Fish and Wildlife Agencies. 35:135-138.
  • Speake, D.W., D. McGlincy, and C. Smith. 1987. Captive breeding andexperimental reintroduction of the eastern indigo snake. Pps. 84 - 90 in:R.R. Odom, K.A. Riddleberger, and J.C. Ozier (eds.), Proceedings. 3rd Southeastern Nongame and Endangered Wildlife Symposium, Georgia Department of Natural Resources, Game and Fish Division.
  • Steiner, T.M., O.L. Bass, Jr., and J.A. Kushlan. 1983. Status of the eastern indigo snake in southern Florida National Parks and vicinity. South FloridaResearch Center Report SFRC-83/01, Everglades National Park; Homestead, Florida.U.S. Fish and Wildlife Service USFWS). 1982. Eastern indigo snake recovery plan. U.S. Fish and Wildlife Service, Atlanta, Georgia.U.S. Fish and Wildlife Service (USFWS). 1999. South Florida multi-speciesrecovery plan. Atlanta, GA. 2,172 pp.
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Source: Indian River Lagoon Species Inventory

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Distribution

endemic to a single nation

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National Distribution

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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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.

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Range Description

This species is endemic to the southeastern United States. Its 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. Its current range includes southern Georgia (most common in the southeast; see Diemer and Speake 1983) and Florida (widely distributed throughout 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.
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Geographic Range

Eastern indigo snakes are most common in Florida and the southern regions of Georgia, although they used to occur throughout much of Alabama, Texas, and South Carolina, as well. Populations in those areas have largely been lost due to habitat destruction, poaching, and killing of these snakes.

Biogeographic Regions: nearctic (Native )

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Continent: North-America
Distribution: USA (Georgia, Florida, west to SE Mississippi)  Largest North-American snake with a total length up to 260 cm (males usually 210-230 cm, females 160-180 cm).
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The historic range of Drymarchon couperi included the coastal plains of Georgia, Alabama, Mississippi, and possibly Southern South Carolina. Currently indigo snakes primarily range throughout Florida, including the Florida Keys, and into southern Georgia (Lazell 1989; Lawler 1977). Drymarchon couperi occurs throughout the India River Lagoon.
  • Ashton R. and P. Ashton. 1981. Handbook of Reptiles and Amphibians of Florida. Windward Publishing, Inc. Miami, FL.
  • Bogert, C. and R. Cowles. 1947. Results of the Archbold expeditions.No. 58. Moisture loss in relation to habitat selection in some Floridian reptiles. American Museum Noviciates 1358:1 - 55.
  • Carson, H. 1945. Delayed fertilization in a captive indigo snake with a note of feeding and shedding. Copeia 1945(4):222-224.
  • Conant R. and J.T. Collins. 1991. A Field Guide to Reptiles and Amphibians.Houghton Mifflin Company, Boston, MA.
  • Hallam, C.O., K. Wheaton, and R. Fischer. 1998. Species profile: Eastern indigo snake (Drymarchon corais couperi) on military installations in the Southeastern United States. Technical report SERDP-98-2, March 1998. Strategic Environmental Research and Development Program, U.S. Army Corps. of Engineers, Waterways Experiment Station, Vicksburg, MS.
  • King, F.W. and K.L. Krysko. 2000. Online Guide to the Snakes of Florida. Florida Museum of Natural History, University of Florida, Gainesville, FL. 266 pp. Available at http://www.flmnh.ufl.edu/natsci/herpetology/fl-guide/onlineguide.htm.
  • Lawler, H.E. 1977. The status of Drymarchon corais couperi (Holbrook), the eastern indigo snake, in the southeastern USA. Herpetological Review 8(3):76-79.
  • Lazell, J. 1989. Wildlife of the Florida Keys: a Natural History. Island Press. Washington, DC.
  • Moler, P.E. 1985a. Home range and seasonal activity in the eastern indigo snake, Drymarchon corais couperi, in northern Florida. Final performance report, Study E-1-06, III-A-5. Florida Game and Fresh Water Fish Commission; Tallahassee, FL.
  • Moler, P.E. 1985b. Distribution of the eastern indigo snake, Drymarchon corais couperi, in Florida. Herpetological Review 16(2):37-38.
  • Moler, P.E. 1992. Eastern indigo snake. Pps 181 - 196 in: P.E. Moler (ed). Rare and Endangered Biota of Florida, Volume III, Amphibians and Reptiles. University Press of Florida, Gainesville, FL.
  • Shaw, C.E. 1959. Longevity of snakes in the U.S. as of January 1, 1959. Copeia 1959(4):336-337.
  • Speake, D.W. 1993. Indigo snake recovery plan revision. Final report to the U.S.Fish and Wildlife Service; Jacksonville, Florida.
  • Speake, D.W., and R.H. Mount. 1973. Some possible ecological effects of "rattlesnake roundups" in the southeastern coastal plain. Proceedings of the annual conference of the Southeastern Association of Fish and Wildlife Agencies 27:267-277.
  • Speake, D.W., J.A. McGlincy, and T.R. Colvin. 1978. Ecology and managementof the eastern indigo snake in Georgia: A progress report. Pages 64-73 in: R.R. Odum and L. Landers, (eds.), Proceedings of rare and endangered wildlife symposium, Georgia Department of Natural Resources, Game and Fish Division, Technical Bulletin WL 4.
  • Speake, D.W., and J.A. McGlincy, 1981. Response of indigo snakes to gassing of their dens. Proceedings of the annual conference of the Southeastern Association of Fish and Wildlife Agencies. 35:135-138.
  • Speake, D.W., D. McGlincy, and C. Smith. 1987. Captive breeding andexperimental reintroduction of the eastern indigo snake. Pps. 84 - 90 in:R.R. Odom, K.A. Riddleberger, and J.C. Ozier (eds.), Proceedings. 3rd Southeastern Nongame and Endangered Wildlife Symposium, Georgia Department of Natural Resources, Game and Fish Division.
  • Steiner, T.M., O.L. Bass, Jr., and J.A. Kushlan. 1983. Status of the eastern indigo snake in southern Florida National Parks and vicinity. South FloridaResearch Center Report SFRC-83/01, Everglades National Park; Homestead, Florida.U.S. Fish and Wildlife Service USFWS). 1982. Eastern indigo snake recovery plan. U.S. Fish and Wildlife Service, Atlanta, Georgia.U.S. Fish and Wildlife Service (USFWS). 1999. South Florida multi-speciesrecovery plan. Atlanta, GA. 2,172 pp.
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Source: Indian River Lagoon Species Inventory

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The Eastern Indigo Snake (Drymarchon couperi) is found in the eastern United States from southeastern Georgia, peninsular Florida and the lower Keys west to southeastern Mississippi; it was apparently released outside its native range in extreme southern Mississippi by governmental agencies (Conant and Collins 1991). Historically, this species occurred throughout Florida and in the coastal plain of Georgia, Alabama, and Mississippi (USFWS 2008 and references therein).

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Physical Description

Morphology

Physical Description

Eastern indigo snakes are the largest snakes in the United States and the largest, non-venomous snakes in the southeastern United States. Eastern indigo snakes are uniformly black with the exception of a red or cream colored area on the chin, throat, and, occasionally, the cheeks. The scales are smooth and large, typically with 17 scale rows at the mid body. Adults typical reach between 157.2 and 213.36 cm long. The record, however, is 280.4 cm long. Eastern indigo snakes are sexually dimorphic, with males growing longer than females. Eastern indigo snake young are similar in appearance, with the exception of a white band around their body. These snakes are commonly confused with with racers. Racers differ from eastern indigo snakes in several aspects: racers are rarely over 121.9 cm long, they are often thinner and have a dull black coloration with white or brown throats.

Range mass: 14 to 30 g.

Average mass: 24 g.

Range length: 152.4 to 213.36 cm.

Average length: 174.7 cm.

Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry

Sexual Dimorphism: male larger

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Size

Length: 213 cm

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Eastern Indigo snakes are the longest native snakes in the U.S. and grow to lengths of 1.88 - 2.65 m (Ashton and Ashton 1981; King and Krysko 2000). Juveniles measure 43 - 61 cm (17 -24 inches) at hatching. Little information is available regarding the lifespan of wild eastern indigo snakes; however, captive snakes have been documented to live more than 25 years (Shaw 1959).
  • Ashton R. and P. Ashton. 1981. Handbook of Reptiles and Amphibians of Florida. Windward Publishing, Inc. Miami, FL.
  • Bogert, C. and R. Cowles. 1947. Results of the Archbold expeditions.No. 58. Moisture loss in relation to habitat selection in some Floridian reptiles. American Museum Noviciates 1358:1 - 55.
  • Carson, H. 1945. Delayed fertilization in a captive indigo snake with a note of feeding and shedding. Copeia 1945(4):222-224.
  • Conant R. and J.T. Collins. 1991. A Field Guide to Reptiles and Amphibians.Houghton Mifflin Company, Boston, MA.
  • Hallam, C.O., K. Wheaton, and R. Fischer. 1998. Species profile: Eastern indigo snake (Drymarchon corais couperi) on military installations in the Southeastern United States. Technical report SERDP-98-2, March 1998. Strategic Environmental Research and Development Program, U.S. Army Corps. of Engineers, Waterways Experiment Station, Vicksburg, MS.
  • King, F.W. and K.L. Krysko. 2000. Online Guide to the Snakes of Florida. Florida Museum of Natural History, University of Florida, Gainesville, FL. 266 pp. Available at http://www.flmnh.ufl.edu/natsci/herpetology/fl-guide/onlineguide.htm.
  • Lawler, H.E. 1977. The status of Drymarchon corais couperi (Holbrook), the eastern indigo snake, in the southeastern USA. Herpetological Review 8(3):76-79.
  • Lazell, J. 1989. Wildlife of the Florida Keys: a Natural History. Island Press. Washington, DC.
  • Moler, P.E. 1985a. Home range and seasonal activity in the eastern indigo snake, Drymarchon corais couperi, in northern Florida. Final performance report, Study E-1-06, III-A-5. Florida Game and Fresh Water Fish Commission; Tallahassee, FL.
  • Moler, P.E. 1985b. Distribution of the eastern indigo snake, Drymarchon corais couperi, in Florida. Herpetological Review 16(2):37-38.
  • Moler, P.E. 1992. Eastern indigo snake. Pps 181 - 196 in: P.E. Moler (ed). Rare and Endangered Biota of Florida, Volume III, Amphibians and Reptiles. University Press of Florida, Gainesville, FL.
  • Shaw, C.E. 1959. Longevity of snakes in the U.S. as of January 1, 1959. Copeia 1959(4):336-337.
  • Speake, D.W. 1993. Indigo snake recovery plan revision. Final report to the U.S.Fish and Wildlife Service; Jacksonville, Florida.
  • Speake, D.W., and R.H. Mount. 1973. Some possible ecological effects of "rattlesnake roundups" in the southeastern coastal plain. Proceedings of the annual conference of the Southeastern Association of Fish and Wildlife Agencies 27:267-277.
  • Speake, D.W., J.A. McGlincy, and T.R. Colvin. 1978. Ecology and managementof the eastern indigo snake in Georgia: A progress report. Pages 64-73 in: R.R. Odum and L. Landers, (eds.), Proceedings of rare and endangered wildlife symposium, Georgia Department of Natural Resources, Game and Fish Division, Technical Bulletin WL 4.
  • Speake, D.W., and J.A. McGlincy, 1981. Response of indigo snakes to gassing of their dens. Proceedings of the annual conference of the Southeastern Association of Fish and Wildlife Agencies. 35:135-138.
  • Speake, D.W., D. McGlincy, and C. Smith. 1987. Captive breeding andexperimental reintroduction of the eastern indigo snake. Pps. 84 - 90 in:R.R. Odom, K.A. Riddleberger, and J.C. Ozier (eds.), Proceedings. 3rd Southeastern Nongame and Endangered Wildlife Symposium, Georgia Department of Natural Resources, Game and Fish Division.
  • Steiner, T.M., O.L. Bass, Jr., and J.A. Kushlan. 1983. Status of the eastern indigo snake in southern Florida National Parks and vicinity. South FloridaResearch Center Report SFRC-83/01, Everglades National Park; Homestead, Florida.U.S. Fish and Wildlife Service USFWS). 1982. Eastern indigo snake recovery plan. U.S. Fish and Wildlife Service, Atlanta, Georgia.U.S. Fish and Wildlife Service (USFWS). 1999. South Florida multi-speciesrecovery plan. Atlanta, GA. 2,172 pp.
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Source: Indian River Lagoon Species Inventory

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Diagnostic Description

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).

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Look Alikes

Juveniles may be easily confused with southern black racers (Coluber constrictor priapus) due to the pale patches around the chin and cheeks. Black pine snakes (Pituophis melanoleucas lodingi) are similar in color and size, but lack the iridescent sheen of the indigo snake. They also retain a faint crossbanding pattern on the tail that indigo snakes lack.
  • Ashton R. and P. Ashton. 1981. Handbook of Reptiles and Amphibians of Florida. Windward Publishing, Inc. Miami, FL.
  • Bogert, C. and R. Cowles. 1947. Results of the Archbold expeditions.No. 58. Moisture loss in relation to habitat selection in some Floridian reptiles. American Museum Noviciates 1358:1 - 55.
  • Carson, H. 1945. Delayed fertilization in a captive indigo snake with a note of feeding and shedding. Copeia 1945(4):222-224.
  • Conant R. and J.T. Collins. 1991. A Field Guide to Reptiles and Amphibians.Houghton Mifflin Company, Boston, MA.
  • Hallam, C.O., K. Wheaton, and R. Fischer. 1998. Species profile: Eastern indigo snake (Drymarchon corais couperi) on military installations in the Southeastern United States. Technical report SERDP-98-2, March 1998. Strategic Environmental Research and Development Program, U.S. Army Corps. of Engineers, Waterways Experiment Station, Vicksburg, MS.
  • King, F.W. and K.L. Krysko. 2000. Online Guide to the Snakes of Florida. Florida Museum of Natural History, University of Florida, Gainesville, FL. 266 pp. Available at http://www.flmnh.ufl.edu/natsci/herpetology/fl-guide/onlineguide.htm.
  • Lawler, H.E. 1977. The status of Drymarchon corais couperi (Holbrook), the eastern indigo snake, in the southeastern USA. Herpetological Review 8(3):76-79.
  • Lazell, J. 1989. Wildlife of the Florida Keys: a Natural History. Island Press. Washington, DC.
  • Moler, P.E. 1985a. Home range and seasonal activity in the eastern indigo snake, Drymarchon corais couperi, in northern Florida. Final performance report, Study E-1-06, III-A-5. Florida Game and Fresh Water Fish Commission; Tallahassee, FL.
  • Moler, P.E. 1985b. Distribution of the eastern indigo snake, Drymarchon corais couperi, in Florida. Herpetological Review 16(2):37-38.
  • Moler, P.E. 1992. Eastern indigo snake. Pps 181 - 196 in: P.E. Moler (ed). Rare and Endangered Biota of Florida, Volume III, Amphibians and Reptiles. University Press of Florida, Gainesville, FL.
  • Shaw, C.E. 1959. Longevity of snakes in the U.S. as of January 1, 1959. Copeia 1959(4):336-337.
  • Speake, D.W. 1993. Indigo snake recovery plan revision. Final report to the U.S.Fish and Wildlife Service; Jacksonville, Florida.
  • Speake, D.W., and R.H. Mount. 1973. Some possible ecological effects of "rattlesnake roundups" in the southeastern coastal plain. Proceedings of the annual conference of the Southeastern Association of Fish and Wildlife Agencies 27:267-277.
  • Speake, D.W., J.A. McGlincy, and T.R. Colvin. 1978. Ecology and managementof the eastern indigo snake in Georgia: A progress report. Pages 64-73 in: R.R. Odum and L. Landers, (eds.), Proceedings of rare and endangered wildlife symposium, Georgia Department of Natural Resources, Game and Fish Division, Technical Bulletin WL 4.
  • Speake, D.W., and J.A. McGlincy, 1981. Response of indigo snakes to gassing of their dens. Proceedings of the annual conference of the Southeastern Association of Fish and Wildlife Agencies. 35:135-138.
  • Speake, D.W., D. McGlincy, and C. Smith. 1987. Captive breeding andexperimental reintroduction of the eastern indigo snake. Pps. 84 - 90 in:R.R. Odom, K.A. Riddleberger, and J.C. Ozier (eds.), Proceedings. 3rd Southeastern Nongame and Endangered Wildlife Symposium, Georgia Department of Natural Resources, Game and Fish Division.
  • Steiner, T.M., O.L. Bass, Jr., and J.A. Kushlan. 1983. Status of the eastern indigo snake in southern Florida National Parks and vicinity. South FloridaResearch Center Report SFRC-83/01, Everglades National Park; Homestead, Florida.U.S. Fish and Wildlife Service USFWS). 1982. Eastern indigo snake recovery plan. U.S. Fish and Wildlife Service, Atlanta, Georgia.U.S. Fish and Wildlife Service (USFWS). 1999. South Florida multi-speciesrecovery plan. Atlanta, GA. 2,172 pp.
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Lookalikes

All other plain black snakes within the range of the Eastern Indigo Snake have keeled scales, a divided anal plate, or both (Conant and Collins 1991).

