{{Short description|Species of snake}} {{Use dmy dates|date=June 2020}} {{Speciesbox | name = Eastern indigo snake | image = Eastern Indigo Snake.jpg | status = LC | status_system = IUCN3.1 | status_ref = <ref name=iucn>Hammerson, G.A. (2007). "''Drymarchon couperi'' ". The IUCN Red List of Threatened Species 2007: e.T63773A12714602. https://dx.doi.org/10.2305/IUCN.UK.2007.RLTS.T63773A12714602.en. Accessed on 21 March 2022.</ref> | status2 = LT | status2_system= ESA | status2_ref = <ref name="USFW">{{cite web |url=https://ecos.fws.gov/ecp/species/646 |title=Eastern indigo snake (''Drymarchon couperi)''|website=Environmental Conservation Online System |publisher=U.S. Fish and Wildlife Service|access-date=10 April 2023}}</ref><ref>{{Federal Register|43|4026}}</ref> | genus = Drymarchon | species = couperi | authority = (Holbrook, 1842) | range_map = Drymarchon couperi distribution.png | synonyms = *''Coluber couperi'' <br />{{small|Holbrook, 1842}} *''Georgia couperi'' <br />{{small|— Baird & Girard, 1853}} *''Spilotes couperi'' <br />{{small|— Cope, 1860}} *''Spilotes corais couperi'' <br />{{small|— Lönnberg, 1894}} *''Drymarchon corais couperi'' <br />{{small|— Amaral, 1929}} *''Drymarchon couperi'' <br />{{small|— Crother, 2000}} | synonyms_ref =<ref>{{EMBL species|genus=Drymarchon|species=couperi}}. www.reptile-database.org.</ref> }}

The '''eastern indigo snake''' ('''''Drymarchon couperi''')'' is a species of large, nonvenomous snake in the subfamily Colubrinae of the family Colubridae. Native to the Southeastern United States, it is the longest native snake species in the country.<!-- only the longest in "North America" if using a restrictive and unconventional definition where only the US+Canada are included; Mexico is home to Boa imperator and Cuba to Chilabothrus angulifer --><ref name="nature.org">{{cite web |url=https://www.nature.org/en-us/get-involved/how-to-help/animals-we-protect/eastern-indigo-snake/ |title =Animals We Protect: Eastern Indigo Snake|website=The Nature Conservancy|year=2023|access-date=10 April 2023}}</ref>

thumb|Eastern indigo

==Taxonomy and etymology== ===Taxonomy=== The eastern indigo snake was first described by John Edwards Holbrook in 1842. For many years, the genus ''Drymarchon'' was considered monotypic with one species, ''Drymarchon corais'', with 12 subspecies, until the early 1990s, when ''Drymarchon corais couperi'' was elevated to full species status according to the Society for the Study of Amphibians and Reptiles, in their official names list.

===Etymology=== The generic name, ''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 the surname of American planter James Hamilton Couper (1794&ndash;1866).<ref>Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). ''The Eponym Dictionary of Reptiles''. Baltimore: Johns Hopkins University Press. xiii + 296 pp. {{ISBN|978-1-4214-0135-5}}. (''Drymarchon couperi'', p. 60).</ref> Couper brought Holbrook the type specimen from south of the Altamaha River in Wayne County, Georgia.

===Common names=== ''Drymarchon couperi'' has a number of common names, including '''black snake''', '''blue bull snake''', '''blue gopher snake''', '''blue indigo snake''', '''eastern indigo snake''', and '''indigo snake'''.

