Reptiles
Indigo Snake
Drymarchon · also called indigo snake
An indigo snake is a big, calm, blue-black hunter that turns the usual snake fear on its head: landowners in the southeastern US are glad to have one, because it kills and eats rattlesnakes. The eastern indigo is the longest snake native to the country, it needs the burrows of gopher tortoises to survive, and its gentleness once nearly wiped it out.
Overview
Indigo snakes are the genus Drymarchon, large non-venomous snakes ranging from the southeastern United States to Argentina. They are generalist predators — rodents, birds, frogs, turtles, small alligators, and other snakes — and are resistant to pit viper venom, so they routinely eat rattlesnakes, cottonmouths, and copperheads. Despite their size they do not constrict; they overpower prey with their jaws and swallow it alive.
The eastern indigo
The eastern indigo snake reaches 2.4 m, occasionally near 2.8, making it the longest US native snake. It is active by day, ranges over hundreds of hectares, and depends on gopher tortoise burrows for shelter from cold, heat, fire, and drought — it cannot persist where the tortoise is gone. In good light its scales flash iridescent blue-purple.
Too gentle for its own good
Eastern indigos are famously docile, rarely biting even when caught. That, plus their size and colour, drove heavy collection for the pet trade and sideshows, which helped crash wild numbers before protection.
Status
Least Concern across the genus, but the eastern indigo is Threatened under US law — hit by habitat loss, the gopher tortoise’s decline, road deaths, and past over-collection. Captive breeding and reintroduction are now returning it to protected sites in Alabama and Florida.
Indigo Snake: common questions
Is the indigo snake venomous or dangerous?
No. The indigo snake has no venom and is not a constrictor, and it is one of the most even-tempered large snakes in the Americas, with a strong reputation for not biting even when handled. It poses no threat to people or pets, beyond the fact that a very large one could take a small chicken. In fact the eastern indigo is often welcomed by landowners because it kills and eats venomous snakes, including rattlesnakes and cottonmouths, to which it is largely immune.
How does an indigo snake kill a rattlesnake?
Directly and quickly. The indigo snake seizes the rattlesnake, usually near the head, in its jaws, then chews forward to get a firm grip while thrashing and beating the rattlesnake against the ground. It has partial immunity to pit viper venom, so a defensive bite from the rattlesnake does little harm, and it simply overpowers the prey and swallows it, often while it is still alive and moving. Kingsnakes kill rattlesnakes by constriction; the indigo relies on size, strength, and venom resistance instead.
Why does the eastern indigo snake need gopher tortoises?
In the dry, sandy, fire-swept pine habitats where the eastern indigo lives, there is little natural shelter from cold snaps, summer heat, drought, and wildfire, and the deep burrows dug by gopher tortoises provide all of it. Indigo snakes use tortoise burrows as refuges year-round and especially as overwintering dens in the northern part of the range. Where gopher tortoises have been removed, poisoned, or lost to disease and development, indigo snakes disappear too, which is why protecting the two species is linked.
Can you keep an indigo snake as a pet?
In the United States the eastern indigo snake is federally protected, so keeping one requires permits and captive-bred, properly documented animals, and casual pet keeping is not allowed. Some non-US indigo and closely related cribo snakes are kept by experienced hobbyists. Even setting the law aside, an indigo is a demanding pet. It grows very large, is extremely active and needs a big enclosure, and has a fast metabolism, a large appetite, and waste to match. Their docility is appealing, but they are not a beginner or casual snake.