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Ecology

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.

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Habitat and Ecology

Habitat and Ecology
Its 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.

Systems
  • Terrestrial
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Eastern indigo snakes can be found in a variety of environments including pine and scrubby flatwoods, high pine, dry prairie, tropical hardwood hammocks, edges of freshwater marshes, agricultural fields, coastal dunes, and human-altered habitats. These snakes thrive more in wetland environments, as opposed to xeric conditions. Often eastern indigo snakes can be found living in the same habitat as gopher tortoises. Eastern indigo snakes use gopher tortoise burrows for shelter in the xeric habitats where gopher tortoises are found. In more moist habitats, eastern indigo snakes take shelter in hollowed root channels, hollow logs, or the burrows of rodents, armadillos, or land crabs.  One study (Smith 1987) concluded that eastern indigo snakes live in different habitats throughout the year and at different stages of their lives. For example, adults and juveniles use different burrow habitats.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: desert or dune ; savanna or grassland ; forest ; scrub forest

Wetlands: marsh

Other Habitat Features: agricultural

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The Eastern Indigo Snake is found in pine woods, turkey oak, and palmetto stands near water, orange groves, and tropical hammocks (Behler 1979). It occurs mainly in large, unsettled areas (Conant and Collins 1991). Based on their work with Eastern Indigo Snakes in southeastern Georgia, Hyslop et al. (2009) suggest that availability of Gopher Tortoise (Gopherus polyphemus) burrows, which are used by the snakes as shelters, may be a limiting factor for the Eastern Indigo Snake in the northern part of its range (see also, e.g., Stevenson et al. 2003).

In a study in Georgia, Indigo Snake populations were typically associated with deep, excessively drained sandy soils on sand ridges along major coastal plain streams; winter sightings occurred almost exclusively on sandhills and in association with Gopher Tortoises (Diemer and Speake 1983).

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Migration

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

May move seasonally between upland wintering sites and wetter lowland feeding areas (Moler 1992).

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Trophic Strategy

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).

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Food Habits

Eastern indigo snakes consume a variety of food sources. They have one of the most varied diets of any snake. Eastern indigo snakes eat mammals, frogs, lizards, fish, eggs, birds, and other snakes, including venomous snakes. Eastern indigo snakes are immune to the venom of sympatric species of venomous snakes. Interestingly, they are one of the only snakes known to eat young turtles. Like other snakes, they typical eat their prey while it is still living. However there has been recorded cases of an eastern indigo snake beating prey against a nearby object to kill it. Eastern indigo snakes do not constrict their prey, they typically overpower it until the prey is exhausted to the point at which it can't escape, sometimes immobilizing the prey by pressing it to the ground. Their powerful jaws are used to grasp and pin down their prey until it can be ingested.

Animal Foods: birds; mammals; amphibians; reptiles; fish; eggs

Primary Diet: carnivore (Eats terrestrial vertebrates, Piscivore , Eats eggs)

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As they lack venom and do not constrict, eastern indigo snakes attack any vertebrate small enough to be overpowered and killed with their strong jaws. They have been observed to flush prey from cover, then give chase (Layne and Steiner 1996).They also occasionally climb trees or shrubs in search of prey. The diet includes toads, frogs, lizards, other snakes (including venomous types), turtles, turtle eggs, gopher tortoises, small alligators, birds, and rodents. Juveniles consume primarily invertebrates (USFWS 1999; Layne and Steiner 1996; Steiner et al. 1983).Activity Time: Diurnal.Habitats: Drymarchon couperi utilizes a variety of habitat types and shows some preference for open, undeveloped uplands. Typical habitats include pine flatwoods, scrubby flatwoods, high pine, dry prairie, tropical hardwood hammocks, marshes, coastal dunes and scrub, and mangrove forests (Steiner et al. 1983; USFWS 1999). In Georgia and Northern Florida, indigo snakes can be temperature-restricted to sandhill areas where gopher tortoises burrows are available to shelter in when winter temperatures drop below approximately 10 °C. In peninsular Florida, where winter temperatures are not typically challenging, indigo snakes are found in all terrestrial habitats that are not densely developed. Along the coast, indigo snakes frequently use sandy ridges and hammock areas (Moler 1985b).Drymarchon couperi move between habitats frequently, especially during the summer and fall (Moler 1985a), and thus have extensive home ranges. Speake et al. (1978) reported home range sizes for indigo snakes in Georgia averaging 4.8 ha in winter (December - April) and 42.9 ha in late spring and summer (May - July). Moler (1985a) reported that adult males utilize larger areas then either females or juveniles, perhaps encompassing 224 ha. Layne and Steiner (1996) reported male home range size as averaging approximately 74 ha (with a maximum of 199.2 ha), while females averaged approximately 19 ha (with a maximum of 48.6 ha).
  • Ashton R. and P. Ashton. 1981. Handbook of Reptiles and Amphibians of Florida. Windward Publishing, Inc. Miami, FL.
  • Bogert, C. and R. Cowles. 1947. Results of the Archbold expeditions.No. 58. Moisture loss in relation to habitat selection in some Floridian reptiles. American Museum Noviciates 1358:1 - 55.
  • Carson, H. 1945. Delayed fertilization in a captive indigo snake with a note of feeding and shedding. Copeia 1945(4):222-224.
  • Conant R. and J.T. Collins. 1991. A Field Guide to Reptiles and Amphibians.Houghton Mifflin Company, Boston, MA.
  • Hallam, C.O., K. Wheaton, and R. Fischer. 1998. Species profile: Eastern indigo snake (Drymarchon corais couperi) on military installations in the Southeastern United States. Technical report SERDP-98-2, March 1998. Strategic Environmental Research and Development Program, U.S. Army Corps. of Engineers, Waterways Experiment Station, Vicksburg, MS.
  • King, F.W. and K.L. Krysko. 2000. Online Guide to the Snakes of Florida. Florida Museum of Natural History, University of Florida, Gainesville, FL. 266 pp. Available at http://www.flmnh.ufl.edu/natsci/herpetology/fl-guide/onlineguide.htm.
  • Lawler, H.E. 1977. The status of Drymarchon corais couperi (Holbrook), the eastern indigo snake, in the southeastern USA. Herpetological Review 8(3):76-79.
  • Lazell, J. 1989. Wildlife of the Florida Keys: a Natural History. Island Press. Washington, DC.
  • Moler, P.E. 1985a. Home range and seasonal activity in the eastern indigo snake, Drymarchon corais couperi, in northern Florida. Final performance report, Study E-1-06, III-A-5. Florida Game and Fresh Water Fish Commission; Tallahassee, FL.
  • Moler, P.E. 1985b. Distribution of the eastern indigo snake, Drymarchon corais couperi, in Florida. Herpetological Review 16(2):37-38.
  • Moler, P.E. 1992. Eastern indigo snake. Pps 181 - 196 in: P.E. Moler (ed). Rare and Endangered Biota of Florida, Volume III, Amphibians and Reptiles. University Press of Florida, Gainesville, FL.
  • Shaw, C.E. 1959. Longevity of snakes in the U.S. as of January 1, 1959. Copeia 1959(4):336-337.
  • Speake, D.W. 1993. Indigo snake recovery plan revision. Final report to the U.S.Fish and Wildlife Service; Jacksonville, Florida.
  • Speake, D.W., and R.H. Mount. 1973. Some possible ecological effects of "rattlesnake roundups" in the southeastern coastal plain. Proceedings of the annual conference of the Southeastern Association of Fish and Wildlife Agencies 27:267-277.
  • Speake, D.W., J.A. McGlincy, and T.R. Colvin. 1978. Ecology and managementof the eastern indigo snake in Georgia: A progress report. Pages 64-73 in: R.R. Odum and L. Landers, (eds.), Proceedings of rare and endangered wildlife symposium, Georgia Department of Natural Resources, Game and Fish Division, Technical Bulletin WL 4.
  • Speake, D.W., and J.A. McGlincy, 1981. Response of indigo snakes to gassing of their dens. Proceedings of the annual conference of the Southeastern Association of Fish and Wildlife Agencies. 35:135-138.
  • Speake, D.W., D. McGlincy, and C. Smith. 1987. Captive breeding andexperimental reintroduction of the eastern indigo snake. Pps. 84 - 90 in:R.R. Odom, K.A. Riddleberger, and J.C. Ozier (eds.), Proceedings. 3rd Southeastern Nongame and Endangered Wildlife Symposium, Georgia Department of Natural Resources, Game and Fish Division.
  • Steiner, T.M., O.L. Bass, Jr., and J.A. Kushlan. 1983. Status of the eastern indigo snake in southern Florida National Parks and vicinity. South FloridaResearch Center Report SFRC-83/01, Everglades National Park; Homestead, Florida.U.S. Fish and Wildlife Service USFWS). 1982. Eastern indigo snake recovery plan. U.S. Fish and Wildlife Service, Atlanta, Georgia.U.S. Fish and Wildlife Service (USFWS). 1999. South Florida multi-speciesrecovery plan. Atlanta, GA. 2,172 pp.
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The diet of the Indigo Snake includes small mammals, birds, frogs, snakes (including even cottonmouths and rattlenakes), lizards, and young turtles. The Indigo Snake is not a constrictor, instead immobilizing food with its jaws. (Behler 1979; Conant and Collins 1991)