==Description== The eastern indigo snake has uniformly blue-black dorsal scales, with some specimens having a reddish-orange to tan color on the throat, cheeks, and chin. This snake received its common name from the glossy, iridescent dorsal and 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.<!-- only the longest in "North America" if using a restrictive and unconventional definition where only the US+Canada are included; Mexico is home to Boa imperator and Cuba to Chilabothrus angulifer --><ref name="nature.org"/> The longest recorded specimen measured {{convert|2.8|m|ft|abbr=on}} in total length (tail included). Unlike many snakes, mature male indigo snakes are slightly larger than females. This is thought to be due to intraspecies competition and combat among males.<ref>{{Cite journal |last1=Stevenson |first1=Dirk J. |last2=Dyer |first2=Karen J. |last3=Willis-Stevenson |first3=Beth A. |date=2003 |title=Survey and Monitoring of the Eastern Indigo Snake in Georgia |journal=Southeastern Naturalist |volume=2 |issue=3 |pages=393–408 |doi=10.1656/1528-7092(2003)002[0393:SAMOTE]2.0.CO;2 |jstor=3878009 |s2cid=86306664 |issn=1528-7092}}</ref> A typical mature male measures {{convert|1.2|-|2.36|m|ft|abbr=on}} in total length, with a reported average of {{convert|1.58|m|ft|abbr=on}}, and weighs {{convert|0.72|-|4.5|kg|lb|abbr=on}}, reportedly averaging {{convert|2.2|kg|lb|abbr=on}}. Males that measure longer than 1.2 m (4 ft) tend to possess weak keels on mid-dorsal scale rows 3–5, while females lack this characteristic.<ref>{{cite journal |last1=Stevenson |first1=Dirk J. |last2=Enge |first2=Kevin M. |last3=Carlile |first3=Lawrence D. |last4=Dyer |first4=Karen J. |last5=Norton |first5=Terry M. |last6=Hyslop |first6=Natalie L. |last7=Kiltie |first7=Richard A. |date=2009 |title=An Eastern Indigo Snake (''Drymarchon couperi)'' Mark-Recapture Study in Southeastern Georgia |url=https://www.herpconbio.org/Volume_4/Issue_1/Stevenson_etal_2009.pdf?t=1621123200063 |journal=Herpetological Conservation and Biology |volume=4 |issue=1 |pages=30–42}}</ref> Mature females typically measure around {{convert|1.1|-|2|m|ft|abbr=on}} in total length, averaging {{convert|1.38|m|ft|abbr=on}}, and weigh {{convert|0.55|-|2.7|kg|lb|abbr=on}}, averaging {{convert|1.5|kg|lb|abbr=on}}.<ref>[http://www.oriannesociety.org/eastern-indigo-snake Eastern Indigo Snake]. The Orianne Society. Retrieved 2012-11-30.</ref><ref>{{cite journal | vauthors = Hyslop NL, Cooper RJ, Meyers JM | year = 2009 | title = Seasonal shifts in shelter and microhabitat use of ''Drymarchon couperi'' (eastern indigo snake) in Georgia | journal = Copeia | volume = 2009 | issue = 3| pages = 458–464 | doi=10.1643/ch-07-171| bibcode = 2009Copei2009..458H | s2cid = 52462723 }}</ref> Specimens over {{convert|2.6|m|ft|abbr=on}} can weigh up to {{convert|5|kg|lb|abbr=on}}.<ref>Godwin, James C. [http://www.alaparc.org/Outreach/factsheets/Eastern%20Indigo%20Snake%20Fact%20Sheet.pdf Eastern Indigo Snake Fact Sheet]. alaparc.org</ref> Although the eastern indigo snake is similar in average body mass, extremely large specimens of the bulky, sympatric venomous eastern diamondback rattlesnake can outweigh it.<ref name = "Wood">{{cite book|author=Wood, Gerald|url=https://archive.org/details/guinnessbookofan00wood|title=The Guinness Book of Animal Facts and Feats|year=1983|publisher=Guinness Superlatives |isbn=978-0-85112-235-9|url-access=registration}}</ref>

==Geographic distribution== The eastern indigo snake inhabits areas from Florida to the southern areas of Georgia and Alabama.<ref>{{Cite web |title=Eastern Indigo Snake (''Drymarchon couperi)'' {{!}} U.S. Fish & Wildlife Service |url=https://www.fws.gov/species/eastern-indigo-snake-drymarchon-couperi |access-date=2025-04-24 |website=www.fws.gov |language=en}}</ref> Studies in Georgia showed that the most indigo snake sightings happen within the Tufton Upland region of the Coastal Plain especially in the sand ridges. <ref>Stevenson, D. J., Dyer, K. J., & Willis-Stevenson, B. A. (2003). Survey and monitoring of the eastern indigo snake in Georgia. Southeastern Naturalist, 2(3), 393–408. https://doi.org/10.1656/1528-7092(2003)002[0393:SAMOTE]2.0.CO;2 </ref>Their historic range extended into Louisiana, Mississippi, and South Carolina.<ref name=iucn/> A related species, the Texas indigo snake ''(Drymarchon melanurus erebennus)'', is found in southern Texas and Mexico.<ref name=r11/> <!-- Deleted image removed: right| '''Drymarchon couperi''' climbing -->

