The boa constrictor (scientific name also Boa constrictor), also known as the common boa, is a species of large, non-venomous, heavy-bodied snake that is frequently kept and bred in captivity. The boa constrictor is a member of the family Boidae. The species is native to tropical South America. A staple of private collections and public displays, its color pattern is highly variable yet distinctive. Four subspecies are recognized.
Common names Though all boids are indeed constrictors, only Boa constrictor (and its subspecies) is commonly referred to in English as a boa constrictor—the only case of a species being referred to colloquially using its scientific binomial name.
The species and subspecies of B. constrictor are part of a variable, diverse group of New World boids referred to as "red-tailed" boas, comprising the species Boa constrictor and Boa imperator. Within the exotic pet trade, it is known as a "BCC"—an abbreviation of its name—to distinguish it from other boa species, such as Boa imperator ("BCI", for "boa constrictor imperator").
Other regional names include the chij-chan (Mayan), jiboia (Portuguese), dagwe (Sranan Tongo), and macajuel (Trinidadian).Mendes, J. (1986). Cote ce Cote la: Trinidad & Tobago Dictionary. Arima, Trinidad. p. 92.
Subspecies Several subspecies of Boa constrictor have been described in the past, but many of these are poorly differentiated, and further research may redefine many of them. Some appear to be based more on location rather than on biological differences. Boa imperator,CABI Boa Constrictor "CABI", "10/5/2018" Boa nebulosa, Boa orophias and Boa sigma have all been elevated to full species status.
Scientific name Taxon author Common name Geographic range EtymologyB. c. constrictorLinnaeus, 1758red-tailed boa constrictor or red-tailed boaSouth America except for the ranges of the other three subspeciesB. c. longicaudaPrice & Russo, 1991long-tailed boa constrictor or long-tailed boanorthern PeruB. c. occidentalisPhilippi, 1873Argentine boa constrictor or Argentine boaArgentina and ParaguayB. c. ortoniiCope, 1878Orton's boa constrictor or Orton's boaBeolens, Bo; Watkins, Michael; Grayson, Michael (2011). The Eponym Dictionary of Reptiles. Baltimore: Johns Hopkins University Press. xiii + 296 pp. . (Boa constrictor amarali, p. 7; B. c. ortonii, p. 196).northwestern PeruThe subspecific name ortonii is in honor of American naturalist James Orton.
Several other subspecies have been described at different times, but currently, these are no longer considered to be valid subspecies by many herpetologists and taxonomists. They include: B. c. amarali Stull, 1932 B. c. melanogaster Langhammer, 1983: a nomen dubium
Description Size and weight The boa constrictor is a large snake, although it is only modestly sized in comparison to other large snakes, such as the reticulated python, Burmese python, or the occasionally sympatric green anaconda, and can reach lengths from depending on the locality and the availability of suitable prey.Maurice, B. International Wildlife Encyclopedia Third Edition. Clear sexual dimorphism is seen in the species, with females generally being larger in both length and girth than males. The usual size of mature female boas is between whereas males are between .Mattison, C. (2007). The New Encyclopedia of Snakes. Princeton University Press. . Females commonly exceed , particularly in captivity, where lengths up to or even can be seen.Wagner, D. "Boas". Barron's. The largest documented non-stretched dry skin is deposited at Zoologische Staatssammlung München (ZSM 4961/2012) and measures without head. A report of a boa constrictor growing up to was later found to be a misidentified green anaconda.Murphy JC, Henderson RW (1997). Tales of Giant Snakes: A Historical Natural History of Anacondas and Pythons. Malabar, Florida: Krieger Publishing Co. .
The boa constrictor is a heavy-bodied snake, and large specimens can weigh up to . Females, the larger sex, more commonly weigh . Some specimens of this species can reach or possibly exceed , although this is not usual.Boa Constrictor Fact Sheet – Woodland Park Zoo Seattle WA . Zoo.org. Retrieved on 2012-08-22.
The size and weight of a boa constrictor depends on subspecies, locale, and the availability of suitable prey. B. c. constrictor reaches, and occasionally tops, the averages given above, as it is one of the relatively large subspecies of Boa constrictor.
Other examples of sexual dimorphism in the species include males generally having longer tails to contain the hemipenes and also longer pelvic spurs, which are used to grip and stimulate the female during copulation.O'Shea M (2007). Boas and Pythons of the World. Princeton, New Jersey: Princeton University Press. . Pelvic spurs are the only external sign of the rudimentary hind legs and pelvis and are seen in all boas and pythons.