Although the diet consists mainly of vertebrates, based on a single record Rossi and Lewis (1994) suggested that in some microhabitats Philomycus slugs could be an important food source for hatchling and juvenile Eastern Indigo Snakes.

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Associations

Ecosystem Roles

Eastern indigo snakes occupy abandoned gopher tortoise burrows, where they seek protection and reproduce. After eastern indigo snake young hatch, they may remain in the nest for a day or two before dispersing. Eastern indigo snakes also help control populations of rodents and other snakes, including venomous snakes, in their home range.

Mutualist Species:

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Predation

Humans are an important threat to eastern indigo snakes. At adult size they have few natural predators, but smaller or younger snakes may be taken by larger predators, such as large hawks. If eastern indigo snakes are threatened, they will first try to retreat quickly. If retreat is not possible, these snakes will display intimidating behavior when confronted by a potential threat. These behaviors include flattening their heads, hissing, and vibrating their tails. However, they rarely bite humans. Eastern indigo snakes protect themselves by hiding in burrows and by behaving cryptically. Their coloration may also help to protect them somewhat.

Known Predators:

Anti-predator Adaptations: cryptic

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Drymarchon couperi can often be found in association with gopher tortoises (Gopherus polyphemus) and other organisms that share tortoise burrows, including the eastern diamondback rattlesnake (Croatalus adamanteus).
  • Ashton R. and P. Ashton. 1981. Handbook of Reptiles and Amphibians of Florida. Windward Publishing, Inc. Miami, FL.
  • Bogert, C. and R. Cowles. 1947. Results of the Archbold expeditions.No. 58. Moisture loss in relation to habitat selection in some Floridian reptiles. American Museum Noviciates 1358:1 - 55.
  • Carson, H. 1945. Delayed fertilization in a captive indigo snake with a note of feeding and shedding. Copeia 1945(4):222-224.
  • Conant R. and J.T. Collins. 1991. A Field Guide to Reptiles and Amphibians.Houghton Mifflin Company, Boston, MA.
  • Hallam, C.O., K. Wheaton, and R. Fischer. 1998. Species profile: Eastern indigo snake (Drymarchon corais couperi) on military installations in the Southeastern United States. Technical report SERDP-98-2, March 1998. Strategic Environmental Research and Development Program, U.S. Army Corps. of Engineers, Waterways Experiment Station, Vicksburg, MS.
  • King, F.W. and K.L. Krysko. 2000. Online Guide to the Snakes of Florida. Florida Museum of Natural History, University of Florida, Gainesville, FL. 266 pp. Available at http://www.flmnh.ufl.edu/natsci/herpetology/fl-guide/onlineguide.htm.
  • Lawler, H.E. 1977. The status of Drymarchon corais couperi (Holbrook), the eastern indigo snake, in the southeastern USA. Herpetological Review 8(3):76-79.
  • Lazell, J. 1989. Wildlife of the Florida Keys: a Natural History. Island Press. Washington, DC.
  • Moler, P.E. 1985a. Home range and seasonal activity in the eastern indigo snake, Drymarchon corais couperi, in northern Florida. Final performance report, Study E-1-06, III-A-5. Florida Game and Fresh Water Fish Commission; Tallahassee, FL.
  • Moler, P.E. 1985b. Distribution of the eastern indigo snake, Drymarchon corais couperi, in Florida. Herpetological Review 16(2):37-38.
  • Moler, P.E. 1992. Eastern indigo snake. Pps 181 - 196 in: P.E. Moler (ed). Rare and Endangered Biota of Florida, Volume III, Amphibians and Reptiles. University Press of Florida, Gainesville, FL.
  • Shaw, C.E. 1959. Longevity of snakes in the U.S. as of January 1, 1959. Copeia 1959(4):336-337.
  • Speake, D.W. 1993. Indigo snake recovery plan revision. Final report to the U.S.Fish and Wildlife Service; Jacksonville, Florida.
  • Speake, D.W., and R.H. Mount. 1973. Some possible ecological effects of "rattlesnake roundups" in the southeastern coastal plain. Proceedings of the annual conference of the Southeastern Association of Fish and Wildlife Agencies 27:267-277.
  • Speake, D.W., J.A. McGlincy, and T.R. Colvin. 1978. Ecology and managementof the eastern indigo snake in Georgia: A progress report. Pages 64-73 in: R.R. Odum and L. Landers, (eds.), Proceedings of rare and endangered wildlife symposium, Georgia Department of Natural Resources, Game and Fish Division, Technical Bulletin WL 4.
  • Speake, D.W., and J.A. McGlincy, 1981. Response of indigo snakes to gassing of their dens. Proceedings of the annual conference of the Southeastern Association of Fish and Wildlife Agencies. 35:135-138.
  • Speake, D.W., D. McGlincy, and C. Smith. 1987. Captive breeding andexperimental reintroduction of the eastern indigo snake. Pps. 84 - 90 in:R.R. Odom, K.A. Riddleberger, and J.C. Ozier (eds.), Proceedings. 3rd Southeastern Nongame and Endangered Wildlife Symposium, Georgia Department of Natural Resources, Game and Fish Division.
  • Steiner, T.M., O.L. Bass, Jr., and J.A. Kushlan. 1983. Status of the eastern indigo snake in southern Florida National Parks and vicinity. South FloridaResearch Center Report SFRC-83/01, Everglades National Park; Homestead, Florida.U.S. Fish and Wildlife Service USFWS). 1982. Eastern indigo snake recovery plan. U.S. Fish and Wildlife Service, Atlanta, Georgia.U.S. Fish and Wildlife Service (USFWS). 1999. South Florida multi-speciesrecovery plan. Atlanta, GA. 2,172 pp.
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Foster et al. (2000) studied the parasites of 21 Eastern Indigo Snakes in Florida, identifying 19 different parasites that included 2 species of trematodes, 3 cestodes, 10 nematodes, 2 acanthocephalans, 1 pentastomid, and 1 tick.

Hyslop et al. (2009) and others have found that Eastern Indigo Snakes are often associated with the burrows of Gopher Tortoises (Gopherus polyphemus).

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Population Biology

Number of Occurrences

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 81 - 300

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.

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Global Abundance

10,000 - 100,000 individuals

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).

