The Boa genus contains 3 known species: Boa constrictor, Boa imperator, and Boa sigma. Until the last decade, it was thought that it was a monotypic genus containing only B. constrictor. Although many snakes of different genera belonging to the family Boidae are referred to as “boas,” only members of this genus are “true” boas.
There are 8 official subspecies of B. constrictor and many more localities (geographically-unique “families” that vary enough genetically to be acknowledged as different, but not so much that they are categorized as a new subspecies). Note that most boas available in captivity are hybrids of different localities and sometimes different subspecies.
More detailed resources for subspecies identification can be found at Boa-Constrictors.com and this handy comparison chart here.
Boa constrictor constrictor (“True” Red-Tailed Boa)
B. c. constrictor is what most people think of when they hear the name: big, thick, and bright red patterning on the tail — although they tend to be much more docile than most assume. They typically have bat-shaped saddle patches with dark spots in between, although the Suriname locality has more of an hourglass shape to its pattern. Some localities also have a brown or dark brown tail instead of the namesake red, and they experience a color change as they age: from grayish babies to yellow and brown tones developing later.
They have the potential to get up to 12’ (3.7m) long, but this is rare; most B. c. constrictor average between 7-10’ (2.1-3.0m) — especially when allowed to grow slowly (read: naturally) rather than power-fed.
B. c. constrictor is native to South America east of the Andes Mountains, particularly in the Amazon rainforest. Specimens have been documented in Bolivia, Brazil, Colombia, Ecuador, French Guyana, Guyana, Peru, Suriname, Trinidad and Tobago, and Venezuela.
- Belem (Iquitos/Pucallpa boa)
- Brazil (Iquitos/Pucallpa boa)
- Guyana (Apure/Bolivar boa)
- Peru (Iquitos/Pucallpa boa)
- Suriname (Pokigron boa)
- Venezuela (Apure/Bolivar boa)
Note that B. c. melanogaster was recently reclassified as B. c. constrictor.
Boa imperator (Central American Boa/Common Boa)
B. imperator used to be classified as a subspecies of Boa constrictor until DNA sequencing identified imperator as a distinct genetic lineage with 5-7% sequence divergence from constrictor. Widespread acceptance is still pending, but several publications have acknowledged the new name since the original research was published in 2009. (You can refer to this CABI datasheet for details.)
The Central American Boa tends to be the most docile of the Boa genus, and is the most common species available in the pet trade. Some sources argue that it is one of the best beginner snakes a reptile enthusiast can have. I disagree, simply because they are larger than most “easy” snakes, making them slightly more difficult to handle and much more difficult to house, requiring an enclosure that is both tall and wide. However they are reasonably hardy, don’t get sick easily, have a ready feeding response, and possess a slender build between 5-7’ (1.5-2.1m) long on average. Certain localities top out at 3-5’ due to a locale-specific dwarf gene.
This species can be found west of the South American Andes, throughout Central America and in parts of Mexico. It has been documented in the following countries: Belize, Colombia, Costa Rica, El Salvador, Ecuador, Guatemala, Honduras, Mexico, Nicaragua, Panama, Peru, and Venezuela.
- Belize (Crawl Cay, Caulker Cay)
- Colombia (Barranquilla)
- Honduras (Hog Island, Roatan)
- Mexico (Tarahumara Mountains, Sonoran, Tamaulipas, Cancun)
- Nicaragua (Corn Island)
- Paraguayan Peninsula (Costa Rica, Ecuador, El Salvador, Panama, Venezuela)
B. imperator is the subspecies most commonly available in the US, particularly because it is the most popular for use in breeding for ”morphs” — unique variations in color and/or pattern than deviate from the wild type. For this reason, it is difficult to describe a specific color or pattern that describes B. imperator.
Boa constrictor longicauda (Peruvian Long Tail Boa)
B. c. longicauda hails from the Tumbes province of Northern Peru and typically does not exceed 6’ (1.8m). It can be identified by a black and white or black and gold coloration, with distinctive spear-shaped banding behind the eyes and an arrowhead shaped marking between the eyes. This makes it very similar to B. c. ortonii; some consider B. c. longicauda as just a color variant of this subspecies. However it does have some pattern and color morphs available, and the color contrast increases with age.
Contrary to its name, B. c. longicauda does not have the longest tail of all boa constrictor species. Some say that B. c. longicauda is the perfect boa for people who like the idea of a snake with a boa’s personality, but are worried about size, and they are considered one of the calmest Boas.
Wild B. c. longicauda are becoming increasingly rare due to human-related habitat destruction.
Boa constrictor occidentalis (Argentine Boa)
B. c. occidentalis is from the area from Argentina through Paraguay. These are some of the largest Boas, with females averaging around 10’ (3m) long, and males smaller. It is dark brown/black in color, with a distinctive lighter pattern that increases in contrast with age. Captive individuals are bred to maximize this patterning, and some color and pattern morphs are available.