==Conservation status== Because of habitat loss, the eastern indigo snake is listed as a federally threatened species in Georgia and Florida.<ref name="uga.edu">Grosse, Andrew M. (J.D. Willson, editor). [http://srelherp.uga.edu/snakes/drycou.htm Eastern Indigo Snake (''Drymarchon couperi'' )] {{Webarchive|url=https://web.archive.org/web/20210530173844/https://srelherp.uga.edu/snakes/drycou.htm |date=30 May 2021 }} Savannah River Ecology Laboratory, University of Georgia.</ref> In 2012 the Alabama Department of Conservation and Natural Resources had listed the species as possibly extirpated within the state.<ref name="outdooralabama">{{cite web |url=http://www.dcnr.state.al.us/watchable-wildlife/what/Reptiles/Snakes/ |title=Snakes in Alabama |work=Outdoor Alabama |publisher=Alabama Department of Conservation and Natural Resources |access-date=6 June 2012 |archive-url=https://web.archive.org/web/20120527200626/http://www.dcnr.state.al.us/watchable-wildlife/what/Reptiles/Snakes/ |archive-date=27 May 2012}}</ref> A reintroduction program has shown initial signs of success, with an individual sighted in March 2022.<ref>{{cite web |url=https://www.cnn.com/2022/03/20/us/rare-snake-alabama-trnd/index.html |title=Rare snake found in Alabama for just the second time in 60 years |website=CNN |date=20 March 2022 |access-date=21 March 2022}}</ref>

The eastern indigo snake was largely eliminated from northern Florida due to habitat loss and fragmentation. A restoration program is currently underway at Apalachicola Bluffs and Ravines Preserve (ABRP) in northern Florida. It was last observed at ABRP in 1982, until 2017, when 12 snakes were released as part of the program. Twenty more snakes were released in 2018, with another 15 (10 females and five males) in 2019. The 10-year program is a collaborative effort between the Florida Fish and Wildlife Conservation Commission and private partners.<ref>{{Cite news|url=https://content.govdelivery.com/accounts/FLFFWCC/bulletins/200a57e|title=Good news for a big snake: 20 eastern indigo snakes just released to begin year two of the north Florida recovery|work=Florida Fish & Wildlife Conservation Commission|access-date=2018-07-23|language=en}}</ref>

NatureServe considers the species to be "endangered".<ref>{{cite web |title=NatureServe Explorer 2.0 |url=https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.102208/Drymarchon_couperi |website=explorer.natureserve.org |access-date=28 August 2025}}</ref>

Another issue facing the species is infections due to the snake fungal disease caused by ''Ophidiomyces ophiodiicola''.<ref name="ReferenceA">{{Cite journal |last1=Chandler |first1=Houston C. |last2=Allender |first2=Matthew C. |last3=Stegenga |first3=Benjamin S. |last4=Haynes |first4=Ellen |last5=Ospina |first5=Emilie |last6=Stevenson |first6=Dirk J. |date=2019-06-12 |title=Ophidiomycosis prevalence in Georgia's Eastern Indigo Snake (''Drymarchon couperi)'' populations |journal=PLOS ONE |language=en |volume=14 |issue=6 |article-number=e0218351 |doi=10.1371/journal.pone.0218351 |issn=1932-6203 |pmc=6561582 |pmid=31188875 |bibcode=2019PLoSO..1418351C |doi-access=free }}</ref> This fungus infects the dermal layer of snake skin, causing a variety of lesions that commonly manifest on the head and near the vent.<ref name="ReferenceA"/>

Captive eastern indigo snake populations also are affected by ''Cryptosporidium serpentis''. This protozoal parasite causes gastric cryptosporidiosis inside the snake's body, which leads to reduced water and nutrient intake. This causes illness in most and even death in some. If the snake is infected, it may display clinical signs such as dehydration, regurgitation, and weight loss.<ref>{{cite journal |last1=Hawthorne|first1=William Hansen|last2=Bogan Jr.|first2=James E.|last3=Goessling|first3=Jeffery M. |date=June 2024|title=Physiological Responses of Eastern Indigo Snakes (''Drymarchon couperi)'' Infected with ''Cryptosporidium serpentis ''. |url= https://doi-org.easydb.angelo.edu/10.5818/JHMS-D-22-00016|journal=Journal of Herpetological Medicine and Surgery|volume=34|issue=2|pages=137–144| doi=10.5818/JHMS-D-22-00016|access-date=2024-11-06|url-access=subscription}}</ref>