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Though they occur throughout Florida, eastern indigo snake populations are declining to the point where they are considered rare in many areas.
  • Ashton R. and P. Ashton. 1981. Handbook of Reptiles and Amphibians of Florida. Windward Publishing, Inc. Miami, FL.
  • Bogert, C. and R. Cowles. 1947. Results of the Archbold expeditions.No. 58. Moisture loss in relation to habitat selection in some Floridian reptiles. American Museum Noviciates 1358:1 - 55.
  • Carson, H. 1945. Delayed fertilization in a captive indigo snake with a note of feeding and shedding. Copeia 1945(4):222-224.
  • Conant R. and J.T. Collins. 1991. A Field Guide to Reptiles and Amphibians.Houghton Mifflin Company, Boston, MA.
  • Hallam, C.O., K. Wheaton, and R. Fischer. 1998. Species profile: Eastern indigo snake (Drymarchon corais couperi) on military installations in the Southeastern United States. Technical report SERDP-98-2, March 1998. Strategic Environmental Research and Development Program, U.S. Army Corps. of Engineers, Waterways Experiment Station, Vicksburg, MS.
  • King, F.W. and K.L. Krysko. 2000. Online Guide to the Snakes of Florida. Florida Museum of Natural History, University of Florida, Gainesville, FL. 266 pp. Available at http://www.flmnh.ufl.edu/natsci/herpetology/fl-guide/onlineguide.htm.
  • Lawler, H.E. 1977. The status of Drymarchon corais couperi (Holbrook), the eastern indigo snake, in the southeastern USA. Herpetological Review 8(3):76-79.
  • Lazell, J. 1989. Wildlife of the Florida Keys: a Natural History. Island Press. Washington, DC.
  • Moler, P.E. 1985a. Home range and seasonal activity in the eastern indigo snake, Drymarchon corais couperi, in northern Florida. Final performance report, Study E-1-06, III-A-5. Florida Game and Fresh Water Fish Commission; Tallahassee, FL.
  • Moler, P.E. 1985b. Distribution of the eastern indigo snake, Drymarchon corais couperi, in Florida. Herpetological Review 16(2):37-38.
  • Moler, P.E. 1992. Eastern indigo snake. Pps 181 - 196 in: P.E. Moler (ed). Rare and Endangered Biota of Florida, Volume III, Amphibians and Reptiles. University Press of Florida, Gainesville, FL.
  • Shaw, C.E. 1959. Longevity of snakes in the U.S. as of January 1, 1959. Copeia 1959(4):336-337.
  • Speake, D.W. 1993. Indigo snake recovery plan revision. Final report to the U.S.Fish and Wildlife Service; Jacksonville, Florida.
  • Speake, D.W., and R.H. Mount. 1973. Some possible ecological effects of "rattlesnake roundups" in the southeastern coastal plain. Proceedings of the annual conference of the Southeastern Association of Fish and Wildlife Agencies 27:267-277.
  • Speake, D.W., J.A. McGlincy, and T.R. Colvin. 1978. Ecology and managementof the eastern indigo snake in Georgia: A progress report. Pages 64-73 in: R.R. Odum and L. Landers, (eds.), Proceedings of rare and endangered wildlife symposium, Georgia Department of Natural Resources, Game and Fish Division, Technical Bulletin WL 4.
  • Speake, D.W., and J.A. McGlincy, 1981. Response of indigo snakes to gassing of their dens. Proceedings of the annual conference of the Southeastern Association of Fish and Wildlife Agencies. 35:135-138.
  • Speake, D.W., D. McGlincy, and C. Smith. 1987. Captive breeding andexperimental reintroduction of the eastern indigo snake. Pps. 84 - 90 in:R.R. Odom, K.A. Riddleberger, and J.C. Ozier (eds.), Proceedings. 3rd Southeastern Nongame and Endangered Wildlife Symposium, Georgia Department of Natural Resources, Game and Fish Division.
  • Steiner, T.M., O.L. Bass, Jr., and J.A. Kushlan. 1983. Status of the eastern indigo snake in southern Florida National Parks and vicinity. South FloridaResearch Center Report SFRC-83/01, Everglades National Park; Homestead, Florida.U.S. Fish and Wildlife Service USFWS). 1982. Eastern indigo snake recovery plan. U.S. Fish and Wildlife Service, Atlanta, Georgia.U.S. Fish and Wildlife Service (USFWS). 1999. South Florida multi-speciesrecovery plan. Atlanta, GA. 2,172 pp.
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General Ecology

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).

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Ecology

Home range estimates for Eastern Indigo Snakes in peninsular Florida ranged from 1.9 to 150 hectares for females and 1.6 to 327 hectares for males. Summer home ranges tend to be much larger than winter home ranges. A recent telemetry study in Georgia estimated home ranges of 35 to 354 hectares for females and 140 to 1530 hectares for males. Especially in fall and winter, Eastern Indigo Snakes are often associated with Gopher Tortoise burrows. These snakes seem to avoid paved roads, urban areas, and deciduous forest. Eastern Indigo Snakes exhibit a homing instinct and may return annually to previously used winter dens. (USFWS 2008 and references therein)

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Life History and Behavior

Behavior

Communication and Perception

Eastern indigo snake females use pheromones to attract males. Some researchers take advantage of this method of communication to attract males and capture them for research.

Communication Channels: visual ; tactile ; chemical

Perception Channels: visual ; tactile ; vibrations ; chemical

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Behaviour

When cornered, the Eastern Indigo Snake flattens its neck vertically (not horizontally as in the hognose snakes), hisses, and vibrates its tail, producing a rattling sound. When caught, it seldom attempts to bite. Captive Eastern Indigo Snakes are usually restless and keep on the move when handled. (Conant and Collins 1991)

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Cyclicity

Comments: Primarily diurnal, but partly nocturnal in some areas (McCranie 1980). Inactive for a week or two prior to shedding (Moler 1992).

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Life Cycle

Development

Eastern indigo snakes are sexually dimorphic in growth as well. Males grow to larger sizes and females may halt growth to focus their energy on maintaining the production of eggs. Growth rates are higher in younger individuals.

  • Ditmars, R. 1939. A field book to North American Snakes. New York: Doran & Company.
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Life Expectancy

Lifespan/Longevity

The average lifespan of a wild eastern indigo snake is commonly 17 years. However, they can survive up to 21 years in the wild. The longest living indigo snake lived in captivity for 25 years and 11 months.

Range lifespan

Status: wild:
12 to 21 years.

Average lifespan

Status: wild:
17 years.

Range lifespan

Status: captivity:
16 to 25 years.

Average lifespan

Status: captivity:
23 years.

Typical lifespan

Status: wild:
15 to 21 years.

Average lifespan

Status: wild:
17 years.

Typical lifespan

Status: captivity:
16 to 25 years.

Average lifespan

Status: captivity:
23 years.

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The Eastern Indigo Snake is long-lived; one captive individual lived nearly 26 years (Behler 1979).

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Reproduction

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).

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Female eastern indigo snakes signal their readiness to mate by producing pheromones. When the scent is picked up by a male indigo snake, they track down the scent until they come into contact with the female. If other males are present, they will typically engage in ritual combat dances. During these dances, both males will intertwine their bodies and try to force the other's head to the ground. The winner mates with the female. Eastern indigo snakes have a polygynandrous mating system; males and females have multiple mates.

Mating System: polygynandrous (promiscuous)

In northern Florida, where most research on reproduction cycles has been conducted, the breeding season is from November to April. Females deposit their eggs from May to June. Females lay from 4 to 12 eggs, usually in vacated animal burrows, such as those of gopher tortoises, fallen logs, or some other sheltered burrow. Young hatch in about 3 months, usually in August and September. The breeding season may be extended in parts of south central Florida. Some researchers suggest that can store sperm and delay fertilization, but this idea has yet to be supported by evidence.

Breeding interval: Eastern indigo snakes breed once a year.

Breeding season: Eastern indigo snakes mate from November to April and lay eggs in May and June.

Range number of offspring: 4 to 12.

Average number of offspring: 7.

Average age at sexual or reproductive maturity (female): 3-4 years.

Average age at sexual or reproductive maturity (male): 3-4 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); oviparous

Eastern indigo snake hatchlings are born at an average size of 30.48 cm long. They grow rapidly and often reach adult size in 2 to 3 years. Eastern indigo snake females invest in young through supplying the egg and finding a safe place to lay their eggs. There is no further parental investment.

Parental Investment: no parental involvement; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female)

