Bolivian Short-tailed Boa Husbandry

Scope

This article is intended to provide basic requirements for maintaining Bolivian Short-tailed Boa Husbandry in captivity.

These information below is provided given based on our own experiences and opinions.

Synonym

  • Boa constrictor amarali (STULL 1932)1

Conservation Status

  • CITES Appendix II2

Natural Distribution

  • South East Bolivia, Southern Brazil, and Northern Paraguay

Description

Bolivian Short-tailed Boas come in a variety of colors and patterns, and captive animals are often selectively bred for different traits. Selectively bred animals often exhibit aberrant patterns, with broken saddles or striped dorsal pattern. Others have extremely peaked dorsal patterns (saddles) or reduced saddles to the point where they appear as dotted markings. The background color of these boas can range from pastel, to very dark grey in appearance.

The southern range Bolivian Boas are often referred to as “Silver-back” Bolivians because of a group of animals that had been imported to the US from the Sao Paolo, Brazil. This group of animals had a silver/grey coloration, which made them instantly popular among boa keepers, and they adopted the “Silver back” name.


Length and weight

Bolivian Boas are short, stout boas compared to their larger counterparts from Guyana, Suriname, and Peru, which often attain lengths of 2.4-2.7 meters (8-9 ft.). Bolivian males are generally less than half the weight of females and are typically noticeably shorter. The table below provides an example of average length and weight for Bolivian Boas.

Type Length Weight
Males 1.4 – 1.5 meters (4.5-5 ft.) 1,800-2,000g (3.9 – 4.4 lbs.)
Females 1.5 – 1.8 meters (5-6 ft.) 4,000-6,800g (8.8 – 15 lbs.)

Diet

Bolivian Boas should be offered frozen thawed rats of appropriate size. Live rodents are not recommended unless necessary, and in our experience, there is no reason for Bolivians not to accept frozen thawed rodents. Even adults that have been raised on pre-killed or live rodents in general will readily accept frozen thawed.

During the breeding season (September to February in Canada) adults may voluntarily go off food. This is natural for adult boas, and keepers should not worry. We offer our adults food year-round, and if they don’t accept meals offered during the breeding season, we simply give them two weeks and try again. In our experience, even gravid (pregnant) females often accept food throughout their entire gestation. Males, however, can refuse food now and then, especially if they have been placed with a female for breeding. Below is a table that summarizes the size of boa to appropriate prey size. Again, keepers should select a size that is appropriate to their boa

Prey Size:
  Neonates Juveniles Sub-adults Adults
Size Pinkie rats (4-9g) Weaned Rats (33-49g) Small/medium rats (50-164g) Large rats (165-274g)

Note: Even our large adult males feed on medium rats

I have read older literature that implies that Bolivian Boas sometimes suffer from regurgitation problems if offered too large a meal, or if fed too often. This has led to hobbyists believing that Bolivians may be more sensitive than other boas. However, in our experience this belief is not specific to Bolivians. Any boa that is over fed or fed too large a prey item under less than ideal husbandry conditions is prone to regurgitation. We would offer a very simple piece of advice; don’t overfeed your boa, and always provide adequate heating and temperature for your animal, and they will thrive just as any other boa constrictor.

The table below offers a general guide for feeding frequency. Keepers should adjust feeding frequency to meet the needs of their own animals.

Feeding Frequency
  Neonates Sub-adults Adults
Frequency 7 days 10 days 21 days

Selecting an appropriate prey size is an important part of husbandry. With most boas, a good way to select an appropriate prey size is by using the diameter of the snake itself. Prey size is generally equal to the diameter of the boa’s widest body region. However, with Bolivians we don’t necessarily follow this rule, because Bolivians tend to be short stout boas, which are heavier in the mid-section than other Boa constrictor types. Let me give you some examples:

Example 1:
  • Let’s say that you have an adult female Bolivian that’s approximately 5.5 ft. in length and 12 lbs. At the thickest body region, this animal may be equal to the size of a jumbo rat. Does this mean you should feed a 1.7 meter (5.5 ft.) animal a jumbo rat? In our experience, the answer is no. A jumbo rat is too large for this animal and we find sticking to large rats with a feeding frequency of every 21 days will suffice.
Example 2:
  • Let’s use an example where you have a neonate Bolivian that is only three months old. Neonate Bolivians are born smaller than other Boa constrictors, averaging only 50 grams or so. Therefore, they require smaller prey sizes. Should you use a prey size equivalent to the diameter of the boa? In this case the answer is yes. Why? Because neonate Bolivians need enough nourishment not only to survive, but to gain mass to grow and thrive.

