Index of Species Information
WILDLIFE SPECIES: Drymarchon couperi
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| Eastern indigo snake. U.S. Army, Creative Commons image. |
Introductory
WILDLIFE SPECIES: Drymarchon couperi
AUTHORSHIP AND CITATION :
Snyder, S. A. 1993. Drymarchon couperi. In: Fire Effects Information System, [Online].
U.S. Department of Agriculture, Forest Service,
Rocky Mountain Research Station, Fire Sciences Laboratory (Producer).
Available: www.fs.usda.gov/database/feis/animals/reptile/drco/all.html [].
Revisions :
On 23 Ocotber 2015, the common and scientific names of this species were changed
from: indigo snake, Drymarchon corais
to: eastern indigo snake, Drymarchon couperi.
Citations were added [15,16] to support the changes.
ABBREVIATION :
DRCO
COMMON NAMES :
indigo snake
American corais snake
blue bull snake
blue gopher snake
Couper's snake
Georgia snake
TAXONOMY :
The currently accepted scientific name for the eastern indigo snake is
Drymarchon couperi (Holbrook) (Colubridae) [15,16].
The Texas indigo snake a separate species (Drymarchon melanurus) [16] and
is not covered in this review.
ORDER :
Squamata
CLASS :
Reptile
SYNONYMS :
Drymarchon corais (Holbrook)[11,14]
Drymarchon corais corais (Boie) [14]
Drymarchon corais couperi (Holbrook)[11]
FEDERAL LEGAL STATUS :
The eastern indigo snake is federally listed as Threatened [13].
OTHER STATUS :
The eastern indigo snake is in decline throughout its range [9,17].
The state of Florida lists it as threatened [12].
WILDLIFE DISTRIBUTION AND OCCURRENCE
WILDLIFE SPECIES: Drymarchon couperi
GENERAL DISTRIBUTION :
The eastern indigo snake ranges from southern South Carolina south
through Florida and west to Mississippi [11, 17].
ECOSYSTEMS :
FRES12 Longleaf-slash pine
FRES13 Loblolly-shortleaf pine
FRES16 Oak-gum-cypress
FRES41 Wet grasslands
STATES :
BLM PHYSIOGRAPHIC REGIONS :
None
KUCHLER PLANT ASSOCIATIONS :
K079 Palmetto prairie
K080 Marl - everglades
K091 Cypress savanna
K092 Everglades
K112 Southern mixed forest
K113 Southern floodplain forest
K115 Sand pine scrub
K116 Subtropical pine forest
SAF COVER TYPES :
70 Longleaf pine
71 Longleaf pine - scrub oak
72 Southern scrub oak
81 Loblolly pine
82 Loblolly pine - hardwood
84 Slash pine
85 Slash pine - hardwood
89 Live oak
104 Sweetbay - swamp tupelo - redbay
105 Tropical hardwoods
111 South Florida slash pine
241 Western live oak
SRM (RANGELAND) COVER TYPES :
808 Sand pine scrub
810 Longleaf pine-turkey oak hills
811 South FLorida flatwoods
812 North Florida flatwoods
813 Cutthroat seeps
814 Cabbage palm flatwoods
815 Upland hardwood hammocks
816 Cabbage palm hammocks
817 Oak hammocks
820 Everglades flatwoods
821 Pitcher plant bogs
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| Longleaf pine woodland, an eastern indigo snake habitat. Photo by Chuck Bargeron, University of Georgia, Bugwood.org. |
PLANT COMMUNITIES :
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 [1].
BIOLOGICAL DATA AND HABITAT REQUIREMENTS
WILDLIFE SPECIES: Drymarchon couperi
TIMING OF MAJOR LIFE HISTORY EVENTS :
Eastern indigo snakes can grow as long as 125 inches (262 cm). They mate from
November through March with a peak in mid-November through late
December. The age of sexual maturity is unknown [9]. An average of 3
to 10 eggs are laid in March through July; eggs hatch from May through
October [10]. The average life span of the eastern indigo snake is 11 years,
although they can live as long as 21 years [11]. They do not hibernate
and remain somewhat active during winter, especially if temperatures are
higher than 50 degrees Fahrenheit (10 deg C) [9].