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Drymarchon couperi reaches sexual maturity at approximately 3 - 4 years of age (Hallam et al. 1998). In North Florida, breeding occurs November - April. Wild females lay clutches of 4 - 12 eggs in May or June (Moler 1992), while captive females have an average clutch size of 9 -20 (Speake et al. 1987). Hatching takes place after approximately 3 months, with peaks occurring August - September. In south-central Florida, breeding occurs June - January, with egg laying taking place April - July. Hatching generally occurs from mid-summer through early Fall (USFWS 1999). Females can apparently store sperm and delay fertilization of eggs. Carson (1945) reported a on a female indigo snake that laid a clutch of 5 eggs after having been isolated for more than 4 years. There have also been anecdotal reports of parthenogenetic reproduction in virginal snakes (USFWS 1999).
  • Ashton R. and P. Ashton. 1981. Handbook of Reptiles and Amphibians of Florida. Windward Publishing, Inc. Miami, FL.
  • Bogert, C. and R. Cowles. 1947. Results of the Archbold expeditions.No. 58. Moisture loss in relation to habitat selection in some Floridian reptiles. American Museum Noviciates 1358:1 - 55.
  • Carson, H. 1945. Delayed fertilization in a captive indigo snake with a note of feeding and shedding. Copeia 1945(4):222-224.
  • Conant R. and J.T. Collins. 1991. A Field Guide to Reptiles and Amphibians.Houghton Mifflin Company, Boston, MA.
  • Hallam, C.O., K. Wheaton, and R. Fischer. 1998. Species profile: Eastern indigo snake (Drymarchon corais couperi) on military installations in the Southeastern United States. Technical report SERDP-98-2, March 1998. Strategic Environmental Research and Development Program, U.S. Army Corps. of Engineers, Waterways Experiment Station, Vicksburg, MS.
  • King, F.W. and K.L. Krysko. 2000. Online Guide to the Snakes of Florida. Florida Museum of Natural History, University of Florida, Gainesville, FL. 266 pp. Available at http://www.flmnh.ufl.edu/natsci/herpetology/fl-guide/onlineguide.htm.
  • Lawler, H.E. 1977. The status of Drymarchon corais couperi (Holbrook), the eastern indigo snake, in the southeastern USA. Herpetological Review 8(3):76-79.
  • Lazell, J. 1989. Wildlife of the Florida Keys: a Natural History. Island Press. Washington, DC.
  • Moler, P.E. 1985a. Home range and seasonal activity in the eastern indigo snake, Drymarchon corais couperi, in northern Florida. Final performance report, Study E-1-06, III-A-5. Florida Game and Fresh Water Fish Commission; Tallahassee, FL.
  • Moler, P.E. 1985b. Distribution of the eastern indigo snake, Drymarchon corais couperi, in Florida. Herpetological Review 16(2):37-38.
  • Moler, P.E. 1992. Eastern indigo snake. Pps 181 - 196 in: P.E. Moler (ed). Rare and Endangered Biota of Florida, Volume III, Amphibians and Reptiles. University Press of Florida, Gainesville, FL.
  • Shaw, C.E. 1959. Longevity of snakes in the U.S. as of January 1, 1959. Copeia 1959(4):336-337.
  • Speake, D.W. 1993. Indigo snake recovery plan revision. Final report to the U.S.Fish and Wildlife Service; Jacksonville, Florida.
  • Speake, D.W., and R.H. Mount. 1973. Some possible ecological effects of "rattlesnake roundups" in the southeastern coastal plain. Proceedings of the annual conference of the Southeastern Association of Fish and Wildlife Agencies 27:267-277.
  • Speake, D.W., J.A. McGlincy, and T.R. Colvin. 1978. Ecology and managementof the eastern indigo snake in Georgia: A progress report. Pages 64-73 in: R.R. Odum and L. Landers, (eds.), Proceedings of rare and endangered wildlife symposium, Georgia Department of Natural Resources, Game and Fish Division, Technical Bulletin WL 4.
  • Speake, D.W., and J.A. McGlincy, 1981. Response of indigo snakes to gassing of their dens. Proceedings of the annual conference of the Southeastern Association of Fish and Wildlife Agencies. 35:135-138.
  • Speake, D.W., D. McGlincy, and C. Smith. 1987. Captive breeding andexperimental reintroduction of the eastern indigo snake. Pps. 84 - 90 in:R.R. Odom, K.A. Riddleberger, and J.C. Ozier (eds.), Proceedings. 3rd Southeastern Nongame and Endangered Wildlife Symposium, Georgia Department of Natural Resources, Game and Fish Division.
  • Steiner, T.M., O.L. Bass, Jr., and J.A. Kushlan. 1983. Status of the eastern indigo snake in southern Florida National Parks and vicinity. South FloridaResearch Center Report SFRC-83/01, Everglades National Park; Homestead, Florida.U.S. Fish and Wildlife Service USFWS). 1982. Eastern indigo snake recovery plan. U.S. Fish and Wildlife Service, Atlanta, Georgia.U.S. Fish and Wildlife Service (USFWS). 1999. South Florida multi-speciesrecovery plan. Atlanta, GA. 2,172 pp.
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The Eastern Indigo Snake mates from November to February. It deposits 5 to 12 leathery eggs, 76 to 102 mm long, in April or May. Hatchlings appear in late July to October. (Behler 1979)

Sexual maturity is reached at about 1.5 meters in length. Two captive females bred at 40 and 41 months of age. Average clutch size of 20 females removed from the wild and laying eggs the following spring was 9.4 eggs. In captivity, Eastern Indigo Snakes typically lay eggs every year. (USFWS 2008 and references therein)

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Evolution and Systematics

Evolution

Systematics and Taxonomy

Although at the time it was listed as a federally threatened species the Eastern Indigo Snake was treated as a subspecies, Drymarchon corais couperi, it is now accepted as a full species, Drymarchon couperi (USFWS 2008 and references therein).

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Conservation

Conservation Status

National NatureServe Conservation Status

United States

Rounded National Status Rank: N3 - Vulnerable

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NatureServe Conservation Status

Rounded Global Status Rank: 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.

Intrinsic Vulnerability: Moderately vulnerable

Other Considerations: Because individuals require large areas and a variety of habitats, very large areas (perhaps 10,000 acres) may be necessary for long-term population viability. Presence of gopher tortoise (burrows used for shelter) may be important to this snake in xeric habitats.

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IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2007

Assessor/s
Hammerson, G.A.

Reviewer/s
Cox, N., Chanson, J.S. & Stuart, S.N. (Global Reptile Assessment Coordinating Team)

Contributor/s

Justification
Listed as Least Concern in view of the fairly large range and area of occupancy and presumed large population size. Many subpopulations exist, but a large proportion may be of low viability. Area of occupancy and abundance likely are declining but probably not fast enough for listing in a more threatened category.

History
  • 1996
    Not Evaluated
  • 1994
    Vulnerable
    (Groombridge 1994)
  • 1990
    Vulnerable
    (IUCN 1990)
  • 1988
    Vulnerable
    (IUCN Conservation Monitoring Centre 1988)
  • 1986
    Vulnerable
    (IUCN Conservation Monitoring Centre 1986)
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Humans present that greatest threat to eastern indigo snakes. Appropriate habitat is destroyed during roadway and housing construction and logging and agricultural activities. Domesticated animals and pesticides also negatively affect populations. Eastern indigo snakes are sometimes accidentally gassed in their burrows by rattlesnake poachers and they were frequently and illegally taken from their natural habitats and sold as pets. Eastern indigo snakes were placed on the U.S. endangered species list in 1971. Since then, they have been protected by the United States Fish and Wildlife Service and the Florida Fish and Wildlife Conservation Commission. Under this protection, it is illegal to possess, harm or harass eastern indigo snakes and permits are required to keep or transport them. Several adult snakes have been returned to sandhill regions and are being monitored for conservation research purposes. Populations remain threatened.

US Federal List: endangered

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

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Global Short Term Trend: Relatively stable to decline of 30%

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.

Global Long Term Trend: Relatively stable to decline of 50%

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.

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Population

Population
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. The total adult population size is unknown but probably exceeds 10,000 (conservatively assuming a density of at least 1 adult per sq. kilometer in an area of occupancy of at least 20,000 sq. km). The 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. 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.

Population Trend
Decreasing
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Threats

Degree of Threat: High

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).

