Boa constrictor

{{Short description|Species of snake}} {{About|the species of snake}} {{Speciesbox | italic_title = no | name = Boa constrictor | image = Red-tailed boa (Boa constrictor constrictor) Rio Napo.jpg | image_caption = Red-tailed boa (''B. c. constrictor'')<br />in Ecuador | status = LC | status_system = IUCN3.1 | status_ref = <ref name=IUCN>{{cite iucn |author=Arzamendia, V. |author-link=species:Vanesa Arzamendia |author2=Cisneros-Heredia, D.F. |author2-link=species:Diego Francisco Cisneros-Heredia |author3=Fitzgerald, L. |author3-link=species:Lee A. Fitzgerald |author4=Flores-Villela, O. |author4-link=species:Oscar Flores-Villela |author5=Gagliardi, G. |author5-link=species:Giussepe Gagliardi-Urrutia |author6=Giraudo, A. |author6-link=species:Alejandro Raúl Giraudo |author7=Ines Hladki, A. |author7-link=species:Adriana Inés Hladki |author8=Köhler, G. |author8-link=Gunther Köhler |author9=Lee, J. |author9-link=species:Julian C. Lee |author10=Nogueira, C. de C. |author10-link=species:Cristiano de Campos Nogueira |author11=Ramírez Pinilla, M. |author11-link=species:Martha Patricia Ramírez-Pinilla |author12=Renjifo, J. |author12-link=species:Juan Manuel Renjifo |author13=Scrocchi, G. |author13-link=species:Gustavo Scrocchi |author14=Urbina, N. |author14-link=species:Nicolas Urbina |author15=Williams, J. |author15-link=species:Jorge Daniel Williams |author16=Wilson, L.D. |author16-link=species:Larry David Wilson |author17=Murphy, J. |author17-link=species:James B. Murphy |year=2021 |title=''Boa constrictor '' |volume=2021 |article-number=e.T197462A2486405 |doi=10.2305/IUCN.UK.2021-2.RLTS.T197462A2486405.en |access-date=27 March 2022}}</ref> | status2 = CITES_A2 | status2_system = CITES | status2_ref = <ref>{{Cite web|title=Appendices {{!}} CITES|url=https://cites.org/eng/app/appendices.php|access-date=2022-01-14|website=cites.org|archive-date=2010-02-04|archive-url=https://web.archive.org/web/20100204020215/http://www.cites.org/eng/app/appendices.shtml|url-status=live}}</ref>{{NoteTag|Except ''B. c. occidentalis'', which is included in Appendix I}} | genus = Boa | species = constrictor | authority = Linnaeus, 1758 | synonyms = *[''Boa''] ''Constrictor'' <br />{{small|Linnaeus, 1758}} *''Constrictor formosissimus'' <br />{{small|Laurenti, 1768}} *''Constrictor rex serpentum'' <br />{{small|Laurenti, 1768}} *''Constrictor auspex'' <br />{{small|Laurenti, 1768}} *''Constrictor diviniloquus'' <br />{{small|Laurenti, 1768}} *[''Boa''] ''constrictrix'' <br />{{small|— Schneider, 1801}} *''Boa diviniloqua'' <br />{{small|— A.M.C. Duméril & Bibron, 1844}} *''Boa constrictor'' <br />{{small|— Boulenger, 1893}} *''Boa diviniloqua'' <br />{{small|— Boulenger, 1893}} *''Constrictor constrictor'' <br />{{small|— Griffin, 1916}} *''Constrictor constrictor constrictor'' <br />{{small|— Stull, 1935}} *''Boa constrictor constrictor'' <br />{{small|— Forcart, 1951}} | synonyms_ref = <ref name="McD99"/> | range_map = Boa_Constrictor_Range.svg | range_map_caption = Distribution<ref name=Card2016>{{Cite journal |last1=Card |first1=Daren C. |last2=Schield |first2=Drew R. |last3=Adams |first3=Richard H. |last4=Corbin |first4=Andrew B. |last5=Perry |first5=Blair W. |last6=Andrew |first6=Audra L. |last7=Pasquesi |first7=Giulia I.M. |last8=Smith |first8=Eric N. |author8-link=species:Eric Nelson Smith |last9=Jezkova |first9=Tereza |last10=Boback |first10=Scott M. |last11=Booth |first11=Warren |last12=Castoe |first12=Todd A. |author12-link=species:Todd A. Castoe |date=September 2016 |title=Phylogeographic and population genetic analyses reveal multiple species of ''Boa'' and independent origins of insular dwarfism |url=http://www.herp.mx/pubs/2016-Card-et-al-Boa.pdf |journal=Molecular Phylogenetics and Evolution |language=en |volume=102 |pages=104–116 |doi=10.1016/j.ympev.2016.05.034 |pmc=5894333 |pmid=27241629 |bibcode=2016MolPE.102..104C |access-date=2022-03-30 |archive-date=2022-02-03 |archive-url=https://web.archive.org/web/20220203072054/http://www.herp.mx/pubs/2016-Card-et-al-Boa.pdf |url-status=live }}</ref> }}

