Robert Harper’s Rainbow Boa Care Sheet I’ve kept rainbow boas off and on for about 15 years. They were one of my first reptilian loves and the first species of snake that I bred in captivity. Rainbow boas make excellent pets and are not any more difficult to keep than a boa constrictor as long as you keep in mind that they cannot get too hot and that they need to have access to areas of high humidity. Size Rainbow boas are born approximately 12-16” long (depending on subspecies) and will grow to between 4-7’ as adults with 5-6’ being average for adult Brazilian rainbow boas. In my experience, females grow larger on average than males. Temperament Baby rainbow boas can be quite nippy, but they quickly calm down with regular handling. Adults that are regularly handled are typically very tame. Housing Baby rainbow boas can be housed comfortably in a 10 gallon aquarium or comparably sized enclosure providing that it has a secure lid (they are very good at escaping). Alternatively, they can be kept in appropriately sized plastic “shoeboxes” or sweater boxes until subadults. The size of the enclosure should increase with the size of the boa. Adults are best housed in cages that are 4’ x 2’ x 1.5’, though a cage that is 3’ x 2’ will suffice for a single adult. I recommend housing them individually, but I and several others I know have successfully maintained several adult rainbow boas in the same cage without incident. Males should not be housed together, though, since they may fight. A variety of substrates can be used with rainbow boas. Options include newsprint, aspen shavings, Care fresh, paper towels, and cypress mulch. Cypress mulch is a fantastic substrate as it holds humidity very well, but it isn’t too available in some places and care must be taken when feeding boas so that it isn’t ingested. Care fresh is available at many pet stores, smells clean, holds humidity decently well if misted, and doesn’t mold as quickly as aspen shavings. I use it for baby as well as adult rainbow boas. If newsprint is used, a humid hide box should definitely be provided. Regardless of the substrate used, it should be kept clean and free of mold. Temperature & Humidity A temperature gradient is very important. Temperatures on the cool side of the enclosure can get down around 75 degrees; ambient temperatures on the warm side can be up to 85 degrees. Heating of the enclosure can be accomplished with a heat pad, heat tape, or basking lamp on one side of the enclosure. The key is that the snake be able to escape the heat if it needs to. Heaters should be controlled with a reliable dimmer switch, rheostat, or thermostat (the best option is a proportional thermostat). Several suitable thermostats are commercially available. I like the Herpstat from Spyder Robotics personally. Night time temperatures can safely drop into the 70s. Humidity is also very important for rainbow boas. I’ve heard several people say that rainbow boas need humidity as high as 90 percent to do well, but that has not been my experience. I have found that a relative humidity of around 70 percent is sufficient for baby boas (with a slight increase during shed cycles), while even lower overall relative humidity can be sufficient for adults provided a humid hide box is provided. Such high humidity can be maintained by daily misting and the presence of a large water bowl in most cases. If an enclosure with a screen top is used, ½ to ¾ of the screen can be covered to reduce moisture loss. I provide a plastic box with an entrance hole that is filed with moist sphagnum moss for my juvenile and adult rainbow boas to retreat to. Note that humid does not equal damp. The cage and substrate should not always feel wet to the touch. A perpetually wet cage will grow mold and fungus and spell health problems for your captives. If you mist your enclosures, the substrate should not be wet within a few hours. If it stays wet all the time, reduce the amount of misting or increase the ventilation in the cage. While too much ventilation will make the cage dry out quickly, too little is worse. What you really want to avoid is humidity that is too high and temperatures that are too low; this can rapidly lead to a respiratory infection. Feeding Baby rainbow boas can eat an appropriately sized food item every 3-7 days. I typically start mine on fuzzy/hopper mice and move up from there. Adults will take medium to large rats every 7-14 days. One of the great things about Brazilian rainbow boas is that it is rare to find a problem feeder. Breeding males and females may refuse food; this is normal. Rainbow boas can easily be trained to accept pre-killed or thawed rodents, which I highly recommend. A medium adult rat can inflict a serious bite on a snake if it has the opportunity. How I Keep Juveniles I have personally used a variety of approaches to keep rainbow boas successfully. The following is the way I currently raise rainbow boas and the method with which I have had the most success. I keep baby rainbow boas in a “snake rack” where each individual baby is housed separately in a small plastic “shoebox” (usually a 4-6qt Sterilite container or other similar plastic box). It is imperative that this box have a tight fitting lid and be escape proof. I drill several small holes in the sides of the box for ventilation. These holes must be small enough so that the baby cannot fit through them; about 1/8” in diameter should be okay, or whatever looks good. You don’t want to drill a ton of holes, just enough to get decent air exchange. For very young rainbow boas I use paper towels as the substrate and I include a small container full of dampened sphagnum moss and a decent sized ceramic water dish (ramekins are cheap and work well too). You may also include another “hide” spot. Little plastic or ceramic dishes made to hold flower pots with a hole knocked out work great. My snake rack is basically a shelf system that these boxes fit into with some 3” wide heat tape wired across the back of every shelf to provide heat. It is important, though, that if you use a heat source that you attach it either to a rheostat (dimmer) or thermostat to prevent overheating. Baby rainbows tolerate temperatures between 75-85 degrees; hotter than 85 degrees can be deadly. During the summer my snake room stays around 80 degrees along the wall where I keep my rainbow boas, so I just turn the supplemental heat off. If you have a similar location that stays warm, you might find that the supplemental heat is unnecessary, but you need to measure the temperature (don’t guess). You can usually pick up a digital min/max thermometer at the hardware store for about $10, and I highly recommend using one to monitor cage temperatures. Once a day I lightly mist the tub, check the water, and replace the paper towel if it is soiled. I try to feed defrosted rodents to all of my snakes because it is cheaper, more convenient, and safer since it removes the possibility of the snake getting bitten by its intended prey and eliminates the possibility of transmitting parasites. Rainbow boas will usually start on thawed (or “f/t” if you’re a herper) food without any problems. I generally thaw out the food item, place it in a plastic bag and float it in hot water to heat it up, and lay it on the floor of the enclosure (or on a piece of paper plate if you are using something other than paper towels as a substrate). Baby rainbow boas will eat fuzzy or small hopper mice and will graduate to larger items as the y grow. If you are purchasing a baby rainbow boa from me, it is feeding on f/t food already unless otherwise specified. I keep rainbow boas in a similar fashion for about the first two years of their lives except that as they grow I move them over to a different substrate (shavings or care fresh) and into larger, appropriately sized boxes. My adults live in 3ft or 4ft long cages. I am a particular fan of Vision cages due to their light weight and ease of cleaning and viewing.