Eastern Indigo Snakes are one of the largest snakes in North America, reaching a maximum total length of 2.6 meters (8.58 feet). Most records of wild specimens measuring 2.4 m. (7.83 ft.) or longer have been from southern Florida. The species is fairly stout-bodied and sexually dimorphic in size, with males attaining greater lengths than females. Large males are typically 2.0 to 2.3 m. (6.67 to 7.5 ft.) and weigh 3.2 to 4.5 kilograms (7 to 10 pounds), while large females seldom exceed 2 m. (6.5 ft.) and weigh 1.8 to 2.7 kg. (4 to 6 lbs.).
Eastern Indigo Snakes are a uniform bluish or gunmetal black, both dorsally and ventrally. A wash of orange-red is often present on the chin, sides of the head and throat. There is variation in this trait, with some populations in northern Florida having black lip scales, a white patch in the center of the throat and lacking orange-red. The orange-red pigment is more prominent in male Eastern Indigos and may extend onto the belly of some south Florida snakes.
The common name for Eastern Indigo Snakes relates to the large, smooth scales of this species which appear iridescent purple in sunlight. Adult males have partial keels on the scales along the middle of the back. Hatchling Eastern Indigos may possess a faint pattern of cream speckling forming indistinct lateral bands.
The scientific name of the Eastern Indigo Snake, Drymarchon couperi, roughly translates to “Emperor of the Forest.” As one of the largest snakes in North America, this majestic nonvenomous animal truly lives up to its name. Despite its docile nature when handled by humans, the Eastern Indigo Snake is a top predator and an icon for conservation.
The Eastern Indigo Snake is a wide-ranging top predator that, pound for pound, can require as much room to roam as an African Lion. It also requires different overwintering and summer foraging habitat that can be separated by considerable distance, resulting in a great deal of travel. And travel means crossing roads.
Habitat loss and fragmentation are the most significant causes of Eastern Indigo Snake decline. The species requires large expanses of natural habitat for both overwintering and foraging. Due to the prevalence of private land and small parcel sizes, the southeastern Coastal Plain is a patchwork of different land uses with little continuity across the landscape. Specifically, urban and rural development, agriculture, roads, altered fire regimes, forestry and conversion to pine plantations have fragmented habitats resulting in negative impacts to Eastern Indigo Snakes.
In addition, the Eastern Indigo Snake is directly linked to another vulnerable species—the Gopher Tortoise. In the northern portion of its range, the Eastern Indigo Snake is dependent on Gopher Tortoise burrows for shelter in the winter. As suitable Gopher Tortoise habitat has declined, so have the tortoise populations and with it the Eastern Indigo Snake.