Brazilian Rainbow Boas, Epicrates cenchria cenchria are the most commonly kept and bred of the Epicrates cenchria subspecies. The other subspecies include the Colombian Rainbow Boa, Epicrates cenchria maurus, and the Argentinian Rainbow boa, Epicrates cenchria alvarezi which are both bred in fair numbers by breeders here in the United States. The Peruvian Rainbow boa, Epicrates cenchria gaigei and the Isla Marajo Rainbow Boa, Epicrates cenchria barbouri are bred in very limited numbers and are not often available here in the U.S. The three or four other recognized subspecies of Rainbow Boas are nearly nonexistent in U. S. collections and information about them is limited. The taxonomy of Epicrates cenchria is subject to considerable disagreement and the designation of the different subspecies will likely change in the future. Other snakes within the Epicrates genus include the insular Cuban, Haitian, Peurto Rican, Jamaican, Turks and Caicos, Berry Island and Bimini Boas. Some of these insular Epicrates are occasionally incorrectly called "Rainbow Boas".
The Brazilian, Peruvian and Isla Marajo subspecies of Epicrates cenchria are all brightly colored (usually some shade from red to orange to mahogany brown) and very handsomely marked with a dark ring pattern down the back. They have dark spots along the sides these spots often have bright light colored crescents above them. There is a great deal of variation in color and marking among these three subspecies but the Peruvian and Isla Marajo specimens are often marked with heavier and darker ring and spot markings. The Peruvian subspecies is also reported to be slightly larger than the other two. The Peruvian Rainbows also have fewer and larger scales than Brazilian Rainbows. I suspect that Isla Marajo Rainbows also have fewer and larger scales but I have no reliable information to support this. Some sources describe the Peruvian subspecies as having the highlighted crescents on the sides forming complete rings. Most Peruvian Rainbows do not have these crescents forming complete circles and the complete circles do occur on a very few Brazilian Rainbows. There is enough variation in these three subspecies that descimination of subspecies usually requires scale counting.
The Colombian Rainbow Boas are smaller than Brazilians and as adults are a uniform brown color with a faint ring and spot pattern showing through. This is especially noticeable in bright light. All of the Rainbow Boas are very iridescent and will display a vivid prismatic rainbow effect in sunlight or artificial light produced at wavelengths near natural sunlight. Colombian Rainbow neonates are husky and marked like poorly colored Brazilians. They are very easy to keep and breed. Colombian Rainbows require high humidity but not nearly as high as that required by Brazilian Rainbows.
The Argentinian subspecies are still smaller than the Colombians and are also much more slender. They are marked with a fairly intricate ring and spot pattern but are usually colored various shades of gray to tan and brown. Some specimens will have an orangish wash to their color. Neonates of this subspecies are much smaller than the previous two subspecies and are fairly delicate in comparison. My Argentinian Rainbows breed only every other year. Argentinian Rainbows do not need very high humidity or very high temperatures.
There are Rainbow Boas from Guyana which are marked like they may be a possible intergrade between Brazilian and Colombian Rainbows. When they are available as captive born babies or wild caught imports they are usually labeled as Guyanan Rainbows and often have the scientific name Epicrates cenchria crassus attached to them by breeders and importers. Most published sources describe crassus as coming from south of the Amazon basin. I have bred this subspecies in the past and found them to be easy to care for and breed though they are smaller than Colombian Rainbows and the babies are born fairly small and can be difficult to get started feeding on pink mice.
Brazilian Rainbow Boas occur naturally across much of the northern half of South America. They were exported in fair numbers from Surinam during the eighties and early nineties. They are now exported in much more limited numbers and most specimens offered for sale today are captive bred. Limited numbers of Brazilian Rainbow Boas have been exported out of Peru. These Brazilian Rainbows are reported to reach larger sizes than Brazilian Rainbow Boas from the rest of their range.
