Boa Constrictor: Profile and Information

Boa Constrictor

The boa constrictor also referred to as the common boa or the red-tailed boa, is a species of large, non-venomous, heavy-bodied snake that is mostly kept and bred in captivity.

The boa constrictor is a well-known member of the Boidae family, mostly found in tropical South America, as well as some Caribbean islands.

Its colour pattern is highly variable and recognizable, a hallmark of private collections and public displays.

While some of these are contentious, nine subspecies are currently recognised.

Scientific classification

Scientific NameBoa constrictor


Amaral’s boa (B. c. amarali)Bolivia, Brazil, and Paraguay.
red-tailed boa (B. c. constrictor)South America
Peruvian long-tailed boa (B. c. longicauda)northern Peru
Ecuadorian boa (B. c. melanogaster)Ecuador
Argentine boa (B. c. occidentalis)Argentina and Praguay.
Orton’s boa (B. c. ortonii)South America
Pearl Island boa (B. c. sabogae)“Pearl Islands” off the coast of Panama


The boa constrictor is a large snake, but compared to other large snakes, such as the reticulated python, Burmese python, or the sometimes sympatric green anaconda, it is only modestly scaled and can reach lengths of 0.91 to 3.96 m (3 to 13 ft) depending on the location and the availability of suitable prey.

The species exhibits strong sexual dimorphism, with females usually being larger in both girth and length than males.

The normal size of mature female boas is between 2.1 and 3.0 m (7 and 10 ft), while males are 1.8 and 2.4 m (6 and 8 ft).

Females usually exceed 3.0 m (10 ft), especially in captivity, where lengths of up to 3.7 m (12 ft) or even 4.3 m (14 ft) can be seen.

At the Zoologische Staatssammlung München (ZSM 4961/2012), the largest recorded non-stretched dry skin is stored and measures 14.6 ft (14.3 m).

The boa constrictor is considered a heavy-bodied snake and can weigh up to 60 lb (27 kg) (large specimens).

Generally, females, the larger sex, can weigh 22 to 33 lb (10 to 15 kg). Some Individuals of this species can reach or exceed 100 lb (45 kg), although this is not customary.

A boa constrictor’s size and weight depends on the subspecies, availability of suitable prey, and locale. B. c. Constrictor meets the averages given above and sometimes tops them, as it is one of the relatively large Boa constrictor subspecies.


Boa imperator has 50 to 95 dorsal scales, 223 to 252 ventral scales, 43 to 69 subcaudal scales, 19 to 25 supralabial scales, and 1 to 3 anal scales.


The colouring of boa constrictors can vary greatly depending on the locality. In general, they have a brown, grey, or cream base colour, patterned with “saddles” of brown or reddish-brown that becomes more pronounced towards the tail.

This colouring gives the B. constrictor species the common name of the “red-tailed boas.”

There are pigment defects in some specimen, such as albinism. While these specimens are uncommon in the wild, in captivity they are common, where they are often selectively bred to produce a range of “morphs” of different colours.

The arrow-shaped head of the Boa constrictors has very distinctive stripes on it: one extends from the snout to the back of the head dorsally; the other runs from the snout to the eyes and then from the eyes to the jaw.


Boa constrictors usually live on their own and unless they wish to mate, do not associate with any other snakes.

They are nocturnal, but when night-time temperatures are too low, they may bask during the day.

Young boa constrictors can climb into trees and shrubs to forage as semi-arboreal snakes; however, they become more terrestrial as they become older and heavier.

When they perceive a threat, Boa constrictors strike. Their bites, particularly from large snakes, can be painful, but they are rarely harmful to humans.

Boa constrictors are more unstable in a shed cycle, like all snakes, since the material that lubricates between the old skin and the new makes their eyes look milky.

Their eyes may also appear blue, or opaque so that the snake cannot see very well, making them more defensive than they usually are.


Boa Constrictor

The boa constrictor is viviparous, giving birth to live offspring. They usually breed between April and August (dry season) and are polygynous; with males mating with multiple females.

In a given year, half of all females breed, and a greater percentage of males actively try to find a mate. Many of these males would be ineffective due to their polygynous nature.

As such, if they do mate, female boas are unlikely to attempt to mate in poor physical health or to produce viable young people. Reproduction is almost exclusively sexual in boas.

Terminal automixis, a type of parthenogenesis in which two terminal haploid meiosis products fuse to form a zygote, which then develops into a daughter progeny, was probably developed by the WW females.

This is the third genetically confirmed case of successive virgin births of viable offspring within any vertebrate lineage from a single female.

Males were found to contain a pair of chromosomes defining the XY sex, while females have a pair of XX.

The female boa releases pheromones from her cloaca during the breeding season to attract males, which will then wrestle to pick one to breed with her.

The male coils his tail around the female during breeding and the hemipenes (or male reproductive organs) are inserted.

Copulation may last from a few minutes to several hours and can occur multiple times over a period of a few weeks.

Ovulation may not occur immediately after this period, but the female may keep the sperm within for up to one year.

The female sheds 2 to 3 weeks after ovulation, which is referred to as a post-ovulation shed, and it lasts for another two to three weeks.

The gestation period counted from the postovulation shed is approximately 100 to 120 days. The female then gives birth to offspring with an average length of 38 to 51 cm (15 to 20 in).

The litter size varies between females but can be between 10 and 65 offspring, with an average of 25, although some of the young eggs may be unfertilized or stillborn (also known as slugs).

At birth, the offspring are independent and develop rapidly for the first few years, shedding frequently (once every 1 to 2 months).

Boa constrictors become sexually mature at 3 to 4 years and reach 1.8 to 3.0 m (6 to 10 feet) in adult size, although they continue to grow for the rest of their lives at a slow rate.

At this point, they shed less regularly, about every 2 to 4 months.

Hunting and diet

A wide range of small to medium-sized mammals and birds are included in their prey. The majority of their diet consists of rodents, but they are also known to eat larger lizards and mammals as large as ocelots.

Young boa constrictors eat small mice, birds, bats, lizards, and amphibians. As they grow older and bigger, the size of the prey item also increases.

Boa constrictors are ambush hunters, so they often lie in wait for suitable prey to come along then strike.

First, the boa hits the prey, grabbing it with his teeth; then before swallowing it whole, it continues to constrict the prey until death.

Instead of suffocation as previously thought, unconsciousness and death are likely to result from cutting off critical blood flow to the heart and brain; constriction will interfere with blood flow and overwhelm the normal blood pressure and circulation of the prey.

This can quickly lead to unconsciousness and death. Their teeth also help push the animal down the throat and then move it towards the stomach with the aid of muscles.

Depending on the size of the prey and the local temperature, it takes the snake about 4 to 6 days to completely digest the food. After eating, the snake might not feed for a week or even for several months due to its slow metabolism.

Distribution and Habitat

Boa constrictor can be found north of 35 ° S in South America (Colombia, Ecuador, Guyana, Suriname, Peru, Venezuela, Trinidad and Tobago, French Guiana, Brazil, Bolivia, Uruguay, and Argentina) and several other islands along the coasts of South America, depending on the subspecies.

B. constrictor, in a wide range of environmental conditions, from tropical rainforests to arid semi-desert countries, flourishes.

But, due to temperature and humidity, natural protection from predators, and large quantities of potential prey, it tends to live in the rainforest.

It is often found in streams and rivers or close to them, as it is a very good swimmer. The burrows of medium-sized mammals are also inhabited by Boa constrictors, where they can hide from possible predators.


Notify of

Inline Feedbacks
View all comments
You May Also Like