The eastern indigo snake (Drymarchon couperi) is revered for its alert and intense nature, intelligence, and fearless but genuinely friendly temperament. It is considered by many to be the jewel of the reptile world and has a well-earned reputation as the one snake species that will form an obvious bond to its owner. Listed as a threatened species and protected by the Endangered Species Act, it is illegal to take eastern indigos from the wild. In nature, they are found in Alabama, Georgia, and Florida. Captive-bred specimens are legal to keep and breed in most states, but check your local laws first.
Adults can be kept individually in conventional, front-opening cages or in sliding trays or rack systems. Adult enclosures should have 6 to 8 square feet of floor area and between 8 inches and 24 inches of vertical height. Use absorbent bedding, consisting of a mixture of wood shavings and pelletized wood pulp or paper pulp. Indigo snakes require a continuous source of water. A water bowl that is 6 inches across but isn’t quite large enough for the animal to soak in is preferred. During non-breeding periods of the year, one end of the cage should be warmed to 82 to 84 degrees for 12 hours each day using under-cage heating. The cool side should be in the mid to high 70s. At night, when the heating is turned off, the room temperature should not drop below 70 degrees. Keep humidity between 50 and 70 percent. The eastern indigo snake is considered a winter breeder, meaning that in the wild, it will most often copulate between October and January. In reality, males will attempt copulation with any ovulating female they encounter, no matter the time of year. When a female eastern indigo ovulates, she produces a pheromone that is released from her skin. This pheromone creates a track along the ground wherever she moves. Male eastern indigos are so sensitive to this scent that they can locate an ovulating female from a great distance. So, the first priority in getting eastern indigos to breed is getting the females to ovulate. About 12 years ago, in early July, I noticed that every time I entered my snake room, all three of my adult males were at the front of their cages, moving continuously back and forth. The females did not move in their cages at all. I suspected that the males wanted to mate, but July was just too early. After three weeks of watching this, I gave in and put one adult female into each cage. I suspected that the males would aggressively try to mate, but instead they showed no interest in the females.I initially assumed that restless behavior in snakes was due to other causes. After years of breeding experience, I confirmed my early suspicions were correct. When eastern indigos pace their cages, it typically stems from one of four reasons: recent defecation (they dislike the smell of their feces), temperatures being too warm, females seeking moist spots for egg-laying, or males wanting to mate. In one instance, only males were restless for weeks, ruling out the first three explanations. The cause was a female in the room ovulating, but I hadn’t introduced the right female to the males’ cages!
To initiate mating, the author places males and females together at day’s end, turns off room heaters, and keeps windows closed. I’ve found that female eastern indigo ovulation is triggered by decreasing day length in fall and winter. In their native southeastern U.S., ovulation usually happens in October. In captivity, artificial night lighting can disrupt this seasonal cue. Breeders must expose snakes to natural daylight cycles—about 15 hours of light in summer and 11 hours in mid-winter—for success. In my case, a new female from an artificially lit environment had her seasonal balance upset; moving her to natural lighting caused ovulation. Since then, I’ve never seen restless males in July. Indigo Snake Cooling And Breeding: Many colubrid breeders brumate snakes in winter by lowering ambient temperatures to 45–55°F for 2–4 months without feeding. Spring warming then triggers breeding. However, eastern indigos aren’t spring breeders; they use gopher tortoise burrows for protection, with winter underground temperatures not dropping below 65°F. Their dark pigmentation helps them warm in morning sun to reach comfort in the low 80s on most winter days. Thus, many breeders cool them only at night to the mid-60s and warm them daily to year-round daytime temperatures. Egg bump: I wondered if nighttime cooling was crucial for eastern indigo breeding. After a successful 2005 hatch, I experimented the next season.During one breeding season, I turned off heaters at night but kept windows closed, maintaining temperatures above 75°F. Daytime temperatures were raised to 82°F, as is typical in winter. Mating was successful, and by January, eggs were palpable in females. After egg laying in March, nearly 200 eggs were obtained from 16 females, but most were infertile. By the end of July, only 31 hatchlings remained.
Two years later, I experimented with lower nighttime temperatures by removing window screens and using a fan to blow air out, achieving lows of 55°F during mating season. Daytime temperatures were kept in the low 80s. The following July, 91 hatchlings resulted from just 10 females, yielding the best per-female success rate ever. I interpret these observations as indicating that day length primarily affects female fertility, while temperature is key for male fertility. Low nighttime temperatures may be crucial for proper sperm development in males, though explicit evidence is still lacking. These findings suggest that male eastern indigo snakes in the wild do not spend nights underground during mating season. Transponder studies show males travel long distances to find females, while females stay in small home ranges. Females likely use burrows to avoid cold nights, whereas males are exposed to lower temperatures above ground. I start nighttime cooling in mid-September or earlier, allowing at least six weeks before the first matings. Productive matings can occur from October ovulation until at least February end, and I have successfully paired single males with up to four females during this period. For feeding and breeding, the presence of ovulated females inhibits the male’s feeding response, a protective mechanism to prevent mistaking females for food. To maintain energy for mating with multiple females, males must eat regularly. Using a neutral enclosure for mating prevents scent tracks from disrupting the male’s feeding, as placing females in the male’s cage could cause him to stop eating entirely.Adult eastern indigos typically reach between 5.5 and 7 feet in length. It is recommended to wait until they reach 5 feet long and 5 years of age before breeding them.