This subspecies is quite rare in the wild, and categorized in CITES Appendix I as threatened with extinction due to agriculture-related deforestation.
Boa constrictor orophias (St. Lucia Boa)
This subspecies is from St. Lucia island in the Lesser Antilles. They can grow over 10’ (3m) long — at least one 12′ individual has been reported by herpers — and possess pale medium-brown coloring with gray flanks and irregularly shaped, dark brown saddle patches. Saddle patches in the tail region are extremely dark on adults, almost black. This species is extremely proficient at climbing and spends a great deal of time in trees in the wild, even as adults.
B. c. orophias is endangered by fear-based slaughter from locals. They don’t breed well in captivity, and as a result St. Lucia boas are one of the most expensive non-morphed species on the market.
Boa constrictor ortonii (Macanche Boa/Orton’s Boa)
B. c. ortonii’s native range is the dry woodlands from the South Tumbes province to the mountainous regions of La Libertad in Peru. Cajamarca marks the eastern boundary. This subspecies tolerates lower than average temperatures, as well as humidity, and may benefit from a winter brumation period in captivity. However, B. c. ortonii is extremely rare in captivity and possibly nonexistent.
Females average 9.2’ (2.8m) long, with males averaging smaller. This subspecies is endangered in the wild.
Boa constrictor nebulosa (Clouded Boa)
B. c. nebulosa is native to the island Dominica in the Lesser Antilles, a mountainous island that boasts over 360 rivers. It is an extremely wet and muddy environment that receives daily rainfall. It also features a variety of microhabitats which can swing widely from 90°F in one area to 75°F just 20′ away.
This boa subspecies is characterized by a gray-brown coloration and a gray spotted belly, with subtle patterning that gives rise to its common name, the Clouded Boa. Its pattern also displays more saddle patches than any other subspecies. Females average up to 10’ (3m) long, although individuals with genetics from the southern region of the island top out at 8′ while those from the northern region can grow to 10′ or longer. Clouded boas are very slender, proficient climbers and spend lots of their time in trees in the wild, even as adults. They also tend to shelter during the day in agouti burrows/dens as well as caves, sharing the space with other boas.
B. c. nebulosa is listed in Appendix 2 of CITES, but is actually very plentiful on the island due to a lack of habitat destruction. They are rare in captivity, however, as they are very difficult to breed. It should be noted that newborn and young clouded boas prefer lizard prey over rodents, and are likely to starve to death if not offered lizards or at least scented rodents.
Boa constrictor sabogae (Pearl Island Boa)
As its common name suggests, this subspecies is native to the Pearl islands, as well as the islands of Cha Mar, Toboga, and Taboguilla off the coast of Panama. The normal type is typically beige-brown in color and darkens with age, but light pink/red (hypomelanistic) individuals have been recorded in the wild. Pearl Island boas can be identified by uniquely incomplete saddle patches which feature bright orange tones. The head also tends to be much lighter in color than the rest of the body, and the middle line on the head is interrupted between the snake’s eyes. Females average just under 6’ (1.8m) long.
Native populations of Pearl Island boas are in great danger due to fear-based slaughter by humans. It is not known for certain whether there are any healthy populations left in the wild, but they breed well in captivity, making them fairly available to anyone interested in keeping this unique species.
Boa constrictor amarali (Bolivian Silver Back/Short Tail Boa)
B. c. amarali is native to southeast Bolivia and southern/southwest Brazil. Brazilian locales tend to average 5.5’ to just over 6’ (1.7-1.8m) long and the Bolivian locales tend to be slightly larger at 6-7’ (1.8-2.1m) long. Their basic pattern features bat-shaped saddle patches (sometimes referred to as “widows peaks”) that tend to be more distinct than those of B. c. constrictor. True to their name, the basic color for this subspecies is a shiny silver and black. They also have the shortest tail of all the subspecies.
B. c. amarali is endangered in the wild by habitat destruction. There is some speculation as to whether B. c. amarali is a local variant of B. c. constrictor; this requires further genetic testing to confirm.
Boa sigma (Sonoran Boa)
Boa sigma is native to the Pacific coast of Mexico, west of the Isthmus of Tehuantepec. It used to be considered an outdated classification, but has since been resurrected as its own species in Phylogeographic and population genetic analyses reveal multiple species of Boa and independent origins of insular dwarfism by Daren C. Card et al.
Photo available here.
- Introduction to Boa Constrictors
- Members of the Boa Genus
- Boa Constrictor Shopping List — Supplies You Will Need
- How to Select and Buy a Pet Boa
- How Big Should Your Boa’s Enclosure Be?
- Lighting & UVB Requirements
- Temperature Requirements
- Humidity Requirements
- What Kind of Substrate Should You Use?
- Tips for Decorating Your Boa’s Enclosure
- What Do Boa Constrictors Eat?
- How to Handle Your Pet Boa Constrictor
- What to Do When Your Boa Gets Sick
- Additional Resources