Coloring The coloring of boa constrictors can vary greatly depending on the locality. However, they are generally a brown, gray, or cream base color, patterned with brown or reddish-brown "saddles" that become more pronounced towards the tail. This coloring gives B. constrictor subspecies the common name of "red-tailed boas." The coloring works as a very effective camouflage in the jungles and forests of its natural range.
Some individuals exhibit pigmentary disorders, such as albinism. Although these individuals are rare in the wild, they are common in captivity, where they are often selectively bred to make a variety of different color "morphs". Boa constrictors have an arrow-shaped head with very distinctive stripes on it: One runs dorsally from the snout to the back of the head; the others run from the snout to the eyes and then from the eyes to the jaw.
Boa constrictors can sense heat via cells in their lips, though they lack the labial pits surrounding these receptors seen in many members of the family Boidae. Boa constrictors also have two lungs, a smaller (non-functional) left and an enlarged (functional) right lung to better fit their elongated shape, unlike many colubrid snakes, which have completely lost the left lung.
Distribution and habitat Depending on the subspecies, Boa constrictor can be found through South America north of 35°S (Colombia, Ecuador, Peru, Venezuela, Trinidad and Tobago, Guyana, Suriname, French Guiana, Brazil, Bolivia, Uruguay, and Argentina), and many other islands along the coasts of South America. Introduced populations exist in Cozumel, extreme southern Florida, and St. Croix in the U.S. Virgin Islands. The type locality given is "Indiis"—a mistake, according to Peters and Orejas-Miranda (1970).McDiarmid RW, Campbell JA, Touré TA (1999). Snake Species of the World: A Taxonomic and Geographic Reference Volume 1. Washington, District of Columbia: Herpetologists' League. (series). (volume).
B. constrictor flourishes in a wide variety of environmental conditions, from tropical rainforests to arid semidesert country.Stidworthy J (1974). Snakes of the World. New York: Grosset & Dunlap Inc. . However, it prefers to live in rainforest 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 also occupy the burrows of medium-sized mammals, where they can hide from potential predators.
Behavior
Boa constrictors generally live on their own and do not interact with any other snakes unless they want to mate. They are nocturnal, but they may bask during the day when night-time temperatures are too low. As semi-arboreal snakes, young boa constrictors may climb into trees and shrubs to forage; however, they become mostly terrestrial as they become older and heavier.Mehrtens JM (1987). Living Snakes of the World in Color. New York: Sterling Publishers. . Boa constrictors strike when they perceive a threat. Their bite can be painful, especially from large snakes, but is rarely dangerous to humans. Specimens from Central America are more irascible, hissing loudly and striking repeatedly when disturbed, while those from South America tame down more readily. Like all snakes, boa constrictors in a shed cycle are more unpredictable, because the substance that lubricates between the old skin and the new makes their eyes appear milky, blue, or opaque so that the snake cannot see very well, causing it to be more defensive than it might otherwise be.
Hunting and diet
Their prey includes a wide variety of small to medium-sized mammals and birds. The bulk of their diet consists of rodents (such as squirrels, mice, rats and agoutis), but frogs, larger lizards (such as ameivas, iguanas and tegus) and mammals as big as monkeys, marsupials (opossums), introduced mongooses, armadillos, wild pigs, young brocket deer and ocelots are also reported to have been consumed.Boa Constrictor | West Indian Boas. westindianboas.org/west-indian-boas/genus-boa/boa-constrictor. Accessed 20 Sept. 2025. Domestic animals such as dogs, cats, rabbits, ducks and chickens are frequently consumed. Young boa constrictors eat small mice, birds, bats, lizards, and amphibians. The size of the prey item increases as they get older and larger. Once a boa constrictor has caught its prey, it will wrap its coils around the animal and constrict it until it dies by asphyxiation. The boa's powerful muscles allow it to exert a great deal of pressure, and the prey is typically killed within a few minutes.
Boa constrictors are ambush predators, so they often lie in wait for an appropriate prey to come along, then they attack a moment before the prey can escape. However, they have also been known to actively hunt, particularly in regions with a low concentration of suitable prey, and this behavior generally occurs at night. The boa first strikes at the prey, grabbing it with its teeth; it then proceeds to constrict the prey until death before consuming it whole. Unconsciousness and death likely result from shutting off vital blood flow to the heart and brain, causing asphyxiation, rather than suffocation as was previously believed; constriction can interfere with blood flow and overwhelm the prey's usual blood pressure and circulation. This would lead to unconsciousness and death very quickly. Their teeth also help force the animal down the throat while muscles then move it toward the stomach. It takes the snake about 4–6 days to fully digest the food, depending on the size of the prey and the local temperature. After this, the snake may not eat for a week to several months, due to its slow metabolism.
Reproduction and development