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Major Threats
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).
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Drymarchon couperi has been listed as Threatened in the State of Florida since 1971. It has been Federally listed as Threatened since Jan 31, 1978. The decline of eastern indigo snakes is primarily the result of over-harvesting for the pet trade, but habitat loss and degradation, and the gassing of tortoise burrows to collect rattlesnakes have also heavily impacted the species (Speake and Mount 1973; Speake and McGlincy 1981).Law enforcement of prohibitions against unauthorized take has reduced pressure on the indigo snake, but has not eliminated it (Moler 1992). Because this snake has a large home range, it may be especially susceptible to habitat loss and fragmentation (Lawler 1977; Moler 1985a). Some estimates suggest that habitat losses of approximately 5% per year continue to occur (Lawler 1977). Increased human population growth also increases the possibility of increased snake mortality due to deaths from property owners and domestic pets. It is expected that the increasing trend toward altering natural areas for agricultural, residential and commercial purposes will result in a large number of isolated groups which cannot support a sufficient number of individuals to ensure continued survival. Recovery of Drymarchon couperi requires protection and preservation of large expanses of unaltered habitat (USFWS 1999). However, relatively little is currently known about the minimum population size required to maintain and recover the species, though research and population modeling efforts are underway to address these issues.Management activities being currently undertaken include prescribed burning to maintain optimum habitat quality, maintenance of a captive breeding colony, public outreach and education, and landowner cooperation to conserve snake populations on privately held lands.
  • Ashton R. and P. Ashton. 1981. Handbook of Reptiles and Amphibians of Florida. Windward Publishing, Inc. Miami, FL.
  • Bogert, C. and R. Cowles. 1947. Results of the Archbold expeditions.No. 58. Moisture loss in relation to habitat selection in some Floridian reptiles. American Museum Noviciates 1358:1 - 55.
  • Carson, H. 1945. Delayed fertilization in a captive indigo snake with a note of feeding and shedding. Copeia 1945(4):222-224.
  • Conant R. and J.T. Collins. 1991. A Field Guide to Reptiles and Amphibians.Houghton Mifflin Company, Boston, MA.
  • Hallam, C.O., K. Wheaton, and R. Fischer. 1998. Species profile: Eastern indigo snake (Drymarchon corais couperi) on military installations in the Southeastern United States. Technical report SERDP-98-2, March 1998. Strategic Environmental Research and Development Program, U.S. Army Corps. of Engineers, Waterways Experiment Station, Vicksburg, MS.
  • King, F.W. and K.L. Krysko. 2000. Online Guide to the Snakes of Florida. Florida Museum of Natural History, University of Florida, Gainesville, FL. 266 pp. Available at http://www.flmnh.ufl.edu/natsci/herpetology/fl-guide/onlineguide.htm.
  • Lawler, H.E. 1977. The status of Drymarchon corais couperi (Holbrook), the eastern indigo snake, in the southeastern USA. Herpetological Review 8(3):76-79.
  • Lazell, J. 1989. Wildlife of the Florida Keys: a Natural History. Island Press. Washington, DC.
  • Moler, P.E. 1985a. Home range and seasonal activity in the eastern indigo snake, Drymarchon corais couperi, in northern Florida. Final performance report, Study E-1-06, III-A-5. Florida Game and Fresh Water Fish Commission; Tallahassee, FL.
  • Moler, P.E. 1985b. Distribution of the eastern indigo snake, Drymarchon corais couperi, in Florida. Herpetological Review 16(2):37-38.
  • Moler, P.E. 1992. Eastern indigo snake. Pps 181 - 196 in: P.E. Moler (ed). Rare and Endangered Biota of Florida, Volume III, Amphibians and Reptiles. University Press of Florida, Gainesville, FL.
  • Shaw, C.E. 1959. Longevity of snakes in the U.S. as of January 1, 1959. Copeia 1959(4):336-337.
  • Speake, D.W. 1993. Indigo snake recovery plan revision. Final report to the U.S.Fish and Wildlife Service; Jacksonville, Florida.
  • Speake, D.W., and R.H. Mount. 1973. Some possible ecological effects of "rattlesnake roundups" in the southeastern coastal plain. Proceedings of the annual conference of the Southeastern Association of Fish and Wildlife Agencies 27:267-277.
  • Speake, D.W., J.A. McGlincy, and T.R. Colvin. 1978. Ecology and managementof the eastern indigo snake in Georgia: A progress report. Pages 64-73 in: R.R. Odum and L. Landers, (eds.), Proceedings of rare and endangered wildlife symposium, Georgia Department of Natural Resources, Game and Fish Division, Technical Bulletin WL 4.
  • Speake, D.W., and J.A. McGlincy, 1981. Response of indigo snakes to gassing of their dens. Proceedings of the annual conference of the Southeastern Association of Fish and Wildlife Agencies. 35:135-138.
  • Speake, D.W., D. McGlincy, and C. Smith. 1987. Captive breeding andexperimental reintroduction of the eastern indigo snake. Pps. 84 - 90 in:R.R. Odom, K.A. Riddleberger, and J.C. Ozier (eds.), Proceedings. 3rd Southeastern Nongame and Endangered Wildlife Symposium, Georgia Department of Natural Resources, Game and Fish Division.
  • Steiner, T.M., O.L. Bass, Jr., and J.A. Kushlan. 1983. Status of the eastern indigo snake in southern Florida National Parks and vicinity. South FloridaResearch Center Report SFRC-83/01, Everglades National Park; Homestead, Florida.U.S. Fish and Wildlife Service USFWS). 1982. Eastern indigo snake recovery plan. U.S. Fish and Wildlife Service, Atlanta, Georgia.U.S. Fish and Wildlife Service (USFWS). 1999. South Florida multi-speciesrecovery plan. Atlanta, GA. 2,172 pp.
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Loss of native habitat supporting Eastern Indigo Snakes is ongoing as a result of development and urbanization. Habitat loss is especially problematic for this species because of its relatively large home range. (USFWS 2008)

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Legislation

The Eastern Indigo Snake was listed as threatened under the U.S. Endangered Species Act in 1978 (Federal Register, 43 FR 4026-4029).

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Management

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 and 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.

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.

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Global Protection: Few to several (1-12) occurrences appropriately protected and managed

Comments: Several occurrences are on managed areas (federal, state, and private), but these are still subject to some unauthorized collection. Many managed areas are too small to support a viable population by themselves.

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.

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Conservation Actions

Conservation Actions
Several occurrences are on managed areas (federal, state, and private), but these are still subject to some unauthorized collection. Many managed areas are too small to support a viable population by themselves.
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Because of their large home ranges and other behavioral traits, it is estimated that maintaining a viable population of Eastern Indigo Snakes requires at least 1000 hectares. The lack of reliable survey methods for this snake has made it difficult to obtain basic demographic and trend data and carry out effective conservation planning. One intriguing possibility that has shown at least some promise for locating Indigo snakes has been training dogs to track them. (USFWS 2008 and references therein)

Although development has been generally extremely harmful to the Eastern Indigo Snake, in south Florida, agricultural sites such as sugar cane fields and canal banks through citrus groves created in former wetland areas are occupied by Eastern Indigo Snakes. Historically, these snakes would have occupied only higher elevation sites within the wetlands. Agriculture and its associated canal systems, however, have brought increased numbers of rodents and other snake species that are eaten by Eastern Indigos, resulting in higher densities of Eastern Indigo Snakes in these areas than would have been present in the past. Efforts to restore natural wetlands in some of these areas may actually reduce resident populations of Eastern Indigo Snakes. (USFWS 2008)

Current efforts to secure the future of the Eastern Indigo Snake are focused on land acquisition, captive breeding snakes to establish new populations in the wild, and habitat management (USFWS 2008).

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Relevance to Humans and Ecosystems

Benefits

Economic Importance for Humans: Negative

Eastern indigo snakes are not a threat to humans. Their status as endangered species sometimes interferes with construction projects.

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Economic Importance for Humans: Positive

Eastern indigo snakes were commonly used in the pet trade before this became illegal. They were prized in the pet trade for their docile nature and hardiness. Currently, some are bred in captivity as pets but keeping eastern indigo snakes is regulated and permits are required. Now though, to keep an indigo snake in a one's possession one must have a permit or it is illegal. Eastern indigo snakes are important predators of rodents and venomous snakes, which helps to regulate populations of these potentially harmful animals. Eastern indigo snakes are not aggressive and often live near humans without any negative interactions, aside from human persecution resulting from misunderstanding about snakes and their important ecological roles.

Positive Impacts: controls pest population

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Wikipedia

Eastern indigo snake

The Eastern Indigo Snake (Drymarchon couperi) is a species of large nonvenomous colubrid snake native to the Eastern United States. It is of note as being the longest native snake species in the U.S.

Description[edit]

The Eastern Indigo Snake has even blue-black dorsal and lateral scales, with some specimens having a reddish-orange to tan color on the throat, cheeks, and chin. This snake received its name from the glossy iridescent ventral scales which can be seen as blackish-purple in bright light. This smooth-scaled snake is considered to be the longest native snake species in the United States. The longest recorded specimen measured 2.8 m (9.2 ft). Unlike many snakes, mature male indigo snakes are slightly larger than females. A typical mature male measures 2.13–2.36 m (7.0–7.7 ft) and weighs 3.2–4.5 kg (7.1–9.9 lb), whereas a mature female typically measures around 2 m (6.6 ft) in length and weighs 1.8–2.7 kg (4.0–6.0 lb).[3] In specimens over 2.6 m (8.5 ft), these snakes can weigh up to 5 kg (11 lb).[4] Although the indigo snake is heavier on average, unusually large specimens of the co-occurring eastern diamondback rattlesnake can outweigh them.[5]

Taxonomy[edit]

The Eastern Indigo Snake was first described by John Edwards Holbrook in 1842. The species was considered monotypic with 12 subspecies until the early 1990s when it was elevated to full species status according to The Society for the Study of Amphibians and Reptiles, in their official names list.