PREFERRED HABITAT :
Eastern indigo snakes frequent flatwoods, hammocks, dry glades, stream bottoms,
cane fields, riparian thickets, and high ground with well-drained, sandy
soils [11]. In Georgia, snakes prefer excessively drained, deep sandy
soils along major streams, as well as xeric sandridge habitats [1].
Xeric slash pine plantations seem to be preferred over undisturbed
longleaf pine habitats [6]. 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 [9].
COVER REQUIREMENTS :
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 [9]. In winter eastern indigo snakes den in
gopher tortoise burrows, which are usually found in open pine forests
with dense herbaceous understories [6]. Burrows need to be in areas
where there is no flooding. Eastern indigo snakes also heavily use debris piles
left from site-preparation operations on tree plantations [6]. 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 eastern indigo snake can be as large as 273
acres (229 ha) [9].
FOOD HABITS :
Eastern indigo snakes eat other snakes, turtles, lizards, frogs, toads, a
variety of small birds and mammals, and eggs [6,11].
PREDATORS :
Humans represent the biggest threat to eastern indigo snakes. Highway
fatalities, wanton killings, and overcollection for the pet trade
adversely affect eastern indigo snake populations. Snakes are taken illegally
from the wild and sold as petsi. Snakes are also inadvertantly gassed in
their burrows by rattlesnake hunters [1].
MANAGEMENT CONSIDERATIONS :
Eastern indigo snakes are a commensal species associated with gopher tortoises.
Snakes use abandoned tortoise burrows heavily in the winter and spring
[1]. For this reason it is necessary to maintain healthy tortoise
populations, also a species in decline throughout its range. Because
slash piles are used by snakes for hiding and foraging, this debris
should be left intact on pine plantations [6]. Speake and others [9]
recommend protecting several thousand hectares of prime eastern indigo snake
habitat to ensure the snakes' year-round needs are met. Some important
sandhill communities of Georgia and Florida are being replaced by slash
pine plantations, which can support a few snakes if burned and planted
with wide spacing to encourage gopher tortoise populations [6].
Recommendations for captive breeding of eastern indigo snakes are as follows
[10]: Captive snakes should be released to the wild after 2 to 3 years,
and new snakes from the wild should be introduced to the captive
population, preferably every winter. This is important because wild
snakes seem to grow faster and produce more young than snakes held in
captivity. Because smaller snakes do not use tortoise burrows, they
should be released in wetland areas with plenty of herbaceous cover near
the water's edge. Hatchlings will den in areas with dense saw palmetto
(Serenoa repens) and should be released near these areas.
FIRE EFFECTS AND USE
WILDLIFE SPECIES: Drymarchon couperi
DIRECT FIRE EFFECTS ON ANIMALS :
Because hatchlings do not use tortoise burrows they may be susceptible
to fire mortality. However, adult snakes may be able to escape fires
while in their burrows [10].
HABITAT RELATED FIRE EFFECTS :
Fire exclusion in southern pine-scrub oak habitats is a major cause of
habitat degredation for gopher tortoise and, therefore, eastern indigo snakes
[6]. The absence of fire allows oaks to mature and leaf litter to
accumulate, making burrow digging difficult and herbaceous food scarce.
Studies of herpetofauna in Florida sandhill commmunities showed higher
species diversity in young sand pine (Pinus clausa)-scrub oak habitats,
which are maintained by frequent fire [7]. Experimental burns in these
communities showed snakes used plots burned at 2- and 7-year intervals
more than plots left unburned or burned yearly. The effects of
different season burns on gopher tortoises in Ocala National Forest,
Florida, showed more burrows in July-burned areas than in
February-burned areas at the first postfire year [8]. Preburn densities
of gopher tortoise were not determined.
