| Eastern indigo snake | |
|---|---|
| Conservation status | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | Squamata |
| Family: | Colubridae |
| Subfamily: | Colubrinae |
| Genus: | Drymarchon |
| Species: | Drymarchon couperi |
| Binomial name | |
| Drymarchon couperi (Holbrook, 1842) |
|
| Synonyms | |
The eastern indigo snake (Drymarchon couperi) is a large nonvenomous snake with an even blue-black coloration, with some specimens having a reddish-orange to tan color on the throat, cheek and chin. This smooth- scaled snake is considered to be the largest native snake species in the United States with the longest recorded specimen measuring 9.2 feet (2.8 m). The eastern indigo snake received its name from the glossy iridescent blackish-purple sheen it displays in bright light.
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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. Eastern indigo snakes have a number of common names including indigo, blue indigo snake, black snake, blue gopher snake, and blue bull snake.
The eastern indigo snake ranges from southern South Carolina south through Florida and west to Louisiana, Mississippi, and Alabama.[1] The Texas indigo snake (subspecies Drymarchon melanurus erebennus) is found in southern Texas and Mexico.[2]
Because of habitat loss, the eastern indigo snake is listed as a federally threatened species in Georgia and Florida.[3]
Eastern indigo snakes frequent flatwoods, hammocks, dry glades, stream bottoms, cane fields, riparian thickets, and high ground with well-drained, sandy soils.[2] In Georgia, snakes prefer excessively drained, deep sandy soils along major streams, as well as xeric sandridge habitats.[4] Xeric slash pine plantations seem to be preferred over undisturbed longleaf pine habitats.[5] 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.[6]
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 virgianiana), 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.[4]
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.[6] In winter, indigo snakes den in gopher tortoise burrows, which are usually found in open pine forests with dense herbaceous understories.[5] 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.[5] 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).[6]
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.[2][5]
As defensive behavior the eastern indigo snake vertically flattens its neck, hisses, and vibrates its tail. If picked up, it seldom bites.[7]
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.
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.[4]
Eastern indigo snakes are oviparous.[8] 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.[9]
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.
This article incorporates public domain material from the United States Department of Agriculture document "Drymarchon corais".