The Latin name for the genus Drymarchon roughly translates to “Lord of the Forest”. It is composed of the Greek words Drymos (Δρυμός), meaning "forest", and Archon (ἄρχων), meaning "lord" or "ruler". The specific name is a Latinization of James Couper's surname. Couper brought Holbrook the first specimen from south of the Altamaha River in Wayne County, Georgia.

Common names[edit]

Eastern Indigo Snakes have a number of common names including indigo, blue indigo snake, black snake, blue gopher snake, and blue bull snake.

Distribution[edit]

The Eastern Indigo Snake ranges from southern South Carolina south through Florida and west to Louisiana, Mississippi, and Alabama.[1] A related species, the Texas indigo snake (Drymarchon melanurus erebennus), is found in southern Texas and Mexico.[6]

Conservation status[edit]

Because of habitat loss, the Eastern Indigo Snake is listed as a federally threatened species in Georgia and Florida.[7] The Alabama Department of Conservation and Natural Resources has listed the species as possibly extirpated within the state.[8]

Preferred habitat[edit]

Eastern Indigo Snakes frequent flatwoods, hammocks, dry glades, stream bottoms, cane fields, riparian thickets, and high ground with well-drained, sandy soils.[6] In Georgia, snakes prefer excessively drained, deep sandy soils along major streams, as well as xeric sandridge habitats.[9] Xeric slash pine plantations seem to be preferred over undisturbed longleaf pine habitats.[10] Habitat selection varies seasonally. From December to April, Eastern Indigo Snakes prefer sandhill habitats; from May to July snakes shift from winter dens to summer territories; from August through November they are located more frequently in shady creek bottoms than during other seasons.[11]

The Eastern Indigo Snake is most abundant in the sandhill plant communities of Florida and Georgia. These communities are primarily scrub oak-longleaf pine (Pinus palustris) with occasional live oak (Quercus virginiana), laurel oak (Q. laurifolia), Chapman's oak (Q. chapmanii), and myrtle oak (Q. myrtifolia). Other communities include longleaf pine-turkey oak (Q. laevis), slash pine (Pinus elliottii)-scrub oak, pine flatwoods, and pine-mesic hardwoods.[9]

Cover requirements[edit]

Because the cover requirements of Eastern Indigo Snakes change seasonally, maintaining corridors that link the different habitats used is important. From the spring through fall snakes must be able to travel from sandhill communities and upland pine-hardwood communities to creek bottoms and agricultural fields.[11] In winter, indigo snakes den in gopher tortoise burrows, which are usually found in open pine forests with dense herbaceous understories.[10] Burrows need to be in areas where there is no flooding. Eastern Indigo Snakes heavily use debris piles left from site-preparation operations on tree plantations.[10] These piles are often destroyed for cosmetic reasons but should be left intact because they provide important hiding cover for both the snake and its prey. Summer home ranges for the indigo snake can be as large as 273 acres (229 ha).[11]

Food habits and behavior[edit]

The Eastern Indigo Snake is carnivorous, like all snakes, and will eat any other small animal it can overpower. It has been known to kill its prey by wildly beating it against nearby objects. Captive specimen are frequently fed dead prey to prevent injury to the snake from this violent method of subduing its prey. Its diet has been known to include other snakes (ophiophagy), including venomous ones, as it is immune to the venom of the North American rattlesnakes. Eastern Indigo Snakes eat turtles, lizards, frogs, toads, a variety of small birds and mammals, and eggs.[6][10]

As defensive behavior the Eastern Indigo Snake vertically flattens its neck, hisses, and vibrates its tail. If picked up, it seldom bites.[12]

It often will cohabit with gopher tortoises in their underground burrows, although it will settle for armadillo holes, hollow logs, and debris piles when gopher tortoise burrows can't be found. Hunters, hoping to flush out rattlesnakes, often wind up accidentally killing indigo snakes when they illegally pour gasoline into the burrows of gopher tortoises (a practice referred to as "gassing"), even though the tortoises themselves are endangered and protected.

Predators[edit]

Humans represent the biggest threat to indigo snakes. Highway fatalities, wanton killings, and overcollection for the pet trade adversely affect indigo snake populations. Snakes are taken illegally from the wild for the pet trade. Eastern Indigo Snakes are sometimes "gassed" in their burrows by rattlesnake hunters.[9]

Reproduction[edit]

Eastern Indigo Snakes are oviparous.[13] The eggs are 75–100 mm (3–4 in.) long by 27–32 mm (1-1¼ in.) wide. Only 5–6 eggs are laid. The hatchlings are 600–700 mm (23½–27½ in.) long.[14]

Captivity and care[edit]

Due to its generally docile nature and attractive appearance, some people find it a desirable pet, although its protected status can make owning one, depending on location, illegal without a permit. Only a few states require permits to own an Eastern Indigo Snake, but a federal permit is required to buy one from out of state anywhere in the US. The permit costs $100; information about obtaining one can be found by doing a web search. Most states allow unrestricted in-state sales. To thrive in captivity, this snake requires a larger enclosure than most species do, preferably with something to climb on.

References[edit]

 This article incorporates public domain material from the United States Department of Agriculture document "Drymarchon corais".

  1. ^ a b Hammerson, G.A (2007). "Drymarchon couperi". IUCN Red List of Threatened Species. Version 2010.4. International Union for Conservation of Nature. Retrieved 2 February 2014. 
  2. ^ The Reptile Database. www.reptile-database.org.
  3. ^ Eastern Indigo Snake. The Orianne Society. Retrieved on 2012-11-30.
  4. ^ James C. Godwin. Eastern Indigo Snake Fact Sheet. alaparc.org
  5. ^ Wood, Gerald (1983). The Guinness Book of Animal Facts and Feats. ISBN 978-0-85112-235-9. 
  6. ^ a b c Conant, Roger; Collins, Joseph T. 1991. A Field Guide to Reptiles and Amphibians: Eastern and Central North America. Third Edition. Peterson Field Guide Series No. 12. Houghton Mifflin Company. Boston.
  7. ^ Andrew M. Grosse, University of Georgia – edited by J.D. Willson Eastern Indigo Snake (Drymarchon couperi)
  8. ^ "Snakes in Alabama". Outdoor Alabama. Alabama Department of Conservation and Natural Resources. Retrieved June 6, 2012. 
  9. ^ a b c Diemer, Joan E.; Speake, Dan W. 1983. The distribution of the Eastern Indigo Snake, Drymarchon corais couperi, in Georgia. Journal of Herpetology. 17(3): 256–264
  10. ^ a b c d Landers, J. Larry; Speake, Dan W. 1980. Management needs of sandhill reptiles in southern Georgia. Proceedings, Annual Conference of Southeast Association Fish & Wildlife Agencies. 34: 515–529
  11. ^ a b c Speake, Dan W.; McGlincy, Joe A.; Colvin, Thagard R. 1978. Ecology and management of the Eastern Indigo Snake in Georgia: a progress report. In: Odum, R. R.; Landers, L., eds. Proceedings, Rare and endangered wildlife symposium. Tech. Bull. WL4. Atlanta, GA: Georgia Department of Natural Resources, Game and Fish Division: 64–73
  12. ^ Conant, Roger. 1975. A Field Guide to Reptiles and Amphibians of Eastern and Central North America. Second Edition Houghton Mifflin. Boston. 429 pp. (Drymarchon corais couperi, pp. 186–187, Plate 27, Map 144.)
  13. ^ 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. 365 pp. (Drymarchon corais couperi, pp. 133–135, Figure 32, Plate 14.)
  14. ^ Wright, A.H., and A.A. Wright. 1957. Handbook of Snakes of the United States and Canada. Comstock. Ithaca and London. 1,105 pp. (2 volumes). (Drymarchon corais couperi, pp. 200–203, Figures 20 & 64, Map 21.)

Further reading[edit]

  • Holbrook, J.E. 1842. North American Herpetology; or, A Description of the Reptiles Inhabiting the United States. Vol. III. J.Dobson. Philadelphia. 122 pp. (Coluber couperi, pp. 75–77 & Plate 16.)
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Names and Taxonomy

Taxonomy

Comments: Drymarchon couperi was proposed as a distinct species by Collins (1991), based on previously published (but unspecified) morphological differences and application of the evolutionary species concept. Crother et al. 2008, citing Wuster et al. (2001) listed couperi as a species.

Subspecies couperi was proposed as a distinct species by Collins (1991), based on previously published (but unspecified) morphological differences and application of the evolutionary species concept. Crother et al. 2008, citing Wuster et al. (2001) listed couperi as a species. This database accepts Drymarchon couperi as a species, however, further study is warranted.

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