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.<ref name=":1">{{cite web |url=https://www.thespruce.com/snake-species-1239472 |title=Snake Species Commonly Kept as Pets |first=Adrienne |last=Kruzer |date=May 15, 2018 |website=The Spruce Pets |access-date=May 4, 2017 |archive-date=August 17, 2017 |archive-url=https://web.archive.org/web/20170817165752/https://www.thespruce.com/snake-species-1239472 |url-status=live }}</ref>{{r|rdb}} 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.<ref name="ReptileDB"/>

==Common names== Though all boids are indeed constrictors, only ''Boa constrictor'' (and its subspecies) is commonly referred to, in English, as a '''boa constrictor'''—an example 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 scientific name—to distinguish it from other boa species, such as ''Boa imperator'' (known as "BCI" or "boa constrictor imperator").

Other regional names include the ''chij-chan'' (Mayan),<ref>{{cite journal |last=Helmke |first=Christophe |year=2013 |url=http://www.mesoweb.com/pari/publications/journal/1402/Calques.pdf |title=Mesoamerican Lexical Calques in Ancient Maya Writing and Imagery |journal=The PARI Journal |volume=14 |issue=#2<!-- |pages=1–15 --> |at=p.&nbsp;4 |access-date=2014-02-18 |archive-date=2014-02-22 |archive-url=https://web.archive.org/web/20140222061045/http://www.mesoweb.com/pari/publications/journal/1402/Calques.pdf |url-status=live }}</ref> ''jiboia'' (Portuguese), ''dagwe'' (Sranan Tongo), and ''macajuel'' (Trinidadian).<ref>Mendes, J. (1986). Cote ce Cote la: ''Trinidad & Tobago Dictionary''. Arima, Trinidad. p.&nbsp;92.</ref>

==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.<ref name="home.att"/> ''Boa imperator'',<ref>[https://www.cabi.org/isc/datasheet/112730#27d624be-93e6-4fa3-92e5-d37fbf3c56f6 CABI Boa Constrictor] {{Webarchive|url=https://web.archive.org/web/20181006075641/https://www.cabi.org/isc/datasheet/112730#27d624be-93e6-4fa3-92e5-d37fbf3c56f6 |date=2018-10-06 }} "CABI", "10/5/2018"</ref> ''Boa nebulosa'',<ref name=Card2016/> ''Boa orophias'' and ''Boa sigma''<ref>{{Cite web |editor-last=Uetz |editor-first=P. |editor-link=species:Peter Uetz |editor-last2=Freed |editor-first2=P. |editor2-link=species:Paul Freed |editor-last3=Aguilar |editor-first3=R. |editor3-link=species:Rocío Aguilar |editor-last4=Hošek |editor-first4=J. |editor4-link=species:Jiří Hošek |year=2022 |title=''Boa sigma'' |url=https://reptile-database.reptarium.cz/species?genus=Boa&species=sigma |access-date=2022-03-28 |website=The Reptile Database |archive-date=2022-03-28 |archive-url=https://web.archive.org/web/20220328095046/https://reptile-database.reptarium.cz/species?genus=Boa&species=sigma |url-status=live }}</ref> have all been elevated to full species status.

{| class="wikitable" |- ! Scientific name<ref name="ReptileDB">{{Cite web |editor-last=Uetz |editor-first=P. |editor-last2=Freed |editor-first2=P. |editor-last3=Aguilar |editor-first3=R. |editor-last4=Hošek |editor-first4=J. |year=2022 |title=''Boa constrictor'' |url=https://reptile-database.reptarium.cz/species?genus=Boa&species=constrictor |access-date=2022-03-28 |website=The Reptile Database |archive-date=2021-10-09 |archive-url=https://web.archive.org/web/20211009094210/https://reptile-database.reptarium.cz/species?genus=Boa&species=constrictor |url-status=live }}</ref> ! Taxon author<ref name="ReptileDB"/> ! Common name ! Geographic range ! Etymology |- |''B. c. constrictor'' |Linnaeus, 1758 |red-tailed boa constrictor or red-tailed boa |South America except for the ranges of the other three subspecies<ref name="germany">{{cite web |url=http://www.boa-constrictors.com/com/com.html |title=Boa constrictor Page |publisher=Boa-constrictors.com |access-date=2010-03-15 |archive-date=2010-03-25 |archive-url=https://web.archive.org/web/20100325185335/http://www.boa-constrictors.com/com/com.html |url-status=live }}</ref> | |- |''B. c. longicauda'' |Price & Russo, 1991 |long-tailed boa constrictor or long-tailed boa |northern Peru<ref name="germany"/> | |- |''B. c. occidentalis'' |Philippi, 1873 |Argentine boa constrictor or Argentine boa |Argentina and Paraguay<ref name="germany"/> | |- |''B. c. ortonii'' |Cope, 1878 |Orton's boa constrictor or Orton's boa<ref name=EDR>Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). ''The Eponym Dictionary of Reptiles''. Baltimore: Johns Hopkins University Press. xiii + 296 pp. {{ISBN|978-1-4214-0135-5}}. (''Boa constrictor amarali'', p. 7; ''B. c. ortonii'', p. 196).</ref> |northwestern Peru<ref name="germany"/> |The subspecific name ''ortonii'' is in honor of American naturalist James Orton.<ref name=EDR/> |}

