Environmental & Extension Services Department - Natural Resources Division
Florida Eastern Indigo Snake (Drymarchon corais couperi)
Description: The
Eastern indigo snake is the longest non-venomous snake in North America. Adults
are typically between 5 and 7 feet long, but can reach a length of over 8 feet.
They are an iridescent, glossy, blue-black and may have a red or cream patch on
their throat or the side of their head. In the Florida Keys, individuals often
lack the red or cream coloration. Hatchlings are similar to the adults, but may
have white bands around their body. In captivity, they have lived as long as 25
years, but longevity information is not available for wild individuals. Eastern
indigos are sometimes confused with black racers. Black racers, however, are
rarely longer than 4 feet, are thinner, and are a dull black with white or brown
throats.
Status: Eastern indigo snakes are protected by The United States Fish and Wildlife Service (FWS) and the Florida Fish and Wildlife Conservation Commission (FWC) under the Endangered Species Act and Chapter 39, Florida Administrative Code, respectively. The Eastern indigo snake has been listed as Threatened since 1971 by the state of Florida and since 1978 by the FWS. This protection makes it illegal to possess, harm, or harass Eastern indigo snakes.
Range: Historically, the range of the Eastern indigo snake included the coastal plain of the southeastern United States, from South Carolina through Florida. Currently, most Eastern indigo snakes are found in Florida and southern Georgia. Recently, it has been reintroduced in several locations in Alabama and Mississippi.
Habitat: The Eastern indigo snake can be found in a variety of upland and wetland vegetation communities. In Charlotte County, they can be found in pine flatwoods, oak hammocks, scrub, and along fresh water marshes and riverine systems. In extreme southern Florida, Eastern indigos are found in hardwood hammocks, fresh water marshes, and mangrove swamps. In north and central Florida, indigo snakes are found primarily in dry vegetation communities including scrub and pine flatwoods, where they utilize gopher tortoise burrows. Although gopher tortoise burrows are used throughout their range, they are especially important in northern Florida where they are used by the indigo snake to keep warm during the winter, and to keep cool and prevent dehydration in the summer. In wetter areas, and those that lack gopher tortoise burrows, indigo snakes use armadillo holes, hollow logs, or other holes for dens. Areas that have been cleared, including agricultural areas, are sometimes used by the indigo snake, as long as debris piles are available. Home range size is highly variable and depends on the sex of the animal and the time of year. Adult males generally have home ranges that are several times larger than females and juveniles. The home range of adult males in south Florida averages 180 acres and can be up to 470 acres, while adult females usually have home ranges of 45 acres and up to 120 acres. Home ranges generally are largest during the summer and shrink in size during the winter, as their activity level decreases.
Diet: Eastern indigo snakes commonly eat frogs, toads, salamanders, birds, small mammals and other snakes. Juveniles most commonly eat invertebrates. Indigo snakes generally hunt along the ground during the day. Wetlands and gopher tortoise burrows are important hunting grounds.
Indigo snakes do not constrict or use poison to kill their prey. Instead, they immobilize their prey by pressing it against the ground and swallowing it alive.
Reproduction and Hatchlings: Eastern indigo snakes reach sexual maturity at 3 to 4 years of age. In South Florida, breeding occurs from June to January. An average of 9 eggs is laid in animal burrows or in fallen logs from April through July. Hatchlings, measuring 1½ to 2 feet long, emerge from their eggs after approximately 90 days. They grow quickly, attaining a length of 5 feet in 3 years.
Threats: The Eastern indigo snake requires large amounts of undeveloped land. Currently, the largest threat to the Eastern indigo snake is loss of habitat due to construction of buildings and roads. As development increases, habitats become fragmented and can lead to the isolation of populations or leave individuals without mates. Vehicles hit and kill Eastern indigo snakes as they cross roads within their home ranges or as they warm themselves on the pavement. Other detrimental effects associated with development include an increase in the amount of pesticides used by land owners and an increase of pets. Pesticides can accumulate in their tissues and cause ulcers, reproductive failure, and even death. Free-ranging or feral cats and dogs harass or even kill indigo snakes and other species of wildlife. Historically, indigo snakes were commonly killed during rattlesnake roundups, when rattlesnakes were collected from burrows and holes after gasoline was poured in burrows. This method of snake collection is now illegal in Florida, but may still occur. Indigo snakes were once heavily collected for the pet trade because of their beauty and docile temperament in captivity. It is now illegal to keep indigo snakes without a permit.
What You Can Do to Help: Watch out for Eastern indigo snakes and other wildlife while you are driving. Do not kill snakes and other wildlife indiscriminately. Few snakes in Florida are venomous and all are beneficial, by eating animals that people often perceive as pests. Keep cats and dogs from roaming, since they may harass or even kill Eastern indigo snakes. Limit the use of pesticides around your house to help Eastern indigos and other wildlife. Keeping Eastern indigo snakes as pets is illegal unless you have a permit. Continue to read about Eastern indigo snakes and other wildlife at the library or on the Internet. Suggested Internet sites include: http://endangered.fws.gov/I/C1Q.html.
Selected References:
Ahston, R.E. and P.A. Ashton. 1988. Eastern Indigo Snake. Pages 65- 67 in Handbook of Reptile and Amphibians of Florida, Part One: The Snakes. Winward Publishing Inc., Miami.
Moler, P.A. 1992. Eastern Indigo Snake. Pages 181-186 in Rare and Endangered Biota of Florida, Volume III. Amphibians and Reptiles. University Press of Florida, Gainesville.
Charlotte County Natural Resources
743-1239
7/99 (updated 2/01)
For more information
Charlotte County Environmental & Extension Services
25550 Harbor View Road, Unit 2, Port Charlotte, FL 33980
941.764.4360
