Boa imperator

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Boa imperator
CITES Appendix II (CITES)[2][note 1]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Boidae
Genus: Boa
B. imperator
Binomial name
Boa imperator
Daudin, 1803
Distribution range for Boa imperator
  • Boa imperator Daudin, 1803
  • Boa eques Eydoux & Souleyet, 1842
  • Boa constrictor var. isthmica Garman, 1884
  • Boa constrictor imperator
    Ihering, 1910
  • Boa constrictor imperator
    Forcart, 1951

Boa imperator (or Boa constrictor imperator (in common usage)) is a large, heavy-bodied, nonvenomous species[4] of snake in the genus Boa that is commonly kept in captivity. Boa imperator is part of the family Boidae and is found in Mexico, Central America and South America west of the Andes Mountains (primarily in Colombia).[5] It is commonly called the Central American boa, northern boa, Colombian boa, common boa and common northern boa.


A specimen from the Cayos Cochinos

Boa imperator is a wide-ranging species, living in both Central America and the northern parts of South America.[6] As a result, the appearance of this snake varies greatly depending on the specific locality. As one of the smaller Boa species,[7] they average between 1.3 m (4.2 ft.) and 2.5 m (8.2 ft.) in length when fully grown, but have been known to reach 3.7 m (12 ft.).[8] They usually weigh around 6 kg (13 lb), although females are significantly larger than males. Lifespan in the wild is around 20–30 years, but 40 can be exceeded in captivity.[7]

Although Boa imperator exhibits almost identical patterns to Boa constrictor, this species often has a darker tail, usually dark brown or very dark red. They are, however, usually just as colorful as their counterparts and, like the larger boas, can be bred into a variety of different colors, given the right conditions to breed.

Notably, the species is one of only two in snakes to have a confirmed XY sex chromosome system.[9]

One population is found on the Cayos Cochinos (or the Hog Islands) off the northern coast of Honduras. These are naturally hypomelanistic, which means that they have reduced melanin, thus they are more lightly colored, although they retain the distinctive darker tail that is characteristic of most members of this species. The color of the tail may vary from salmon-pink to orange.

A specimen from Nicaragua

Another well-known population of Boa imperator is the population from Nicaragua. which typically have a compact saddle pattern on their backs that is often circular in shape.[10]

Mainland specimens from Colombia can be among the larger boas, but this species also includes a number of island dwarf populations, such as those from various Caribbean islands. These populations represent the smallest members of the species.


Boa imperator has 55–79 dorsal scales, 225–253 ventral scales, 47–69 subcaudal scales, 18–22 supralabial scales and 1–2 anal scales. [11]


Boa imperator is commonly confused with other Boa species, such as Boa constrictor. Both have very similar patterns, to include a reddening of the lighter colors towards a deeper or darker red on the tail. This has resulted in a non-scientific term - "red-tailed boa" - used to refer to both species (mostly in the pet trade).


Boa imperator was formerly classified as a subspecies of Boa constrictor until DNA sequencing identified B. c. imperator as a separate genetic lineage with 5-7% divergence from B. constrictor.[12]

The boa population from the Pacific Coast of Mexico, previously considered a subspecies of B. constrictor and subsequently of B. imperator, has been separated as another species, Boa sigma.[13]


Scientific name[14] Taxon author[14] Common name Geographic range
B. i. imperator Daudin, 1803 Central American boa, northern boa or Colombian boa The entire range except for the Pearl Islands
B. i. sabogae (Barbour, 1906) Pearl Islands boa[14] The Pearl Islands off the Pacific Coast of Panama in the Gulf of Panama

Certain Boa imperator populations such as the ones in the Cayos Cochinos (or the Hog Islands) off the northern coast of Honduras; the Corn Islands off the eastern coast of Nicaragua; the Tarahumara Mountains in Mexico; Ecuador; etc. are classified as different "locales" of Boa imperator, but not as subspecies.

Geographic range[edit]

Boa imperator can be found in some regions of Mexico, Central America and northwestern Colombia, as well as several islands along the coasts of these areas. The type locality given is "l'Amerique meridionale, principalement au Mexique" (Central America, principally Mexico).[3]

Boa imperator prefers to live in rainforests due to humidity, temperature, cover from potential predators and ample prey.


Boa imperator generally live on their own, and do not interact with any other snakes unless they want to mate. They are crepuscular, but they may bask during the day when night-time temperatures are too low. As semi-arboreal snakes, young Boa imperator may climb into trees and shrubs to forage; however, they become mostly terrestrial as they become older and heavier.[15] Boa imperators 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.[16] Like all snakes, Boa imperators 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 be otherwise.

Hunting and diet[edit]

Boa imperator, like most Boa species, has a varied diet that consists mainly of mammals, birds and lizards.[17] The size of the prey item increases as it ages.

