The Boa constrictor (Boa constrictor spp) is amongst the most popular of all snakes. This is hardly surprising considering the gracious shape, coloration and relative docile nature of this medium-sized constrictor. Boas are among the longest lived of all species of snakes with life spans of twenty years and more.
Boas have a robust body and a fairly narrow neck supporting a triangular head. A great variation exists in coloration and pattern; usually they are described as gray, brown/pinkish snakes with a series of dark saddles running down their back. These saddles become darker and closer together towards the tail. In some animals, the tail takes a reddish coloration. Small black spots cover the whole body, including the ventral surface. These snakes are fast growing, reaching 4-5 feet within a year and may well reach 8 feet and a weight of 22 pounds within 3-4 years.
Boa constrictors live near bodies of fresh water in semi-desert regions, coastal deserts, grasslands, woodlands, rain and dry forests.
Boa constrictors are not known for being aggressive but some may be more temperamental than others. Never trust a boa. Generally these snakes are indifferent to handling once they have been removed from their vivarium, but care should always be taken on the initial capture and removal. These snakes deserve a large enclosure that permits stretching out to full length and enough room to exercise. Alternatively, boas need regular exercise outside of smaller enclosures. All snakes can excrete Salmonella, and therefore routine personal hygiene and the supervision of all child-snake interactions are important.
Boas are crepuscular and nocturnal, which means they are active at twilight, during the night and just before dawn, and they enjoy bathing and climbing. Most will tolerate others in the same enclosure, but particular care is required at feeding, as two snakes may strike at the same prey and injure themselves, possibly causing fatality. It is better to keep boas individually, and bring them together for breeding purposes.
It is vital that the correct environment is created. In general, the floor area of the vivarium should be double the length of the snake.
As a general guide, it is recommended that a single adult boa is kept in a vivarium measuring 6 feet by 2 feet or bigger for exceptionally large specimens. It should be of fiber glass or melamine construction with all internal edges sealed so that it can be washed and cleaned with ease. There should be at least 2 feet of height to enable screened lights and heaters to be situated on the ceiling out of the way of the snakes. Sufficient height will also enable you to secure strong branches for your boa to climb.
Ventilation is probably the most overlooked facet to keeping boas, and many succumb to respiratory infections if adequate ventilation is not provided and drafts are not eliminated. The best approach is a 2 inch strip of fine mesh running along the entire back wall of the cage, with two 12 inch by 3 inch controllable ventilation panels at one end and another at the opposite end. Never reduce ventilation for prolonged periods of time when trying to maintain a higher humidity; such actions will invariably result in respiratory problems. Finally, the sliding glass doors should be 6 millimeters thick and mounted on a 6 inch base to provide the snake with some security.
All cages, whether they are for newborn neonates or pregnant females, should be properly furnished to meet the needs of the individual snake. The floor substrate should be non-toxic, uncontaminated, cheap and easy to replace. Newspaper or artificial turf are recommended. Many specimens will fail to settle down, feed or breed unless they are provided with the security of hide boxes or shelters. Others will ignore shelters and spend their time exposed.
Cardboard boxes are cheap and disposable but cork bark is more attractive and provides a better surface on which to shed. However, cork bark is more expensive, difficult to clean and may harbor mites. Boas, especially when small, are eager to climb and therefore secure branches should be provided, which will also add to the attractiveness of the set-up. Ensure that all branches are secure so that falling and crushing accidents do not occur.
Boas like most constrictors like to bathe for extended periods and therefore a water container large enough for the snake to completely immerse itself is essential, especially if shedding is to occur normally. An accurate thermometer and humidity meter should be permanently positioned within the vivarium for daily observation.
Maintenance is often a matter of common sense with the enclosure checked every day. All fecal material, shed skins and soiled substrate must be removed as soon as possible. Once each week, the water bowl should be thoroughly cleaned to reduce any contamination, and the enclosure should be thoroughly inspected and cleaned. When cleaning, remove and discard all substrate and disposable items. Disinfect and rinse the cage and all permanent furnishings including any branches, cork shelters and water containers. Add new floor substrate and clean furnishings.
