Added February 2002. Last updated 17 September 2009: updated Hog Island Boa, Argentine Boa, Amaral's Boa, Bibliography and Navigation..

A quick guide to

BOA CONSTRICTORS

Introduction

The boa constrictor has long been one of the favourite large snakes of reptile keepers, and for good reason. Unlike some pythons, it has a fairly docile temperament, does not grow to truly enormous sizes and has as far as I know never been implicated in the death of a human being. Most are attractively patterned. They do not make difficult demands on their keepers, they breed fairly readily in captivity and are long-lived, at least twenty years being the norm.

Although there are many different boa constrictors (eg Common, Hog Island, etc), it is important to recognise that these are just subspecies or even mere "phases", and that all boa constrictors belong to the same species, Boa constrictor. This means that different "types" or subspecies can breed readily with one another, just as an alsation dog can with a poodle. For this reason some discrimination is needed: if you plan on breeding boa constrictors or keeping two together, it is recommended that you use the same subspecies or phase. This of course begs the question of whether progeny of a union between different subspecies or phases are "morphs" or "mutts", but my personal view is that usually it is better to conform to nature's work. DeVosjoli et al (see Bibliography) go into phases and morphs in more detail.

The following guide is not intended to supplant the very good books written on the subject of boa husbandry, which again I recommend that you purchase before obtaining a boa. It is simply a potted natural history with some details of the differences between the different subspecies and phases. Nevertheless, there are some general rules for keeping these snakes:

Although snakes in general do not need the large enclosures required by lizards, space should not be skimped on. Both Wagner and deVosjoli et al recommend about 4-6 ft in length (dependent on subspecies) and 2 ft in width. (This corresponds to the "two thirds" rule of thumb for snakes, ie usually snakes need a minimum length of enclosure two thirds the length of their own bodies). While none of the authors mention a specific height for adults, deVosjoli suggests 15-24" for young snakes, which suggests a height of enclosure of at least 4 ft for adults. Boa constrictors are primarily arboreal, so the use of diagonally sloping strong branches or shelves fixed higher up the wall of the cage is strongly encouraged to allow them to behave naturally (ie climb and coil up above the ground).
As boas are generally from tropical or subtropical areas, heat should be fairly constant with a basking spot. DeVosjoli et al recommend a background temperature of about 80-85 deg F, with 25-30% of the enclosure at one end maintaining a daytime temperature of about 95 deg F.
Humidity is another important factor. The use of large water bowls is suggested as a way of keeping up the humidity in the enclosure, with extra spraying or reduced (but not restricted) ventilation as necessary. Wagner notes that Boa constrictor does not need as much humidity as Epicrates, however. Insufficient humidity most commonly manifests itself in shedding problems in the snake.

To reiterate, if you wish to keep a boa, do buy a good book which will give you more care details than is possible for us to cover on this page (at least without plagiarism!).

Although Kluge (1991) placed the Madagascar Ground Boas (Acrantophis madagascariensis and Sanzinia madagascariensis) and Dumeril's Boa (Acrantophis dumerili) into the genus Boa, we have placed them elsewhere on this site under the old names. This was partly because not everybody has accepted this change, and partly for the more pragmatic reason that we wanted this page to deal simply with Boa constrictor.