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.<ref name="boasub">{{cite web |url=http://www.boa-subspecies.com/subspecies/melanogaster.htm |title=The Boa Constrictor Subspecies&nbsp;– Melanogaster |publisher=Boa-subspecies.com |access-date=2010-03-15 |archive-date=2012-03-20 |archive-url=https://web.archive.org/web/20120320100857/http://www.boa-subspecies.com/subspecies/melanogaster.htm |url-status=live }}</ref> They include: * ''B. c. amarali'' Stull, 1932<ref name="ReptileDB"/> * ''B. c. melanogaster'' Langhammer, 1983: a ''nomen dubium''<ref name="ReptileDB"/>

==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 {{convert|3|to|13|ft|m|abbr=on}} depending on the locality and the availability of suitable prey.<ref name="maurice">Maurice, B. ''International Wildlife Encyclopedia'' Third Edition. {{ISBN|0-7614-7266-5}}{{page needed|date=April 2018}}</ref> 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 {{convert|7|and|10|ft|m|abbr=on}} whereas males are between {{convert|6|and|8|ft|m|abbr=on}}.<ref name="mat2007">Mattison, C. (2007). ''The New Encyclopedia of Snakes''. Princeton University Press. {{ISBN|0-691-13295-X}}.{{page needed|date=April 2018}}</ref> Females commonly exceed {{convert|10|ft|m|abbr=on}}, particularly in captivity, where lengths up to {{convert|12|ft|m|abbr=on}} or even {{convert|14|ft|m|abbr=on}} can be seen.<ref name="wagner">Wagner, D. "Boas". Barron's. {{ISBN|0-8120-9626-6}}{{page needed|date=April 2018}}</ref> The largest documented non-stretched dry skin is deposited at ''Zoologische Staatssammlung München'' (ZSM 4961/2012) and measures {{convert|14.6|ft|m|abbr=on}} without head.<ref>{{Cite journal|last1=Glaw|first1=F.|author1-link=Frank Glaw|last2=Franzen|first2=M.|author2-link=species:Michael Franzen|year=2016|title=On the maximum length of ''Boa constrictor'' (Serpentes, Boidae)|url=http://pfeil-verlag.de/wp-content/uploads/2017/05/spix39_2_15.pdf|journal=Spixiana|volume=39|issue=#2|page=264|access-date=2018-02-19|archive-date=2018-02-20|archive-url=https://web.archive.org/web/20180220033114/http://pfeil-verlag.de/wp-content/uploads/2017/05/spix39_2_15.pdf|url-status=live}}</ref> A report of a boa constrictor growing up to {{convert|18.5|ft|m|abbr=on}} was later found to be a misidentified green anaconda.<ref name="Mur97">Murphy JC, Henderson RW (1997). ''Tales of Giant Snakes: A Historical Natural History of Anacondas and Pythons''. Malabar, Florida: Krieger Publishing Co. {{ISBN|0-89464-995-7}}.{{page needed|date=April 2018}}</ref>

The boa constrictor is a heavy-bodied snake, and large specimens can weigh up to {{convert|27|kg|lb|abbr=on}}. Females, the larger sex, more commonly weigh {{convert|10|to|15|kg|lb|abbr=on}}.<ref name="bytes">{{cite web |url=http://www.seaworld.org/Animal-info/animal-bytes/animalia/eumetazoa/coelomates/deuterostomes/chordata/craniata/reptilia/squamata/boa-constrictor.htm |title=ANIMAL BYTES&nbsp;– Boa Constrictor |publisher=Seaworld.org |access-date=2010-03-15 |archive-url=https://web.archive.org/web/20100502025207/http://www.seaworld.org/animal-info/animal-bytes/animalia/eumetazoa/coelomates/deuterostomes/chordata/craniata/reptilia/squamata/boa-constrictor.htm |archive-date=2010-05-02 }}</ref> Some specimens of this species can reach or possibly exceed {{convert|45|kg|lb|abbr=on|sigfig=1}}, although this is not usual.<ref>[http://www.zoo.org/page.aspx?pid=411 Boa Constrictor Fact Sheet – Woodland Park Zoo Seattle WA] {{Webarchive|url=https://web.archive.org/web/20111113084409/http://www.zoo.org/page.aspx?pid=411 |date=2011-11-13 }}. Zoo.org. Retrieved on 2012-08-22.</ref>