==Preferred habitat== The eastern indigo snake frequents flatwoods, hammocks, dry glades, stream bottoms, cane fields, riparian thickets, and high ground with well-drained, sandy soils.<ref name=r11/> In Georgia, the eit prefers excessively drained, deep, sandy soils along major streams, as well as xeric sandridge habitats.<ref name=r1/><ref>{{cite web |url=https://www.northwestwildlife.com/learn/species-reports/tiger-salamander/ |title=Tiger Salamander |website=northwestwildlife.com |access-date=2022-06-25}}</ref> The species is also strongly associated with longleaf pine and scrub oak communities which usually have turkey oak, live oak, and sand post oak trees.<ref>Stevenson, D. J., Dyer, K. J., & Willis-Stevenson, B. A. (2003). Survey and monitoring of the eastern indigo snake in Georgia. Southeastern Naturalist, 2(3), 393–408. https://doi.org/10.1656/1528-7092(2003)002[0393:SAMOTE]2.0.CO;2</ref> Georgia, they occur in the middle and lower coastal plain. <ref>[https://www.jstor.org/stable/1563828]</ref> In the northern parts of its range it is restricted to sandhills and requires gopher tortoise burrows during colder seasons.<ref>{{cite journal |last1=Breiniger |first1=David |title=Factors Influencing Home-Range Sizes of Eastern Indigo Snakes in Central Florida |journal=Journal of Herpetology |year=2011 |volume= 45 |issue=4 |pages=484–90 |doi=10.1670/10-176.1 |s2cid=86159497 |url=https://doi.org/10.1670/10-176.1.|url-access=subscription }}</ref> Xeric slash pine plantations seem to be preferred over undisturbed longleaf pine habitats.<ref name=r6/> Habitat selection varies seasonally. From December to April, eastern indigo snakes prefer sandhill habitats; from May to July, the 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.<ref name=r9/> In a study in Georgia, winter sightings generally occurred on sandhills, in association with gopher tortoise (''Gopherus polyphemus'') burrows.<ref name=r1/> These burrows can be used as cover from predators, fires, or extreme temperatures that may come through the area.<ref>{{Cite journal |last1=Hyslop |first1=Natalie L. |last2=Meyers |first2=J. Michael |last3=Cooper |first3=Robert J. |last4=Stevenson |first4=Dirk J. |date=2014 |title=Effects of Body Size and Sex of ''Drymarchon couperi'' (Eastern Indigo Snake) on Habitat Use, Movements, and Home Range Size in Georgia |journal=The Journal of Wildlife Management |volume=78 |issue=1 |pages=101–111 |doi=10.1002/jwmg.645 |jstor=43188431 |bibcode=2014JWMan..78..101H |issn=0022-541X}}</ref> In these sandhill environments, foraging, nesting, ecdysis, and potentially mating occur at or in these burrows. <ref>{https://link.springer.com/article/10.1007/s10144-011-0292-3}</ref>

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-scrub oak (''Pinus elliottii''), pine flatwoods, and pine-mesic hardwoods.<ref name=r1/>

==Cover requirements== Because the cover requirements of the eastern indigo snake 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.<ref name=r9/> In winter, the eastern indigo snake dens in gopher tortoise burrows, which are usually found in open pine forests with dense herbaceous understories.<ref name=r6/> These gopher tortoise burrows are used for nesting, foraging, and shelter before the snakes shed.<ref>Diemer, J. E., & Speake, D. W. (1983). The distribution of the eastern indigo snake, Drymarchon corais couperi, in Georgia. Journal of Herpetology, 17(3), 256–264. https://doi.org/10.2307/1563828</ref> Burrows need to be in areas with no flooding. The eastern indigo snake heavily uses debris piles left from site-preparation operations on tree plantations.<ref name=r6/> These piles are often destroyed for cosmetic reasons, but should be left intact because they provide important cover for both the snake and its prey. Summer home ranges for the eastern indigo snake can be as large as {{convert|273|acre|ha|abbr=off}}.<ref name=r9>Speake, Dan W.; McGlincy, Joe A.; Colvin, Thagard R. (1978). "Ecology and management of the Eastern Indigo Snake in Georgia: a progress report". pp. 64–73. '''''In'':''' Odum RR, Landers L (editors). (1978). ''Proceedings, Rare and Endangered Wildlife Symposium. Tech. Bull. WL4.'' Atlanta, Georgia: Georgia Department of Natural Resources, Game and Fish Division.</ref>