Species	Common Name	Origin	Adult size	Notes
Boa
B. constrictor constrictor	Red-Tailed Boa Constrictor	South America E of Andes mtns (E Ecuador, N & E Peru, N Bolivia, N Brazil, C & E Colombia, Venezuela, Guyanas and Trinidad & Tobago	12-14'	Red-Tailed Boa Constrictors are amongst the most beautiful of the species, and hence often sought after and expensive. These are also the largest of the boas, although 9-10' is a more usual size (Wagner). Scales across body: 89-95. Ventral scales: 234-250. Subcaudal scales: ? Brood size: ?.
B. constrictor constrictor	Guyana Red-Tailed Boa	Guyana	?'	?
B. c. amarali	Short-Tailed/Bolivian Boa Constrictor	E Bolivia, Paraguay, Brazil	7'	Not as commonly available. Adults are usually less than the maximum size shown here. The subspecies is intermediate in scale and saddle counts between B. c. imperator and B. c. occidentalis. Scales across body: ?. Ventral scales: 226-237. Subcaudal scales: ?. Brood size: ?.
B. c. imperator	Common Boa Constrictor	Mexico, C America, NW & W Colombia, W Ecuador and NW Peru	6-9'	One of the easiest boas to keep and breed. Scales across body: 55-79. Ventral scales: ?. Subcaudal scales: ?. Brood size: 50+, average 20-30.
	Colombian Boa Constrictor	S America W of Andes	7'	Not to be confused with the Colombian Red-Tailed Boa Constrictor, B. c. constrictor (deVosjoli). Scales across body: 80-84?. Ventral scales: ?. Subcaudal scales: ?. Brood size: ?.
	Hog Island Boa Constrictor	Caya de los Conchinos, Honduras	7', avg max 6'	This insular form is characterised by its smaller size, reduced amounts of dark pigment and often an orange coloration [deVosjoli], which in some specimens may turn pale to almost white [Both]. In the wild it is rumoured to be critically endangered if not already extinct owing to the influx of dogs on the island. Scales across body: 55-79. Ventral scales: ?. Subcaudal scales: ?. Brood size: ?.
	Corn Island Boa Constrictor	Nicaragua	4'	Dwarf form found on island off Nicaragua. Scales across body: 55-79. Ventral scales: ?. Subcaudal scales: ?. Brood size: ?.
B. c. longicauda	Peruvian Black-Tailed Boa Constrictor	N Peru (Tumbes province)	?'	[]
B. c. melanogaster	Ecuadorian Black-Bellied Boa	E Ecuador	?'	Now usually recognised as a phase rather than subspecies. It is found in the Amazon rainforest.
B. c. mexicana	Mexican Boa	Mexico	6-9?'	Subspecies status disputed, some considering this to be merely a phase of B. c. constrictor. Reported to have nastier disposition than B. c. constrictor.
B. c. nebulosus	Clouded Boa	Dominica	6-9?'	Reputed to have poor (nasty) disposition.
B. c. occidentalis	Argentine Boa Constrictor	Argentina, SE Bolivia, Paraguay	7-9' (avg 7' (m), 9' (f))	An attractive but endangered boa which should only be available as captive-bred: as at 1999 this subspecies was listed under CITES I. Wild individuals are also more aggressive than other subspecies. The coloration is the darkest of any subspecies. Life expectancy may reach 20-30 years [Both]. Scales across body: ?. Ventral scales: 240-251. Subcaudal scales:?. Coloration: variable, but generally dark: some specimens may be nearly black with white splattered throughout, while others may be overall charcoal or dark grey with black and white scales. The normal boa saddles here resemble blotches (28-30, interconnected). Juveniles are lighter but darken with age Brood size: 40+ (Both states a maximun of 65).
B. c. orophias	St Lucia Boa	St Lucia	6-9?'	Distinguished from B. c. imperator by higher number of dorsal blotches.
B. c. ortonii	Peruvian Boa	W of Andes	6-9?'	Now usually recognised as a phase rather than subspecies.
B. c. sabogae	Saboga Island Boa	Saboga Island (Panama)	6-9?'	Reddish-brown pattern distinct from that of B. c. imperator.
B. c. sigma	Tres Marias Boa	Maria Madre Island	6-9?'	[]

Bibliography

The Boa Constrictor Manual, Philippe de Vosjoli, Roger Klingenberg DVM and Jeff Ronne, Advanced Vivarium Systems. DeVosjoli's books are invariably excellent and this one is no exception. This is an expansion of the small booklet which AVS formerly published, but this one also brings in Klingenberg (a vet) to discuss diseases, including the dreaded Inclusive Boid Disease (IBD), and Ronne to discuss breeding. If you are just looking for a book on Boa constrictors themselves, this is probably the one for you.

Boas: A Complete Pet Owner's Manual, Doug Wagner, Barrons, 1996, New York/Hong Kong. Excellent book covering all the boas, including the obscure species unlikely to be seen. Highly recommended.

Red-Tailed Boas, Glenn Drenkowski, TFH, 1994. I have not read this book so cannot comment on it.

Snakes: A Complete Pet Owner's Manual, R D & P Bartlett, Barrons, 1997, New York/Hong Kong. Covers snakes in general but has a good section on the more popular and available boas.

Breeding and Keeping Snakes, Dr Dieter Schmidt (translated by William Charlton), TFH, 1995 (originally published in German under the title Schlangen [Snakes] by Urania-Verlag, Leipzig). Although a more general book inasmuch as it covers other snake families besides the pythons, most books by German herpetoculturists are always worth a look. Schmidt does not cover many of the python species other than the most common or desirable ones, and even here the reader should be aware that some of the species listed are placed under older classifications than Bartlett and Wagner's book (eg the Diamond Python which is now Morelia spilota spilota is here listed as Python spilotus, while the White-Lipped Python Leiopython albertisi is listed as Liasis albertisi, and so on). Nevertheless the book does have some useful sections, including a table "Compilation of Breeding Dates in Pythons", plus Genetics and Hybridisation.

Snakes of the World, Chris Mattison, Blandford, 1986/1992, London. A good book with the only reservation being that applied to Dieter Schmidt's, ie some of the taxonomy/classification is now out of date. See also Mattison's Keeping and Breeding Snakes (Blandford) which is probably more immediately useful to snake keepers.

"Hog Island Boas", Herp Mail, Reptile & Amphibian Hobbyist 5:3, Allen R Both. Gives brief overview of husbandry requirements of this phase in answer to reader query.

"The Argentine Boa (Boa constrictor occidentalis)", Allen R Both, Reptile & Amphibian Hobbyist 5:3, November 1999. Gives details of the subspecies and captive care guidelines.

Links

For an excellent site with taxonomic and subspecies information, visit The Boa Constrictors.

Another excellent site with even more of the above information is Siar Anthranir Reptiles run by Charles R Smith. Charles also has some factual data on the true incidence of attacks by snakes and crocodiles on people, which serve both as a precautionary warning against carelessness but also put the number into perspective when compared to deaths and injuries from other animals.

The Boa constrictor section of the JCVI reptile database is interesting inasmuch as it recognises many "phases" as valid subspecies which are not recognised elsewhere.

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