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''.<ref name="mat2007"/>

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.<ref name="o2007">O'Shea M (2007). ''Boas and Pythons of the World''. Princeton, New Jersey: Princeton University Press. {{ISBN|1-84537-544-0}}.</ref> 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.<ref name="mat2007"/>

thumb|A juvenile South American boa constrictor 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.<ref name="natzoo">{{cite web |url=http://nationalzoo.si.edu/Animals/ReptilesAmphibians/Facts/FactSheets/Boaconstrictor.cfm |title=Boa Constrictor Fact Sheet |publisher=Nationalzoo.si.edu |access-date=2010-03-15 |archive-url=https://web.archive.org/web/20100209065804/http://nationalzoo.si.edu/Animals/ReptilesAmphibians/Facts/FactSheets/Boaconstrictor.cfm |archive-date=2010-02-09 }}</ref> 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,<ref>{{cite journal |first1=Miguel Angel |last1=Martinez Morales |first2=Alreado D |last2=Cuarón |title=Boa constrictor, an introduced predator threatening the endemic fauna on Cozumel Island, Mexico |journal=Biodiversity and Conservation |volume=8 |number=7 |pages=957–963 |date=July 1999 |doi=10.1023/A:1008815004072 |bibcode=1999BiCon...8..957M |s2cid=19655051 |url=https://www.researchgate.net/publication/225963823 }}</ref> extreme southern Florida,<ref>{{cite web |url=http://myfwc.com/wildlifehabitats/nonnatives/reptiles/common-boa/ |title=Nonnatives – Common Boa |publisher=Florida Fish and Wildlife Conservation Commission |access-date=2015-12-04 |archive-date=2018-10-16 |archive-url=https://web.archive.org/web/20181016055832/http://myfwc.com/wildlifehabitats/nonnatives/reptiles/common-boa }}</ref> and St. Croix in the U.S. Virgin Islands.<ref>{{cite web |last1=Davis |first1=Olasee |title=Exotic snakes are not native, but they are now on St. Croix |date=30 January 2019 |url=http://www.virginislandsdailynews.com/opinion/exotic-snakes-are-not-native-but-they-are-now-on-st-croix/article_35cb5fc7-1614-52b3-8a05-fc6eb8daad31.html |publisher=Virgin Islands Daily News |access-date=2 May 2023}}</ref> The type locality given is "Indiis"—a mistake, according to Peters and Orejas-Miranda (1970).<ref name="McD99">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. {{ISBN|1-893777-00-6}} (series). {{ISBN|1-893777-01-4}} (volume).{{page needed|date=April 2018}}</ref>

''B. constrictor'' flourishes in a wide variety of environmental conditions, from tropical rainforests to arid semidesert country.<ref name="Sti74">Stidworthy J (1974). ''Snakes of the World''. New York: Grosset & Dunlap Inc. {{ISBN|0-448-11856-4}}.</ref> 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.<ref name="mat2007"/>

==Behavior== thumb|upright|A juvenile female boa constrictor in a shed cycle, indicated by the blue opaque eyes 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.<ref name="Meh87">Mehrtens JM (1987). ''Living Snakes of the World in Color.'' New York: Sterling Publishers. {{ISBN|0-8069-6460-X}}.</ref> 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.<ref name="Sti74" /> 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=== {{Main|Constriction}} thumb|A captive boa constrictor strike-feeding on a large (already dead) rat Their prey includes a wide variety of small to medium-sized mammals and birds.<ref name="Meh87"/> 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), armadillos, wild pigs, young brocket deer and ocelots are also reported to have been consumed.<ref name="Sti74"/><ref>{{cite encyclopedia | title=''Boa constrictor'' (Boa Constrictor or Macajuel) | encyclopedia=The Online Guide to the Animals of Trinidad and Tobago | publisher=University of the West Indies | section=Behaviour | access-date=2022-03-22 | first=Samanta Stephanie | last=Ramnarine | date=2011 | url=https://sta.uwi.edu/fst/lifesciences/sites/default/files/lifesciences/images/Boa_constrictor.pdf | archive-date=2022-03-22 | archive-url=https://web.archive.org/web/20220322130231/https://sta.uwi.edu/fst/lifesciences/sites/default/files/lifesciences/images/Boa_constrictor.pdf | url-status=live }}</ref><ref>{{cite web | url=https://herpetologytt.blogspot.com/search?q=Boa+constrictor | title=The Herpetology of Trinidad and Tobago }}</ref><ref name="Red-tailed Boa Boa constrictor">{{cite web | url=https://www.reptilesofecuador.com/boa_constrictor.html | title=Red-tailed Boa (Boa constrictor) }}</ref><ref name=Murphy-1998>{{cite journal |last1=Murphy |first1=John |year=1998 |title=Amphibians and reptiles of Trinidad and Tobago |journal=Copeia |issue=2 |url=https://www.researchgate.net/publication/44431890 }}</ref><ref>Boa Constrictor | West Indian Boas. westindianboas.org/west-indian-boas/genus-boa/boa-constrictor. Accessed 20 Sept. 2025.</ref> Domestic animals such as dogs, cats, rabbits, ducks and chickens are frequently consumed.<ref name="Red-tailed Boa Boa constrictor"/><ref name=Murphy-1998/> 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.<ref name=":1" /> 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.<ref name="bbc_2015">{{cite news |url=https://www.bbc.co.uk/news/science-environment-33625080 |title=Boa constrictors' lethal secret revealed |first=Victoria |last=Gill |work=BBC News |date=July 23, 2015 |access-date=June 22, 2018 |archive-date=August 22, 2018 |archive-url=https://web.archive.org/web/20180822010649/https://www.bbc.co.uk/news/science-environment-33625080 |url-status=live }}</ref> This would lead to unconsciousness and death very quickly.<ref name="bbc_2015" /> 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.<ref>{{cite journal |first1=G. Gene |last1=Montgomery |first2=A. Stanley |last2=Rand |author2-link=species:Austin Stanley Rand |title=Movements, Body Temperature and Hunting Strategy of a Boa constrictor |journal=Copeia |volume=1978 |issue=#3 |year=1978 |pages=532–533 |doi=10.2307/1443622 |jstor=1443622 }}</ref>