When ready to initiate mating, place the male and female together at the end of the day. Shut off the room heaters but keep the windows closed. Use a mating enclosure that is 5 feet in length by 1.5 feet wide but only 5 to 6 inches in vertical height, containing the same bedding used for the cages. As the mating environment cools slowly, the male will usually have a strong desire to copulate. A temperature of 76 degrees Fahrenheit is ideal to initiate mating. Snakes mate by feel, not sight, and both the male and female must actively participate. The dark environment is beneficial because the visual stimulus of a larger male may induce a fear response in the female. If the temperature is too warm, or if the female is focusing on visual perceptions, she may refuse to be mated and attempt to slap the male in the face with her tail. This may also occur if the female has been recently mated, has never mated before, or has not ovulated yet. Getting slapped in the face is a serious turn-off for the male, and just a few slaps may end his desire. At 76 degrees, mating lasts about nine to 10 hours. Some breeders report durations of 24 hours or more, possibly due to unverified lock-up or multiple locking events. Once mated, females become resistant to further mating attempts for about six weeks, likely due to a copulatory plug. After this period, the female becomes receptive again. Females that mate successfully before mid-January lay eggs in March or early April. If the first successful mating occurs later, egg laying is delayed, with a minimum gestation period of two months. When matings finish in mid-January, terminate nighttime cooling until egg-laying is complete. Set the heated side of the females’ cages to 80 degrees. Gravid females may become uncomfortable above 80 degrees, so do not let the ambient temperature fall below 75 degrees when heating is off at night. Some females lose their appetite in late January or February, indicating the next shed will be the pre-lay shed. Females that mate successfully by mid-January are remarkably synchronized in their pre-lay shed timing. Conversely, if the male enters the female’s cage, her territorial instinct may cause her to attack and possibly kill the male. ROBERT BRUCEIt is critical to mark the exact date of this shed. The large majority of gravid females will lay their eggs between 15 and 20 days later. I continue to feed females up until 10 days past shed. This is essential because the lack of food during the weeks before egg laying is a primary cause of egg-binding in captive eastern indigos. I always have food items available that these snakes particularly like to eat. Eastern indigos find the scent of mouse or chicken much more attractive than the scent of rat. Knowing this helps me get a meal into them when they are reluctant to eat.
After 10 days past their pre-lay shed, I stop feeding females because traces of urine from a recent meal may be accidentally released onto the eggs during laying, and this will weaken the shells, causing molding and/or rupture. Three to four days before the female lays her eggs, she searches for a moist location. Her restless movement starts in the morning, and as the time of egg-laying nears, her motions appear more frantic and extend later into the day. As soon as her search starts, provide her with an egg box containing a moist sphagnum moss substrate. I use a translucent storage box with a floor space of 8 inches by 12 inches and 41⁄2 inches deep, with a hole cut in one end for entrance and exit. It is important to prevent the eggs from being laid on the cage floor because they will quickly dry out and will not be recoverable. The female will go in and out of her egg box dozens of times before finally laying. Egg laying normally begins during the night and each egg takes about 20 minutes to emerge. The female will appear to be in an almost-comatose state during this time. During egg laying, the slightest movement of the cage, and even peering into the eggbox at night with a flashlight, can cause the female to stop. I check the egg box in the morning from outside the cage. When I notice eggs visible against the dark sphagnum moss, I give the female until the middle of the day, and then I open the egg box and carefully palpate her to make sure she has laid all of her eggs. Healthy indigo females typically lay 10 to 14 eggs. The first and last eggs in a clutch are more likely to be misshapen, hardened or infertile, and these can cause egg binding. Fortunately, these infertile eggs are usually easy to manually express from the female, if this is done within the 24-hour window following the start of laying. During gestation, careless handling of a gravid female can damage the egg closest to the vent, causing it to harden. Hardened eggs are more difficult for the female to pass and can cause the entire clutch of remaining healthy eggs to become bound. As the newly laid eggs dry, the shells harden. Infertile eggs usually remain soft, wet and slimy. Eastern indigos can be kept together for the first two weeks after hatching, but then they should be transferred to individual cages to prevent cannibalism. Robert Bruce ROBERT BRUCE An indigo snake pipping.To incubate eastern indigo snake eggs, position the good eggs one-third of the way down into a 1:1 mixture by weight of vermiculite and water. Mark the top of each egg before transfer to place them into the vermiculite in the exact positions they were laid. Incubation takes about 105 days at 78 degrees with 100-percent humidity, and care should be taken to insulate the eggs from shock and vibration during this period.
After hatching, eastern indigos can be kept together for the first two weeks, then transferred to individual cages to prevent cannibalism. By this time, they will have completed their first shed. They possess an internal yolk sac that feeds them for at least a month post-hatching. Although some hatchlings eat right away after their first shed, it is easier to wait until they are 4 to 6 weeks old before offering food. Frequent handling during this period alleviates their natural fear of humans and helps them focus on food later. For the first several meals, offer frozen/thawed pinky mice with their heads crushed. Scenting the food with feeder goldfish can sometimes persuade a reluctant hatchling to eat. Successful captive breeding of the eastern indigo snake is achievable for anyone willing to put forth extra effort, patience, and attentiveness. The satisfaction of being part of a new generation is an experience all reptile-lovers should enjoy. Robert Bruce is a professional breeder of eastern indigo snakes, providing animals to individuals and institutions across the United States.