==Food habits and behavior== The eastern indigo snake is carnivorous, like all snakes, and consumes any other small animal it can overpower. It has been known to kill some of its prey by pressing the prey against nearby burrow walls.<ref>{{Cite web |date=2016-04-25 |title=Eastern indigo snake |url=https://nationalzoo.si.edu/animals/eastern-indigo-snake |access-date=2022-04-26 |website=Smithsonian's National Zoo |language=en}}</ref> They will stick their heads into stump holes or burrows, patrolling fringes of wetlands, or potentially climbing after prey.<ref>[https://bioone.org/journals/southeastern-naturalist/volume-9/issue-1/058.009.0101/Prey-Records-for-the-Eastern-Indigo-Snake-Drymarchon-couperi/10.1656/058.009.0101.short]</ref> Captive specimens are frequently fed dead items to prevent injury to the snake from this violent method of subduing its prey. Chemosensory studies with mice (''Mus musculus'') have shown that ''D. couperi'' responds with significantly elevated rates of tongue flicking and investigation towards visual cues of prey, and not volatile chemical cues.<ref>{{cite journal|vauthors=Saviola AJ, Lamoreaux WE, Opferman R, Chiszar D|year=2011|title=Chemosensory response of the threatened eastern indigo snake (''Drymarchon couperi'' ) to chemical and visual stimuli|journal=Herpetological Conservation and Biology|volume=6|issue=3|pages=449–454|url= http://herpconbio.org/Volume_6/Issue_3/Saviola_etal_2011.pdf}}</ref> They are diurnal, terrestrial snakes that are regarded as wide-ranging, active foragers.<ref>[https://bioone.org/journals/southeastern-naturalist/volume-9/issue-1/058.009.0101/Prey-Records-for-the-Eastern-Indigo-Snake-Drymarchon-couperi/10.1656/058.009.0101.short]</ref> 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. The eastern indigo snake also eats slugs,<ref>Prey Records for the Eastern Indigo Snake</ref> turtles, lizards, frogs, toads, fish, a variety of small birds and mammals, and eggs.<ref name=r11>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. Boston: Houghton Mifflin Company.</ref><ref name=r6>{{cite journal | author = Landers J. Larry | author2 = Speake, Dan W. | year = 1980 | title = Management needs of sandhill reptiles in southern Georgia | journal = Proceedings, Annual Conference of Southeast Association Fish & Wildlife Agencies | volume = 34 | pages = 515–529 }}</ref><ref>{{cite web | url=https://animaldiversity.org/accounts/Drymarchon_couperi/ | title=''Drymarchon couperi'' (Eastern Indigo Snake) | website=Animal Diversity Web }}</ref>

As defensive behavior, the eastern indigo snake vertically flattens its neck, hisses, and vibrates its tail. If picked up, it seldom bites.<ref>Conant, Roger (1975). ''A Field Guide to Reptiles and Amphibians of Eastern and Central North America, Second Edition.'' Boston: Houghton Mifflin. xviii + 429 pp. + Plates 1–48. (''Drymarchon corais couperi'', pp. 186–187 + Plate 27 + Map 144).</ref>

It often cohabits with gopher tortoises in their burrows, although it will settle for armadillo holes, hollow logs, and debris piles when gopher tortoise burrows cannot be found. Hunters, hoping to flush out rattlesnakes, often accidentally kill 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.{{citation needed|date=January 2019}}

==Predators== As an apex predator, the eastern indigo snake has few natural predators. Instead, humans represent the biggest threat. Highway fatalities, wanton killings, and over-collection for the pet trade adversely affect snake populations. Snakes are taken illegally from the wild for the pet trade. The eastern indigo snake is sometimes "gassed" in its burrow by rattlesnake hunters.<ref name=r1>{{cite journal|author=Diemer, Joan E.|author2=Speake, Dan W.|year= 1983|jstor=1563828 |title=The distribution of the Eastern Indigo Snake, ''Drymarchon corais couperi'', in Georgia|journal=Journal of Herpetology|volume= 17|issue=3|pages= 256–264|doi=10.2307/1563828}}</ref> Along with increasing infrastructure and the pet trade, eastern indigo snake populations are drastically declining due to habitat fragmentation. The eastern indigo snake's decline is correlated with the gopher tortoise's decline as well. since the eastern indigo snake utilizes the gopher tortoise's burrows for brumation.

