Eastern indigo snake: Drymarchon corais couperi
Genus/Species: Drymarchon corais
Subspecies: Drymarchon corais couperi
Common Name: Eastern indigo snake
Federal Status: Threatened
FL Status: Federally-designated Threatened
FNAI Ranks: G4T3/S3 (Globally: Apparently Secure, Sub sp. Rare/State: Rare)
IUCN Status: LC (Least Concern)
The Eastern indigo snake is a non-venomous, bluish-black colored snake that can reach lengths of eight feet (2.4 meters). Its chin, cheek, and throat are mostly red or brown, but can also be white or black. Most indigo snakes have smooth scales, although adults do have keels (ridges) on the front of some of their scales (Florida Natural Areas Inventory 2001). When approached, the Eastern indigo snake shows no aggression (L. Nester pers. comm. 2011). They are also exothermic species – their body temperature is externally regulated.
The Eastern indigo snake’s diet primarily consists of a variety of species, including small mammals, birds, toads, frogs, turtles and their eggs, lizards, and small alligators (National Park Service, n.d.).
Indigo snakes begin breeding between the months of November and April and nest between the months of May and August. Females lay 4-12 eggs yearly or bi-yearly, with the eggs hatching 90 days after being laid. Since the indigo snake is a commensal of the gopher tortoise, females usually deposit their eggs in gopher tortoise burrows. Females may have the ability to hold sperm, which would allow them to defer fertilization of an egg. Parthenogenesis (a form of asexual reproduction) may also be possible with Eastern indigo snakes, as some virginal snakes have been seen laying eggs (Kendrick and Mengak 2010, Smithsonian Marine Station at Fort Pierce, n.d.).
Habitat and Distribution
Eastern indigo snakes inhabit pine flatwoods, hardwood forests, moist hammocks, and areas that surround cypress swamps. They can be found throughout Peninsular Florida and southeastern Georgia (Florida Museum of Natural History, n.d.).
The main threats facing the Eastern indigo snake is habitat destruction, fragmentation, and degradation. Habitat destruction is caused mainly by the extension of urban development in their habitat. Indigo snakes lose more than 5% of their habitat each year in Florida (Kendrick and Mengak 2010). As a species that often occupies gopher tortoise burrows, indigo snakes face being injured by people hunting for rattlesnakes in the burrows. This action usually causes death to other species in the burrow including Easter indigo snakes. Habitat degradation is also a result from this action. Habitat fragmentation is also a threat as increased housing and road development can separate their habitat into smaller individual habitats. Small fragmented habitats can have problems supporting a viable population. Other threats include pollutants, vehicle strikes, captures for domestication, and intentional killings (Kendrick and Mengak 2010, Florida Natural Areas Inventory 2001).
Conservation and Management
The Eastern indigo snake is protected as a Threatened species by the Federal Endangered Species Act and as a Federally-designated Threatened species by Florida’s Endangered and Threatened Species Rule .
Federal Recovery Plan
Federal Action Plan
Other Informative Links
Species Profile: Eastern Indigo Snake
Florida Museum of Natural History
Florida Natural Areas Inventory
International Union for Conservation of Nature
National Park Service
Smithsonian Marine Station at Fort Pierce
University of Georgia - Featured Herp in the Big Cypress National Preserve
University of Georgia - Eastern Indigo Publication
U.S. Army Environmental Command
U.S. Fish and Wildlife Service
Printable version of this page
Florida Museum of Natural History. (n.d.). Eastern indigo snake, indigo snake, racer. Retrieved May 23, 2011, from Herpetology: http://www.flmnh.ufl.edu/herpetology/fl-guide/Drymarchoncouperi.htm
Florida Natural Areas Inventory. 2001. Field guide to the rare animals of Florida. http://www.fnai.org/fieldguide/pdf/drymarchon_couperi.pdf
Kendrick, M. M., & Mengak, M. T. (2010, September). Eastern Indigo Snake (Drymarchon couperi). Retrieved May 23, 2011, from The Warnell School of Forestry and Natural Resources
National Park Service. (n.d.). Eastern Indigo Snake: Species Profile. Retrieved May 23, 2011, from Everglades National Park: http://www.nps.gov/ever/naturescience/easternindigosnake.htm
Smithsonian Marine Station at Fort Pierce. (n.d.). Drymarchon couperi. Retrieved May 23, 2011, from North American Mammals: http://www.sms.si.edu/irlspec/drymar_couper.htm
Image Credit Photo by FWC