===Reproduction and development=== thumb|280px|right|The effects of central fusion and terminal fusion on heterozygosity Boa constrictors are ovoviviparous, giving birth to live young.<ref>{{cite journal |title=Stable isotope tracer reveals that viviparous snakes transport amino acids to offspring during gestation |first1=J.U. |last1=Van Dyke |first2=S.J. |last2=Beaupre |journal=Journal of Experimental Biology |year=2012 |volume=215 |issue=#5 |pages=760–765 |doi=10.1242/jeb.058644|pmid = 22323198|doi-access=free |bibcode=2012JExpB.215..760V }}</ref> They generally breed in the dry season—between April and August—and are polygynous; thus, males may mate with multiple females.<ref name="animaldiv">{{cite web |url=http://animaldiversity.ummz.umich.edu/site/accounts/information/Boa_constrictor.html |title=ADW: Boa constrictor: Information |publisher=Animaldiversity.ummz.umich.edu |access-date=2010-03-15 |archive-date=2011-06-29 |archive-url=https://web.archive.org/web/20110629042805/http://animaldiversity.ummz.umich.edu/site/accounts/information/Boa_constrictor.html |url-status=live }}</ref> Half of all females breed in a given year, and a larger percentage of males actively attempt to locate a mate.<ref name="animaldiv"/> Due to their polygynous nature, many of these males will be unsuccessful. As such, female boas in inadequate physical condition are unlikely to attempt to mate, or to produce viable young if they do mate.<ref name="animaldiv"/> Reproduction in boas is almost exclusively sexual. In 2010, a boa constrictor was shown to have reproduced asexually via parthenogenesis.<ref>{{cite web |url=http://www.livescience.com/animals/first-virgin-birth-boa-constrictors-101103.html |title=Who's Your Daddy? Boa Constrictor Has Virgin Birth |publisher=LiveScience |date=2010-11-03 |access-date=2011-08-01 |archive-date=2020-04-10 |archive-url=https://web.archive.org/web/20200410110417/https://www.livescience.com/10225-daddy-boa-constrictor-virgin-birth.html |url-status=live }}</ref> The Colombian rainbow boa (''Epicrates maurus'') was found to reproduce by facultative parthenogenesis resulting in production of WW female progeny.<ref name="pmid21868391">{{cite journal |author6-link=Coby Schal |vauthors=Booth W, Million L, Reynolds RG, Burghardt GM, Vargo EL, Schal C, Tzika AC, Schuett GW |title=Consecutive virgin births in the new world boid snake, the Colombian rainbow Boa, ''Epicrates maurus'' |journal=Journal of Heredity |volume=102 |issue=#6 |pages=759–63 |year=2011 |pmid=21868391 |doi=10.1093/jhered/esr080 |doi-access=free |url=https://access.archive-ouverte.unige.ch/access/metadata/1cd1f7f5-6547-4656-ab34-7759241999e2/download }}</ref> The WW females were likely produced by terminal automixis (see Figure), a type of parthenogenesis in which two terminal haploid products of meiosis fuse to form a zygote, which then develops into a daughter progeny. This is only the third genetically confirmed case of consecutive virgin births of viable offspring from a single female within any vertebrate lineage. In 2017, boa constrictors, along with ''Boa imperators'' and Burmese pythons, were found to contain a new set of sex determining chromosomes.<ref name=":0">{{Cite journal|date=2017-07-24|title=The Discovery of XY Sex Chromosomes in a Boa and Python|journal=Current Biology|language=en|volume=27|issue=#14|pages=2148–2153.e4|doi=10.1016/j.cub.2017.06.010|pmid=28690112|issn=0960-9822|last1=Gamble|first1=Tony|author1-link=species:Tony Gamble|last2=Castoe|first2=Todd A.|last3=Nielsen|first3=Stuart V.|author3-link=species:Stuart V. Nielsen|last4=Banks|first4=Jaison L.|last5=Card|first5=Daren C.|last6=Schield|first6=Drew R.|last7=Schuett|first7=Gordon W.|last8=Booth|first8=Warren|url=https://epublications.marquette.edu/cgi/viewcontent.cgi?article=1608&context=bio_fac|doi-access=free|bibcode=2017CBio...27E2148G |access-date=2019-08-17|archive-date=2019-04-28|archive-url=https://web.archive.org/web/20190428022700/https://epublications.marquette.edu/cgi/viewcontent.cgi?article=1608&context=bio_fac|url-status=live}}</ref> Males were discovered to contain a pair of XY sex determining chromosomes, while females have a XX pair.<ref name=":0" /> This is the first time snakes were thought to contain male heterogamety; since then it has been found in ball pythons (''Python regius'') as well.<ref>{{Cite journal|last1=Augstenová|first1=Barbora|last2=Johnson Pokorná|first2=Martina|last3=Altmanová|first3=Marie|last4=Frynta|first4=Daniel|author4-link=species:Daniel Frynta|last5=Rovatsos|first5=Michail|author5-link=species:Michail Rovatsos|last6=Kratochvíl|first6=Lukáš|author6-link=species:Lukáš Kratochvíl|date=2018-07-04|title=ZW, XY, and yet ZW: Sex chromosome evolution in snakes even more complicated|journal=Evolution; International Journal of Organic Evolution|volume=72|issue=#8|pages=1701–1707|doi=10.1111/evo.13543|issn=1558-5646|pmid=29972583|bibcode=2018Evolu..72.1701A |s2cid=49679832}}</ref>