Always operate strict quarantine on all new arrivals as serious viral diseases (such as Inclusion Body Disease) can decimate a prized collection.
Temperature and Humidity
In order to provide some degree of back-up, it is advisable to use more than one heat source and an accurate thermostat. Boa constrictors are largely nocturnal with the majority of captive specimens having originated from the equatorial rain forests of northern South America where the ambient temperature is near constant. Consequently, boas are less able to regulate their body temperature between extremes, and therefore, it is important to provide a more accurately controlled temperature gradient which ranges from a maximum basking area at one end to a minimum cool area at the other.
Ceramic heaters, soil-warming cables and under-floor heater mats can be used to provide day and night heating, while illuminating spot-lights can only be used during the day. All heating devices, especially those with a high surface temperature, must be screened off from the snakes if fatal or disfiguring burns are to be avoided. Ceramic heaters and spot lights can be housed within mesh cages while heater mats and warming cables can be hidden under a false floor.
Proportional, auto-dimming thermostats will reduce high surface temperatures, prolong heater life and create a more natural environment without temperature cycling and temperature zones. In all cases check the performance of thermostats with an accurate thermometer.
In general, adult boas should be maintained at 60 to 90 percent humidity and with a temperature gradient of 78 to 94 degrees Fahrenheit; however, a more detailed approach is necessary.
It is obvious that an accurate thermostat is essential if these temperature regimes are to be accurately controlled and maintained. Moderate humidity can be achieved by placing the large water container close to the main heat source. The provision of a humidity chamber is also worthwhile especially during periods of shedding (ecdysis).
Light, both intensity and quality, is less important to most snakes, and the use of spot lights to provide a daytime basking area can also be relied upon to provide the necessary 12 to 14 hours of light every day.
Feeding is normally not a problem with boas unless the husbandry conditions are incorrect. In captivity they should be fed weaned mice (pinkies) that should never be bigger than the girth of the midbody of the snake to prevent the risk of regurgitation. It’s also recommended to feed the animal prekilled rodents in order to prevent possible bites to the snake.
The growth rate of your boa will depend upon how many times you feed it and maintenance of proper temperature in the cage. As a general rule consider the following:
The table above is only a handy guide. Use your own judgment whether your snake needs a bit more or less. As an attentive owner watch your snake for increased activity associated with hunger and searching for food. Fresh drinking water must be provided in a container large enough for the snake to bathe and changed frequently.
Do not overfeed your boa. This may lead to obesity and can cause an early death.
Differentiation between males and females is best achieved by ‘probing’. A blunt lubricated sexing probe is inserted inside the caudal rim of the cloacal, either side of the midline, and directed backwards. In males the probe will pass into the hemipenal sulcus to a depth of 6 to 12 subcaudal scales. In females the probe enters the cloacal gland to a depth of around 4 subcaudal scales. The technique of probing can cause serious harm if undertaken incorrectly, and therefore should only be carried out by experienced persons using the correct tools.
Boas usually breed in the winter, when the night time temperature should be cooled down to 70 to 72 degrees Fahrenheit as most breeding appears to occur between 70 to 75 F. They are unreliable breeders, pairs have failed to breed even when conditions seem excellent, and the use of compatible pairs or larger groups appears to improve results.
As a general rule it is recommended to keep the male and female separately. As the time comes the male is introduced in the female’s cage. The best results are get with captive-raised animals because imported adults may take several years before breeding in captivity.
The quoted gestation length varies from 127 to 249 days (average 167 days) and is likely due to variations in the timing of ovulation, mating and sperm storage. Ovulation appears to be characterized by a distinct mid-body swelling which often subsides. However, 105-108 days from the first skin shed following the appearance of the midbody swelling appears to be an accurate expected birth date.
Females give birth to live young. Babies are born around May to September, and the litter size can vary from 8 to 60 (average 25). Each neonate measures 12 to 24 inches at birth. For the babies’ first feed they should be offered pink or fuzzy mice.