Hopefully this comparison makes sense, and you get a better understanding of how to appropriately select a prey size to feed your boa.


Housing Bolivian Boas

Properly housing Bolivian boas, like all boas, is important. Selecting an appropriate cage size and providing the correct temperatures, humidity and substrate all contribute to the success of keeping animals healthy. Regardless of the size and type of caging you choose, housing should provide enough heat and thermal gradient to achieve success. Fortunately, Bolivians can tolerate a wide range of temperatures, although neonates do require more specific care than adults.

There are many different housing options available on the market today including glass aquariums, wood (Melamine) cages, plastic (PVC) cages, and reptile racks used to house multiple animals in a single system. Each of the options have their pros and cons, however in recent years the PVC options have become popular because they’re easy to clean, they maintain temperature and humidity, and don’t rot over-time like the wooden cages are prone to under high-humidity.

Typical Materials used for Housing:
Material Description
PVC Cages Polyvinyl chloride (PVC) is very popular these days for reptile cages. The material is very light so assembled cages can be conveniently moved around if required. PVC is also fire resistant and easy to clean.
Industrial Melamine Melamine cages were a good option back in the early days of reptile husbandry. Most people tend to use PVC cages today, although melamine is still popular for reptile racks.
Polypropylene bins Clear Polypropylene bins is a material that is used for totes and storage bins. These are typically used in reptile-rack systems, economical, and easy to clean.
Polycarbonate bins Similar to Polypropylene, Polycarbonate bins are nearly transparent, providing a much better view of the animal. However, they’re more expensive.
Cage Size

Selecting an appropriate case size is relatively easy, provided you have the room. We generally house our neonate boas in Rubbermaid/Iris bins (see table below). Inexperienced keepers may view these bins as being small; however, most boas benefit from small, dark lit bins because they provide them more security. In the case of small boas such as neonates or even some sub-adults, small to medium bins work well.

For adult boas (especially large females), large cages at least 121 cm (48″) will provide an appropriate amount of room. Keepers with especially large females 1.8 meters (6 ft.) can opt for larger cages to provide extra living space.

The table below provides a minimum cage size for the Bolivians. In our experience, larger is better.

Note: Measurements are in Length x Width x Height

  Neonates Sub-adults Adults
Males Cages     91x60x76cm (34″x18″x7″) Cages 91x60x30cm (48″x24″x12″)
Females Cages 121x60x30cm (48″x24″x12″) Cages 182x60x30cm (72″x24″x12″)
Both Bins typically 30x20x16.5cm (12″8″6.5″)  –  –

Temperature

As mentioned earlier, Bolivians tend to be more forgiving than other Boas, especially when it comes to temperature. Adult Bolivians can tolerate much colder temperatures than other boas. This is especially important when it comes to times such as breeding trials, when keepers tend to cool their animals to induce them to breed.

I prefer to cool all our animals, regardless of their age and size. We choose this because, in the wild animals are subjected to the same temperature regimes regardless of their age. In some cases, one could argue that adult boas are purely terrestrial in nature and therefore may be subjected to different temperatures than that of neonate or younger animals that may be semi-arboreal (this is often the case for younger boa species, which attempt to achieve greater security by being elevated off the ground). However, we believe there is more benefit to all animals experiencing the same temperature changes throughout their lives.

Given the information above, we provide the following temperature requirements for Bolivian Boas:
Time of Day Temperature
Day time hot-spot 29-30.5 C (85-87 F)
Day Time High (ambient) 26-27.5 C (79-82 F)
Night time low (ambient) 23-25.5 C (74-78 F)

Maintaining a thermal gradient for boas is an important part of husbandry. This is the main reason for providing an ambient cage temperature and hot spot. When boas are provided a hot spot, they will generally move back and forth from this spot during a typical day. As an animal prefers warmer conditions (typically after ingesting a meal) they can bask in the “hot spot”. When cases are constructed with the heat source at one end of the cage, this creates a thermal gradient in the cage where the opposite end of the cage can be naturally cooler, allowing the animal to choose what temperature it would like to maintain.

Heating can be provided using ceramic heat emitters, heat lamps, radiant heat panels, under-cage heat pads, and the popular Heat-tape method (under-cage heat tape). We prefer to use heat tape because it’s economical and easy to use. However, if you house your boas in a room that is not heated to at least 24C (76F), you may struggle to maintain adequate ambient cage temperature. In this case, we would suggest using a Radiant Heat Panel (RHP). These panels are easy to use and produce more heat than heat tape.

