The Cold Blooded News The Newsletter of the Colorado Herpetological Society Volume 28, Number 11;   November, 2001

Husbandry and Breeding of the Common Boa in Captivity

by Greg Bracken

Identification is problematic, with many common names invented to describe colour and patterns, such as Red-tails. In fact boas are highly polymorphic. There are 8 recognized subspecies, 4 of which occur on the mainland, with geographical variations within each. Even from the same area, differently marked specimens can be found. Unfortunately man's need to label everything complicates the issue more. For example a Surinam boa may be identical to one from just across the border in Guyana, but coming from different countries, they are labeled as different types of animals.

The boas themselves do not recognize man made borders, and genetic drift will occur between populations on different sides of the border. To make matters worse, the subspecies intergrade where they overlap, so to properly identify your boa the country of origin is not enough; you almost need to know exactly where it was collected, or where the ancestral stock was collected.

Breeding is a much less complicated issue, although it still poses many challenges. Regular breeding does occur, but captive breeding is not producing a volume equivalent to the large number sold as pets each year; undoubtedly many are still imported as wild caught stock. Breeding is more difficult in boas from the Amazon basin (often regarded as true red-tails), which tend to be larger animals overall.

Housing:
All of our adult boas are housed in plywood cages finished with linoleum floors and marine enamel on all the other interior surfaces. Cage dimensions are 18" high x 24" deep x 72" long. All cages are vented, have sliding glass fronts, and are heated by electrical heat tape covered with aluminum along the back edge to create a gradient. A dimmer switch is used to adjust the temperature. Wood shavings are used as a substrate and water is provided fresh daily in a large dish.

The entire reptile room is heated to a base temp of 80°F, and is illuminated via fluorescent and incandescent lighting.

Neonates are housed in Rubbermaid containers in shelving lined with heat tape.

Animals:
We currently maintain 34 adults in our breeding group. The females range from 7-9 feet and the males from 6-7½ feet. The animals range from 5-9 years in age.

Cycling:
Our form of cycling is based on central Alberta's weather conditions and our own experience. The following method for cycling boas is not the only way to induce breeding, just our way. Before cycling, all animals are checked for health. They need a good body weight, should be free of respiratory problems, and have a faecal checked for parasites.

Females are heavily fed for several months prior to cycling, while the males are kept lean (not skinny), so they are more active.

The night time air temperature is gradually reduced in late September from 80°F to 72°F over a period of 3 weeks. During the day a basking spot is provided at 90-95°F. The night time low is then maintained for 2 weeks. During this time it is important to monitor animals for signs of respiratory stress. If any problems are noticed the animal(s) in question are returned to a normal temperature (better alive than bred and dead). Following the two weeks of low night temperature, the animals are then warmed back up to a night time low of 80°F over another 3 week period. Temperatures are always changed gradually so as not to shock the animals.

The animals are not offered food for 2 weeks prior to the initial cool down and are not fed until after they have been warmed back up again.

Lighting is not used to cycle the animals, they are maintained year round at a 12/12 day/night split. Females are housed individually and the males are introduced during the cooling.

Multiple males are used when possible. We have noticed that the weather seems to play a role. When a winter storm hits, the animals go into a breeding frenzy. This is probably related to the barometric pressure changes associated with a storm front, as the animals are maintained indoors and are untouched by the sub-zero temperatures outdoors, which obviously would kill them.

When the males are introduced to the females' cages, daily misting commences in order to raise humidity. This seems also to act as a stimulant and the misting is continued for the duration of the breeding.

An abdominal lump (release of ova) is noticed a little over halfway down the female's body about 30-60 days after copulation. This only lasts a few days at most, and is not always observed.

Gestation can last anywhere from 4-10 months, and it is not uncommon for the females to keep feeding during this time. It is advisable to feed them smaller food items as the amount of space in the body cavity becomes reduced with the enlarging embryos. We have one female who fed the day before parturition (giving birth).

In the later stages of gestation, the last half of the females body becomes enlarged, and she may bask more frequently and lay on her side or back while doing so. It is best not to handle or disturb the female at this time to avoid damaging the young inside her.

The pre-birth shed occurs with many species. In boas it is not an accurate indicator and can vary from 20-38 days in our experience.

Young:
Litter size can range from around 10 to over 80. with the larger females producing more offspring than smaller ones. Other factors can play a role as well, such as the amount of body fat a female carries before ovulation, and genetics.

Young can range in size from 12-24" and be between 2-4 oz. The [size of the] female may have some relation to the size of the young.

The newborn boas are removed from the mother's cage as soon as possible, and any young still in the amniotic sac are removed from it. They are placed in Rubbermaid containers with moist paper towels and are kept moist until their first shed at 10-14 days old. Feeding of the young boas does not commence until after the first shed, at which time they have usually used up all the yolk left in their stomachs. Fuzzy mice are offered initially and usually adult mice will be taken within 6 weeks of first feeding.

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