FIRE USE :
Landers and Speake [6] recommend burning eastern indigo snake habitats every 2
years to maintain a young, open overstory and an abundant herbaceous
understory. This will provide good gopher tortoise habitat, which in
turn will provide burrows for snakes. Burning sandhill communities
every 2 to 4 years will maintain open longleaf pine stands with
understories of wiregrass (Aristida stricta) and turkey oak [6].
Burning in late summer where young eastern indigo snakes have been released from
captive breeding programs is not recommended because young snakes depend
on dense herbaceous vegetation for cover instead of burrows [10].
FIRE REGIMES :
Find fire regime information for the plant communities in which this
species may occur by entering the species name in the FEIS home page under
"Find Fire Regimes".
REFERENCES
WILDLIFE SPECIES: Drymarchon couperi
REFERENCES :
1. 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. [21093]
2. Eyre, F. H., ed. 1980. Forest cover types of the United States and
Canada. Washington, DC: Society of American Foresters. 148 p. [905]
3. Garrison, George A.; Bjugstad, Ardell J.; Duncan, Don A.; [and others].
1977. Vegetation and environmental features of forest and range
ecosystems. Agric. Handb. 475. Washington, DC: U.S. Department of
Agriculture, Forest Service. 68 p. [998]
4. Kuchler, A. W. 1964. Manual to accompany the map of potential vegetation
of the conterminous United States. Special Publication No. 36. New York:
American Geographical Society. 77 p. [1384]
5. Landers, J. Larry. 1987. Prescribed burning for managing wildlife in
southeastern pine forests. In: Dickson, James G.; Maughan, O. Eugene,
eds. Managing southern forests for wildlife and fish: a proceedings;
[Date of conference unknown]; [Location of conference unknown]. Gen.
Tech. Rep. SO-65. New Orleans, LA: U.S. Department of Agriculture,
Forest Service, Southern Forest Experiment Station: 19-27. [11562]
6. 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. [21092]
7. Mushinsky, Henry R. 1985. Fire and the Florida sandhill herpetofaunal
community: with special attention to responses of Cnemidophorus
sexlineatus. Herpetologica. 41(3): 333-342. [11953]
8. Robbins, Louise E.; Myers, Ronald L. 1992. Seasonal effects of
prescribed burning in Florida: a review. Misc. Publ. No. 8. Tallahassee,
FL: Tall Timbers Research, Inc. 96 p. [21094]
9. 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. [21090]
10. Speake, Dan; McGlincy, Donna; Smith, Cynthia. 1987. Captive breeding and
experimental reintroduction of the eastern indigo snake. In:
Proceedings, 3rd Southeast nongame and endangered wildlife symposium:
84-88. [21091]
11. Conant, Roger; Collins, Joseph T. 1991. A field guide to reptiles and
amphibians: Eastern and central North America. 3rd ed. Peterson Field
Guide Series No. 12. Boston: Houghton Mifflin Company. 450 p. [22902]
12. Wood, Don A., compiler. 1994. Official lists of endangered & potentially
endangered fauna and flora in Florida. Tallahassee, FL: Florida Game and
Fresh Water Fish Commission. 22 p. [24196]
13. U.S. Department of the Interior, Fish and Wildlife Service. 2016.
Endangered Species Program, [Online]. Available: http://www.fws.gov/endangered/.
[86564]
14. ITIS Database. 2015. Integrated taxonomic information system, [Online].
Available: http://www.itis.gov/index.html. [51763]
15. Collins, Joseph T. 1991. Viewpoint: a new taxonomic arrangement for some
North American amphibians and reptiles. Herpetological Review.
22(2): 42-43. [89439]
16. Crother, Brian I., Chair. 2012. Scientific and standard English names
of amphibians and reptiles of North America north of Mexico, with
comments regarding confidence in our understanding. Herptelogical Circular
No. 39. Shoreview, MN: Society for the Study of Amphibians and Reptiles.
92 p. [88775]
17. NatureServe. 2017. NatureServe Explorer: An online encyclopedia of life,
[Online]. Version 7.1. Arlington, VA: NatureServe (Producer). Available:
http://www.natureserve.org/explorer. [69873]
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