During the breeding season, the female boa constrictor emits pheromones from her cloaca to attract males, which may then wrestle to select one to breed with her.<ref name="natzoo"/> During breeding, the male curls his tail around the female's and the hemipenes (or male reproductive organs) are inserted. Copulation can last from a few minutes to several hours and may occur several times over a period of a few weeks.<ref name="sss">{{cite web |url=http://www.ssscales.com/boa_care.html |title=Boa Constrictor Care |publisher=Ssscales |access-date=2010-03-15 |url-status=usurped |archive-url=https://web.archive.org/web/20100219101658/http://www.ssscales.com/boa_care.html |archive-date=2010-02-19 }}</ref> After this period, ovulation may not occur immediately, but the female can hold the sperm inside her for up to one year.<ref name="sss"/> When the female ovulates, a midbody swell can be noticed that appears similar to the snake having eaten a large meal.<ref name="sss"/> The female then sheds two to three weeks after ovulation, in what is known as a post-ovulation shed which lasts another 2–3 weeks, which is longer than a normal shed.<ref name="sss"/> The gestation period, which is counted from the postovulation shed, is around 100–120 days.<ref name="sss"/> The female then gives birth to young that average {{convert|15|–|20|inch|cm|abbr=on}} in length.<ref name="Meh87"/> The litter size varies between females but can be between 10 and 65 young, with an average of 25, although some of the young may be stillborn or unfertilized eggs known as "slugs". The young are independent at birth and grow rapidly for the first few years, shedding regularly (once every one to two months). At 3–4 years, boa constrictors become sexually mature and reach the adult size of {{convert|6|–|10|ft|m}}, although they continue to grow at a slow rate for the rest of their lives.<ref name="home.att">Smith, Charles R. (1999). [https://web.archive.org/web/20050224082535/http://home.att.net/~crinaustin/BoaInfo.pdf Boa constrictor (''Boa constrictor'')]. Siar Anthranir Reptiles</ref> At this point, they shed less frequently, about every 2–4 months.<ref name="sta1986">Stafford, P. (1986). ''Pythons and Boas''. Neptune, New Jersey: T.F.H. Publications. {{ISBN|0-86622-084-4}}.{{page needed|date=April 2018}}</ref>