Boa imperator, like other Boa species, are crepuscular ambush predators. They use constriction as the primary means of incapacitating their prey. [17]


Boa imperator is one of the most common snakes kept in captivity; this is mainly due to their calm dispositions, impressive size potential and variety of color and pattern choices. Captive common boas often tolerate being handled for extended periods.[18] Captive Boa imperator are generally fed pre-killed rodents in an attempt to reduce damage to the specimen from the prey and for the sake of being more humane.[18]

This snake species has been a common species in the global pet trade since the 1980s, with 115,131 individuals being exported between 1989 and 2000. [19] Wild caught specimens will often contain parasites, both internal and external. The most common parasite is Ophionyssus natricis or the "reptile mite".

Boa imperator captive breeders will often breed for a specific color or "morph". There are several color and pattern morphs available in the pet trade, such as albino, hypomelanistic, motley and jungle individuals.[18]


  1. ^ Except B. c. occidentalis which is included in Appendix I


  1. ^ Montgomery, C.E. & da Cunha, O. 2018. Boa imperator. The IUCN Red List of Threatened Species 2018: e.T203879A2771951. Downloaded on 05 February 2019.
  2. ^ "Appendices | CITES". Retrieved 2022-01-14.
  3. ^ a b McDiarmid RW, Campbell JA, Touré T. 1999. Snake Species of the World: A Taxonomic and Geographic Reference, vol. 1. Herpetologists' League. 511 pp. ISBN 1-893777-00-6 (series). ISBN 1-893777-01-4 (volume).
  4. ^ "Boa constrictor imperator". Integrated Taxonomic Information System. Retrieved 7 July 2008.
  5. ^ Boa imperator at the Reptile Database
  6. ^ "Reptile Guru Care Sheet". Archived from the original on 2011-07-15. Retrieved 2011-03-03. There are several forms of Red Tail Boas ranging from Mexico, Central America, and South America. Some of the more popular types of Boas are Hogg Island, Argentine, Colombian, Peruvian and Suriname.
  7. ^ a b Cotswold Wildlife Park and Gardens Archived October 23, 2007, at the Wayback Machine
  8. ^ "Common Boa Constrictor - Boa constrictor imperator". Retrieved 2013-04-18.
  9. ^ Gamble, Tony; Castoe, Todd A.; Nielsen, Stuart V.; Banks, Jaison L.; Card, Daren C.; Schield, Drew R.; Schuett, Gordon W.; Booth, Warren (2017). "The Discovery of XY Sex Chromosomes in a Boa and Python". Current Biology. 27 (14): 2148–2153.e4. doi:10.1016/j.cub.2017.06.010. PMID 28690112.
  10. ^ "". Archived from the original on 2013-02-04. Retrieved 2013-04-18.
  11. ^ Lotte, Jose; Lotte, Ben (1996). "Taxonomy and Description of Boa Constrictor" (PDF). Litteratura Serpentium. 16 (#3): 78–81. Retrieved 2018-10-22.
  12. ^ Krysko, Kenneth (March 2017). "Boa imperator (Central American Boa)". CABI Digital Library. doi:10.1079/cabicompendium.112730. Retrieved 2023-12-26.
  13. ^ Card, Daren C.; Schield, Drew R.; Adams, Richard H.; Corbin, Andrew B.; Perry, Blair W.; Andrew, Audra L.; Pasquesi, Giulia I.M.; Smith, Eric N.; Jezkova, Tereza; Boback, Scott M.; Booth, Warren (September 2016). "Phylogeographic and population genetic analyses reveal multiple species of Boa and independent origins of insular dwarfism" (PDF). Molecular Phylogenetics and Evolution. 102: 104–116. doi:10.1016/j.ympev.2016.05.034. PMC 5894333. PMID 27241629. Retrieved 2022-03-28.
  14. ^ a b c Uetz, P.; Freed, P.; Aguilar, R.; Hošek, J., eds. (2022). "Boa imperator". The Reptile Database. Retrieved 2022-03-28.
  15. ^ Mehrtens JM. 1987. Living Snakes of the World in Color. New York: Sterling Publishers. ISBN 0-8069-6460-X.
  16. ^ Stidworthy J. 1974. Snakes of the World. Grosset & Dunlap Inc. ISBN 0-448-11856-4.
  17. ^ a b Boback, Scott M. (2005). "Natural History and Conservation of Island Boas (Boa constrictor) in Belize". Copeia. 2005 (4): 880–885. doi:10.1643/0045-8511(2005)005[0880:NHACOI]2.0.CO;2. S2CID 198154888.
  18. ^ a b c Reptiles Magazine Boa Care sheet
  19. ^ Global Invasive Species Database (GISD) 2015. Species profile Boa constrictor imperator. Available from: [Accessed 23 October 2018]

External links[edit]