In Florida, the eastern indigo snake may be eaten by some growth stages of invasive snakes such as the Burmese python, reticulated python, Southern African rock python, Central African rock python, boa constrictor, yellow anaconda, Bolivian anaconda, dark-spotted anaconda, and green anaconda.<ref>{{Cite book|title=Final Environmental Assessment For The Large Constrictor Snakes Listed As Injurious Wildlife under the Lacey Act|date=January 2012|publisher=U.S. Fish and Wildlife Service}}</ref>

==Reproduction== The eastern indigo snake is oviparous.<ref>Schmidt, Karl P.; Davis, D. Dwight (1941). ''Field Book of Snakes of the United States and Canada''. New York: G.P. Putnam's Sons. 365 pp. (''Drymarchon corais couperi'', pp. 133–135, Figure 32 + Plate 14).</ref> Its eggs are {{convert|75|–|100|mm|in|frac=4|abbr=on}} long by {{convert|27|–|32|mm|in|frac=4}} wide. The female lays a single clutch of 4–14 eggs from late April through early June.<ref>{{cite journal |last1=Stevenson |first1=Dirk |title=Nesting Sites of the Eastern Indigo Snake (''Drymarchon couperi)'' in Georgia |journal=Southeastern Naturalist |year=2021 |volume=20 |issue=2 |pages=345–52 |doi=10.1656/058.020.0212 |s2cid=236288532 |url=https://doi.org/10.1656/058.020.0212.|url-access=subscription }}</ref> The hatchlings are {{convert|600|–|700|mm|in|frac=4}} long.<ref>Wright, Albert Hazen; Wright, Anna Allen (1957). ''Handbook of Snakes of the United States and Canada''. Ithaca and London: Comstock Publishing Associates, a division of Cornell University Press. 1,105 pp. (in two volumes). (''Drymarchon corais couperi'', pp. 200–203, Figures 20 & 64, Map 21).</ref> The eastern indigo snake is often referred to as a late maturing colubrid; it usually does not reach maturity until it is 3–5 years old and around 5–6 feet in length. The female eastern indigo snakes has the ability to retain live sperm for long periods, potentially over 4 years. Thus, the female is able to choose when to release the sperm to fertilize the eggs.<ref>{{Cite web |title=The Eastern Indigo Snake |url=https://www.oriannesociety.org/about/the-eastern-indigo-snake/ |access-date=2022-04-05 |website=The Orianne Society |language=en-US |archive-date=26 August 2021 |archive-url=https://web.archive.org/web/20210826013300/https://www.oriannesociety.org/about/the-eastern-indigo-snake/ }}</ref> Mating season is at a peak from November to January but can occur from October through March.<ref>{{Cite web |title=Species Profile: Eastern Indigo Snake (Drymarchon couperi) {{!}} SREL Herpetology |url=https://srelherp.uga.edu/snakes/drycou.htm |access-date=2022-04-05 |website=srelherp.uga.edu}}</ref> This occurs while the snakes are in their sandhill habitats. <ref>[https://link.springer.com/article/10.1007/s10144-011-0292-3]</ref>

===Captivity and care=== Due to its generally docile nature and appearance, some people find the eastern indigo snake to be 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.

A study by Emily C. Lynch aimed to determine the ideal conditions for Indigo Snakes kept in captivity found that snakes with access to florescent light and unchanging behavioral enrichment items had the lowest stress levels and maintained the highest activity levels. Snakes that had rotating enrichment items had higher stress levels than those with unchanging environments. Snakes kept in these conditions took less time to emerge from their hide, spent more time basking, and had lower levels of stress hormones in their feces.<ref>Lynch, E. C., Roznik, E. A., Smith, D., Alvey, A., Giammona, F., Brown, J. L., Boisseau, N., Williams, A., Barr, M., Allen, N., & Hagen, K. (2025). The effects of light and novel enrichment on Eastern indigo snake (Drymarchon couperi) behavior and physiology. Applied Animal Behaviour Science, 286, 106598. https://doi.org/10.1016/j.applanim.2025.106598 </ref>

