Common name: Argentine Boa Constrictor
Scientific name: Boa constrictor occidentalis
Range: Argentina and Paraguay
Average Adult size: 7 to 13 feet (2.1 to 4.0 meters)
Dependent on subspecies Boa constrictors can be found from northern Mexico through Central America (Belize, Guatemala, Honduras, El Salvador, Nicaragua, Costa Rica and Panama) to South America north of 35S (Colombia, Ecuador, Peru, Venezuela, Trinidad and Tobago, Guyana, Suriname, French Guiana, Brazil, Bolivia, Uruguay and Argentina). Also in the Lesser Antilles (Dominica and St. Lucia), on San Andrs, Providencia and many other islands along the coasts of Mexico and Central and South America. The type locality given is "Indiis" -- a mistake, according to Peters and Orejas-Miranda (1970).
Boa constrictors flourish in a wide variety of environmental conditions, from tropical rainforests to arid semi-desert country. However, it prefers to live in rainforests due to the humidity and temperature, natural cover from predators and vast amount of potential prey. It is commonly found in or along rivers and streams, as it is a very capable swimmer. Boa constrictors will also occupy the burrows of medium-sized mammals, where it can hide from potential predators.
Boa constrictors are solitary animals, and will only associate with conspecifics to mate. They are nocturnal, however they may bask during the day when night-time temperatures are too low. As semi-arboreal snakes, young boa constrictor individuals may climb into trees and shrubs to forage, however they become mostly terrestrial as they become older and heavier. Boa constrictors will strike when threatened, and will bite in defense. This bite can be painful, especially from large snakes, but is rarely dangerous. However, care must be taken to ensure that infection doesn't result from the injury. Specimens from Central America are more irritable, hissing loudly and striking repeatedly when disturbed, while those from South America tame down more readily. Like all snakes, Boa constrictors that are in a shed cycle will be more unpredictable. This is because the substance that lubricates between the old skin and the new will make the eyes appear "milky" or "opaque", and as such the snake cannot see very well. This will cause it to be more defensive than it may be otherwise.
All Boa constrictors fall under CITES and are listed under Appendix II, except B.c.occidentalis which is listed in Appendix I. In some regions Boa constrictor numbers have been severely hit by predation from humans and other animals, and over collection for the exotic and snake skin trades. Appendix I, about 800 species, are species that are threatened with extinction and may be affected by trade. Trade in wild-caught specimens of these species is illegal.
This species does well in captivity, usually becoming quite tame. It is a common sight in both zoos and private reptile collections. Though still exported from their native South America in significant numbers, it is widely bred in captivity. When kept in captivity, they are fed mice, rats, rabbits, chickens and chicks depending on the size and age of the individual. Captive longevity is 20 to 30 years, with rare accounts of over 40 years, making them a long-term commitment as a pet. Proper animal husbandry is the most significant factor in captive lifespan, this includes providing adequate space, correct temperatures and humidity and suitable food items.
A thermal gradient should be provided, with a cool end and a warm end where the heat source should be located. The cool end should be maintained at 78-85F (27-29C), and the warm end at 86-92F (30-33C). Temperatures should not be allowed to rise above 95F (35C) or below 75F (24C). Cages that are too cold can cause many health problems, ranging from non digestion of food to pneumonia. The necessary temperature can be provided by a heat mat, ceramic or specific light bulb or other alternative heating systems. All heat sources should be guarded, to prevent burns to the snake, and used in conjunction with a thermostat to prevent overheating. Humidity should be kept above 70%.
Mulch makes a good substrate due to its ability to retain moisture without molding. A water bowl large enough to provide adequate humidity and that the boa can coil within must be provided. Another basic essential is adequate hides, at least two (one in the cool end and one in the warm end). The hides ensure that the snake feels secure, as stress can result in snakes refusing to eat. Shelves or secure branches are often provided so that boas can climb, but this is not an essential. Fake plants and other natural looking decorations are also commonly provided, but again they are not essential.
The general rule for feeding snakes is that a suitable prey item is the girth of the snake at its widest point, as most snakes (including Boa constrictors) can dislocate their jaw to allow the consuming of items larger than the jaw would normally open. Young snakes can be fed once a week, to promote healthy growth. Adults only need to be fed once every month. Overfeeding (or power feeding) the snake can lead to a host of health problems later and can shorten its lifespan. It is natural for snakes to lose their appetite when going into shed as this is a stressful time for them; as such food should not be offered at this time. Water should be changed daily or every other day.
Great Lakes Zoological Society
Helping Conserve Our Endangered Species