==Captivity== Though still exported from South America in significant numbers, they are widely bred in captivity.{{Citation needed|date=October 2024}} Captive life expectancy is 20 to 30 years, with rare accounts of over 40 years.<ref>[http://www.ci.manhattan.ks.us/DocumentView.aspx?DID=1299 Reports]{{dead link|date=November 2016 |bot=InternetArchiveBot |fix-attempted=yes }} such as an individual living to 40 years in the Philadelphia Zoo.</ref> The greatest reliable age recorded for a boa constrictor in captivity is 40 years, 3 months, and 14 days. This boa constrictor was named Popeye and died in the Philadelphia Zoo, Pennsylvania, on April 15, 1977.<ref>{{Cite book|title=Guinness World Records 2011|publisher=Guinness World Records|year=2010|isbn=978-1-904994-57-2|page=[https://archive.org/details/guinnessworldrec00/page/63 63]|url=https://archive.org/details/guinnessworldrec00/page/63}}</ref> <!-- how-to, not encyclopedic, poorly written A young boa constrictor should be kept in a relatively small enclosure, such as a secure plastic box or terrarium. As the snake grows, so too should the size of the enclosure. Adults are often housed in {{nowrap|180 cm × 90 cm × 60 cm}} vivariums; however, large females should be placed in larger enclosures. The enclosure's minimum length should be two-thirds of the snake's length.<ref name="herpcentre">{{cite web | title = Common Boa Constrictor (''Boa constrictor imperator'') Caresheet | publisher = Herp Center Network | last = Hitch | first = Rachel | last2 = Brooks | first2 = Richard | url = http://www.herpcenter.com/boa-constrictor-caresheet.html | format = website | access-date = 9 February 2011 | archive-url = https://web.archive.org/web/20110727100213/http://www.herpcenter.com/boa-constrictor-caresheet.html | archive-date = 27 July 2011 | df = dmy-all }}</ref> Snakes in general are kept in separate enclosures, but people have successfully kept females together. It is recommended that male boas should not be kept together, as this can cause stress on the boas and may result in a fight. Glass aquarium-style enclosures are seldom advised by snake keepers, as they do not efficiently maintain temperature and humidity.<ref name="repticzone">{{cite web |url=http://www.repticzone.com/caresheets/823.html |title=(BCI) Boa Constrictor Imperator Care Sheet Information. boa constrictors /u(BCI) Boa Constrictor Imperator Help and Care (BCI) Boa Constrictor Imperator, boa constrictors, care sheets, information on (BCI) Boa Constrictor Imperator Snakes info, (BCI) Boa Constrictor Imperator help |publisher=Repticzone.com |date=2006-04-29 |access-date=2010-03-15 |archive-url=https://web.archive.org/web/20130921125308/http://repticzone.com/caresheets/823.html |archive-date=2013-09-21 }}</ref> A thermal gradient is needed for keeping boa constrictors; the enclosures should have a cool end and a warm end, as well as an easily locatable heat source. The cool end should be maintained at {{convert|75|–|85|F|C}},<ref name="boacare1">[http://www.boa-constrictors.co.uk/care care sheet] {{Webarchive|url=https://web.archive.org/web/20140528122122/http://www.boa-constrictors.co.uk/care |date=2014-05-28 }}. boa-constrictors.co.uk. Retrieved on 2012-08-22.</ref> and the warm end at {{convert|86|–|92|F|C}}.<ref name="herpcentre"/><ref name="repticzone"/><ref name="boacare1"/> Temperatures should not be allowed to rise above {{convert|95|°F|°C|abbr=on}} or drop below {{convert|75|°F|°C|abbr=on}}. Cages that are too cold can cause many health problems, ranging from non-digestion of food to pneumonia.<ref name="home.att"/> The necessary temperature can be provided by a heat mat, a 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 at 50%, and raised to 70% when the boa is in shed.<ref name="boacare1"/> However, high humidity should not be maintained for longer than a week, as this raises the risk of infections such as scale rot.<ref name="herpcentre"/> Humidity levels can be maintained with a water bowl, and raised by adding more water bowls, moving the current water bowl closer to the heat source or misting the enclosure with a water sprayer. Boa constrictors do not need any special lighting but should have approximately 12 hours of light and 12 hours of darkness every day to simulate a natural environment. Either a bulb or natural light can be used to provide such conditions.<ref name="herpcentre"/><ref name="swelluk">{{cite web|author=Fluid Creativity, January 2006, www.fluidcreativity.co.uk |url=http://www.reptiles.swelluk.com/reptile-care/boa-constrictor.html |title=Boa Constrictor |publisher=Reptiles.swelluk.com |access-date=2010-03-15}}</ref>

Inside the enclosure, a substrate, generally of newspaper or aspen shavings, must be provided.<ref name="boacare1"/> Untreated cedar or pine shavings are to be avoided, as they contain oils that are toxic to snakes.<ref>{{cite web|url=http://exoticpets.about.com/cs/guineapigs/a/woodshavings.htm |title=Cedar and Pine Wood Shavings – Problems and Toxicity |publisher=Exoticpets.about.com |date=2010-06-14 |access-date=2011-08-01}}</ref> A water bowl, large enough to provide adequate humidity and that the snake 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).<ref name="boacare1"/> Hides can be anything from empty plastic or wooden boxes to specially made hides from a reptile equipment retailer. 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 essential. Fake plants and other natural-looking decorations are also commonly provided, but again they are not essential.<ref name="boacare1"/> thumb|A boa constrictor in a vivarium. Note the large water bowl.