One notable owner of a pet eastern indigo snake was gonzo journalist Hunter S. Thompson during the time he wrote his ''Hell's Angels'' book. One evening, about 1966<!-- maybe 1967; terminus ante quem is Cardinal Spellman's death in December 1967 -->, he left his snake — with a mouse to eat — in a cardboard box in the Random House editor's office, but the mouse gnawed through the box and both animals escaped. The snake was subsequently beaten to death by the night watchman, which still caused Thompson great anguish several years later, and was his justification for sending his — often excessive — room service bills to Random House.<ref>Thompson, H.S. (1973). ''Fear and Loathing: On the Campaign Trail '72''. San Francisco: Straight Arrow Books. 506 pp. {{ISBN|978-0-87932-053-9}}.</ref>

==Sources== {{USDA|article=Drymarchon couperi |url=http://www.fs.fed.us/database/feis/animals/reptile/drco/all.html}}

==References== {{Reflist}}

==Further reading== *Conant, Roger; Bridges, William (1939). ''What Snake Is That?: A Field Guide to the Snakes of the United States East of the Rocky Mountains''. (With 108 drawings by Edmond Malnate). New York and London: D. Appleton-Century Company. Frontispiece map + 163 pp. + Plates A–C, 1–32. (''Drymarchon corais couperi'', pp.&nbsp;63–65 + Plate 10, figure 27). *Goin, Coleman J.; Goin, Olive B.; Zug, George R. (1978). ''Introduction to Herpetology, Third Edition''. San Francisco: W.H. Freeman. xi + 378 pp. {{ISBN|0-7167-0020-4}}. (''Drymarchon corais'', p.&nbsp;117; ''Drymarchon corais couperi'', pp.&nbsp;124, 308, Figure 16–1). *Holbrook JE (1842). ''North American Herpetology; or, A Description of the Reptiles Inhabiting the United States. Vol. III.'' Philadelphia: J. Dobson. 122 pp. (''Coluber couperi'', new species, pp.&nbsp;75–77 & Plate 16). *Morris, Percy A. (1948). ''Boy's Book of Snakes: How to Recognize and Understand Them''. (A volume of the Humanizing Science Series, edited by Jaques Cattell). New York: Ronald Press. viii + 185 pp. (''Drymarchon corais couperi'', pp.&nbsp;34–36, 179). *Powell R, Conant R, Collins JT (2016). ''Peterson Field Guide to Reptiles and Amphibians of Eastern and Central North America, Fourth Edition''. Boston and New York: Houghton Mifflin Harcourt. xiv + 494 pp., 47 plates, 207 Figures. {{ISBN|978-0-544-12997-9}}. (''Drymarchon couperi'', p.&nbsp;373 + Plate 33 + Figure 158). *Smith, Hobart M.; Brodie, Edmund D. Jr. (1982). ''Reptiles of North America: A Guide to Field Identification''. New York: Golden Press. 240 pp. {{ISBN|0-307-13666-3}} (paperback), {{ISBN|0-307-47009-1}} (hard cover). (''Drymarchon corais couperi'', pp.&nbsp;188–189). *Zim HS, Smith HM (1956). ''Reptiles and Amphibians: A Guide to Familiar American Species: A Golden Nature Guide''. New York: Simon and Schuster. 160 pp. (''Drymarchon corais'', pp.&nbsp;94, 156).

==External links== *[https://web.archive.org/web/20080623223118/http://fwie.fw.vt.edu/WWW/esis/lists/e154009.htm Conservation Management Institute: Eastern Indigo Snake] *[http://www.britannica.com/eb/article?tocId=9042323 Encyclopædia Britannica Online: Indigo Snake] *[https://ecos.fws.gov/ServCat/DownloadFile/157073: 2018 Species Status Assessment Report (pdf)]

{{Taxonbar|from=Q2710665}} {{Authority control}}

{{DEFAULTSORT:Eastern Indigo Snake}} Category:Drymarchon Category:Snakes of North America Category:Reptiles of the United States Category:Fauna of the Eastern United States Category:Taxa named by John Edwards Holbrook Category:Reptiles described in 1842 Category:Apex predators