Baby Brazilian Rainbows are born in litters of two to thirty five. A typical litter contains twelve to twenty five babies. The babies are usually fifteen to twenty inches long and are usually born looking robust and healthy. Most specimens start out striking at anything that moves but can be tamed with regular calm handling. They need to be kept at temperatures near 80 degrees and in high humidity. Temperatures above 85 degrees can cause fatalities in Brazilian Rainbows. They will do well kept individually in plastic shoeboxes until they are about 24 inches long and can then be moved into larger plastic storage containers or box type cages. They should not be kept in fish tanks or similar cages as the large screened area will allow too much humidity to escape from the cage. As adults they will usually drink large amounts of water and will not require nearly as high relative humidity in their cages. Babies should be fed on a schedule of from once every four days to once a week. Most of them will continue to feed even when they are opaque prior to shedding. Many people make the mistake of feeding pinky mice to baby Brazilian Rainbow Boas. If you have an unlimited source of pinky mice then go ahead and feed them to baby Brazilian Rainbows but be prepared to feed lots of them at each feeding. These snakes are born large enough to take hopper mice as their first meal. Many of mine have done well starting out on rat pinkys. A mouse pinky will make a very small lump in a baby Brazilian Rainbow and be digested down so that the lump is no longer externally visible within 24 hours. They will grow rapidly on one or two appropriately sized mice a week. Yearlings often grow to 48 inches in length though 36 to 40 inches is more typical. Many two-year-olds are four and a half to five feet long. Female seem to eat more and grow larger than males. Adult males can do well on 20 medium sized rats per year.
Brazilian Rainbow Boas are difficult to sex based on visible external differences until they are about three years old. Young ones can be sexed by probing. Females will probe a distance of two to four subcaudal scales and males will probe to a depth of eight to twelve subcaudal scales. Adult males have substantially larger spurs along the side of the vent and also have noticeably thicker bases of their tails due to the invaginated hemipenes. After about eight years of age the heads of both sexes are noticably larger than on nearly similar sized young adults. This phenomena of the enlarged head on older animals seems to be more pronounced on red and orange animals than on brownish specimens. This phenomena also occurs with older Peruvian Rainbows.
Brazilian Rainbows can be bred at two and a half years of age if the females are large enough and have enough weight. A female should be at least five feet long and weigh over three pounds. Another six inches of length and pound of weight is more appropriate and should produce a larger first litter with less strain on the mother snake. Standard boid cooling seems to be necessary to allow the formation of egg and sperm cells. Brazilian Rainbow Boas will usually begin breeding within a few weeks of being warmed back up after the cooling period. Females will show a very marked mid body ovulatory lump for several hours. This lump is usually not seen because it lasts for such a short time. Most gravid females will refuse to feed. They will sometimes take a very small prey animal while they are gravid. Many females will become enormously large in the back half of their body and look very emaciated in the front half late in the gestation. Reproduction takes an extreme amount of energy and should only be attempted with very healthy adults. Gestation lasts approximately five months. The female will often appear restless and cruise around the cage as if looking for something for a day or two before laying. Laying often occurs during weather changes. Female snakes should not be disturbed while they are laying as this may cause them to interrupt oviposition which can lead to incidences of stillborn babies. Females often eat recently laid infertile slugs. I have never witnessed a female eating babies but recognize that the possibility exists for a snake which is picking through a pile of live babies and slugs to possible devour a newborn baby accidentally. For this reason I try to remove the babies from the mother soon after they are born. Many babies will strike at anything that moves. They can be tamed fairly quickly by handling them gently and regularly over the first few weeks. They will often eat before they have shed. The first shed usually occurs after 10 to 14 days from birth. Shedding should occur about once a month while they are growing and then occur about every other month. I feed babies fairly often and they seem to convert food into linear growth without becoming obese. Later in life feeding too heavily can lead to an unhealthy overweight condition.
Thanks to Jeff Clark for the care sheet.