A young boa's diet in captivity can be small to medium-sized mice and then on to increasing sizes of rats. Most boas will never need a prey item larger than a large rat; however, some big females (8&nbsp;ft+) may require rabbits, guinea pigs and chickens. A suitable prey item for feeding to snakes should be no larger than the girth of the snake at its widest point,<ref name="boacare1"/> as with most snakes (including ''Boa constrictor'') the left and right sides of the lower jaw are joined only by a flexible ligament at the anterior tips, allowing them to separate widely, while the posterior ends of the lower jawbones articulate with a quadrate bone, allowing further mobility, to allow the consumption of large prey. 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.<ref name="swelluk"/> It is natural for snakes to lose their appetite when going into shed, as this is a stressful time for them, so food should not be offered at this time.<ref name="swelluk"/> Water should be changed daily or every other day.

Boas should be handled regularly to maintain their docility. Large boas are very powerful and should be handled by two people.<ref>{{cite web|url=http://exoticpets.about.com/cs/snakes/a/boaconstrictors.htm |title=Boa Constrictors As Pets&nbsp;– Red-Tailed Boas |publisher=Exoticpets.about.com |date=2009-12-14 |access-date=2010-03-15}}</ref> Snakes should never be handled within 48 hours of feeding, due to a risk of regurgitation, or when in a shed cycle.<ref name="boacare1"/>-->

Up to 41.5% of captive boas test positive for eosinophilic inclusion bodies.<ref>{{cite journal |doi=10.1016/j.tvjl.2016.10.006 |pmid=27938703 |title=Detection and prevalence of boid inclusion body disease in collections of boas and pythons using immunological assays |journal=The Veterinary Journal |volume=218 |pages=13–18 |year=2016 |last1=Chang |first1=L |last2=Fu |first2=D |last3=Stenglein |first3=M.D |last4=Hernandez |first4=J.A |last5=Derisi |first5=J.L |last6=Jacobson |first6=E.R }}</ref>

==Economic significance== Boa constrictors are very popular within the exotic pet trade and have been both captured in the wild and bred in captivity. Today, most captive boa constrictors are captive-bred, but between 1977 and 1983, 113,000 live boa constrictors were imported into the United States.<ref name="home.att"/> These huge numbers of wild-caught snakes have put considerable pressure on some wild populations. Boa constrictors have also been hunted for their meat and skins, and are a common sight at markets within their geographic range. After the reticulated python, boa constrictors are the snake most commonly killed for snakeskin products, such as shoes, bags, and other items of clothing.<ref name="home.att"/> In some areas, they have an important role in regulating the opossum populations, preventing the potential transmission of leishmaniasis to humans.<ref name="plo2004">Pough, F. Harvey (2004). ''Herpetology'' (third edition). {{ISBN|0-13-100849-8}}.{{page needed|date=April 2018}}</ref> In other areas, they are often let loose within the communities to control the rodent populations.

==Conservation== All boa constrictors fall under CITES and are listed under CITES Appendix II, except ''B. c. occidentalis'', which is listed in CITES Appendix I.<ref name=CITES>{{cite web |url=http://www.cites.org/eng/app/appendices.shtml |title=Appendices I, II and III |publisher=Cites.org |date=2009-05-22 |access-date=2010-03-15 |archive-date=2007-05-19 |archive-url=https://web.archive.org/web/20070519090502/http://www.cites.org/eng/app/appendices.shtml |url-status=live }}</ref>

In some regions, boa constrictor numbers have been severely hit by predation from humans and other animals and over-collection for the exotic pet and snakeskin trades. Most populations, though, are not under threat of immediate extinction; thus, they are within Appendix II rather than Appendix I.<ref name=CITES/>

Boa constrictors may be an invasive species in Florida and Aruba.<ref>{{Cite web |url=https://www.fort.usgs.gov/FLConstrictors/ |title=Giant Constrictor Snakes in Florida: A Sizeable Research Challenge |access-date=2014-01-25 |archive-date=2014-02-02 |archive-url=https://web.archive.org/web/20140202142349/http://www.fort.usgs.gov/FLConstrictors/ |url-status=live }}{{full citation needed|date=April 2018}}</ref>

==See also== * ''Daletvirus boae''

==Notes== {{NoteFoot}}

==References== {{Reflist|refs= <ref name=rdb>{{NRDB species|genus=Boa|species=constrictor|date=7 November|year=2020}}</ref> }}

==Further reading== *Boulenger GA (1893). ''Catalogue of the Snakes in the British Museum (Natural History). Volume I., Containing the Families ... Boidæ ....'' London: Trustees of the British Museum (Natural History). (Taylor and Francis, printers). xiii + 448 pp. + Plates I–XXVIII. (''Boa constrictor'', pp.&nbsp;117; ''Boa diviniloqua'', p.&nbsp;118). *Linnaeus C (1758). ''Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio Decima, Reformata''. Stockholm: L. Salvius. 824 pp. (''Boa constrictor'', new species, p.&nbsp;215). (in Latin).

{{Taxonbar|from=Q215388}} {{Authority control}}

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