Accurately Measuring Temperature

Measuring the temperature of the cage and animal itself is something new hobbyists often struggle with. Often relying on pet store stick-on thermometers that are inaccurate, and only provide the temperature of the surface to which they’re attached. It is recommended that keepers invest in a Temperature Gun. These are easily found in your local hardware store. Using a temperature gun is a much more accurate way of measuring the temperature of the hot spot in the cage, cool spot, and the boa’s physical body temperature. This is especially important for gravid females, or neonates.


Humidity

Humidity requirements for Bolivians are easily met by simply spraying the enclosure weekly with a water bottle. Spraying the substrate (more on substrate below) is generally the best method of maintaining humidity, especially for those substrates such as coca mulch, cypress mulch, or another substrate that has high absorbency. Humidity is especially important for neonate Bolivians because they can be more susceptible to dehydration than larger boas. All boas benefit from higher humidity when it comes to the shedding process, as the much-needed moisture will aid the boa in shedding a solid, one-piece shed. Failure to have enough moisture in the cage may lead to shedding problems, and animals may have difficulty shedding properly, resulting in manual removal of stuck shed.

Typical Humidity Regime:
Time of Day Relative Humidity (%RH)
Day time high (DTH) 65-75%
Night time low (NTL) 65%
Accurately Measuring Humidity

Accurately measuring humidity is challenging, especially given the plethora of “Humidity meters” on the market which are of low value. Pet stores often sell stick on hygrometers that are inaccurate. However, there are products on the market such as the EXTECH hygrometers that are much more accurate, and provide a reliable means of tacking humidity. we use the EXTECH Big-digit Hygro-thermometer for animals in our collection.

Substrate

There are several choices when it comes to substrate used for boas such as mulches including: cypress, coca (crushed or mulched), news-paper, and paper towel. We prefer to use coca mulch for sub-adults and adults, and a peat moss-coca mulch mixture for neonates. Both adults and neonates will benefit from a deep substrate. We prefer to provide at least 8 cm (3″) of substrate for adults and two inches for neonates. If you provide enough substrate for your boas, you’ll find that they often push themselves underneath the substrate.

The other added benefit of using a mulch substrate as opposed to news-paper or paper towel is that mulch substrate will hold humidity longer and more consistently than paper products. This  means that you’ll have to spray the enclosure less often as well.

The table below provides some suggestions for substrate suitable for Boas:

Type Pro’s Con’s
Coca mulch (crushed or mulched) Holds moisture well, resistant to mold, aesthetically pleasing More expensive than alternatives, not always easy to obtain
Cypress mulch Holds moisture well, easy to obtain Not resistant to mold
News paper Economical, convenient: delivered to your front door, easy to replace Not aesthetically pleasing
Paper towel Economical, easy to replace Not aesthetically pleasing, only suited for neonates
Aspen Economical Doesn’t hold moisture well, molds easily

Lighting

Bolivians do not have strict lighting requirements; a simple 12-hour light period is sufficient. During the winter months when animals are cycling for breeding, lighting is reduced to imitate the shorter days


Cleaning

Maintenance of the cage is a daily, weekly, and monthly affair.

Water bowls:
  • Daily water bowls are visually inspected and disinfected/replaced when polluted with substrate or fecal matter using an appropriate disinfectant (see more on disinfectants below).
  • It’s also recommended to replace water each time an animal has defecated in the cage weather the water appears to be polluted or not. The water may have been contaminated in the process and it may not be visual to the keeper.
  • Otherwise, water bowls are disinfected and replaced once weekly.
Spot cleaning:
  • Spot cleaning is also a daily task. Any fecal material found in the cage is removed and disposed. Any substrate that is polluted by fecal material is discarded as well.
Substrate replacement:
  • Substrate replacement depends on the substrate type used for your boa. Paper products such as paper towel or news-paper are to be replaced immediately upon defecation. In the case of mulch substrates, our suggestion is to replace the mulch every two to three months, depending on the condition of the substrate.
Disinfectant:
  • Choosing an appropriate disinfectant to clean your reptiles water bowls, cage, and accessories is essential. A popular product in the pet trade today is F10 Disinfectant. I’ve used and recommended this product.

Conclusion

Bolivian short-tailed boas are beautiful, hardy, and rewarding animals that are a real please to keep. Their relatively low maintenance and good demeanor make them excellent boas for both new keepers and experienced hobbyists.


References

  1. Boa constrictor (LINNAEUS, 1758) – The Reptile Database (Accessed Online, 2017)
  2. Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) – Appendices I, II and III (Accessed Online, 2017)

Captive-bred Reptile Excellence