Boa Constrictor

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PetMD Editorial
Published: January 18, 2016

Popular Varieties

This is one of the few instances where an animal’s scientific name is the same as its common name. There are six subspecies currently recognized by all herpetologists, including the Common Boa Constrictor, Red-Tailed Boa Constrictor, Clouded Boa Constrictor, San Lucia Boa Constrictor, Short-Tailed Boa Constrictor, and Argentine Boa Constrictor.

Boa Constrictor Size

Boas are one of the few snakes that produce live births, versus eggs that need to be incubated. Newborn boa constrictors range in length between 14 and 22 inches and weigh just 2 to 3 ounces. The average adult size ranges from 4 to 7 feet in length, with some individuals occasionally reaching 8 or 9 feet in length.

Male boa constrictors tend to be a little smaller than females. Most captive-bred boa constrictors do not exceed a weight of 60 pounds, with most subspecies topping out at around 30 pounds. The largest boa constrictor on record is believed to have been 14 feet in length.

Boa Constrictor Lifespan

Boa constrictors are among the longest-lived snake species in the world. It’s quite normal for a boa constrictor to live for twenty to thirty years or more. In fact, the oldest recorded boa lived to be just over forty-three and lived at the Philadelphia Zoological Gardens.

Boa Constrictor Appearance

Boas are primitive snakes, just like pythons. They have vestigial remnants of the pelvis and hind limbs of their lizard-like predecessors. A boa’s small cloacal spurs on the sides of its vent (anus) are actually connected to said vestigial limbs!

Boa constrictors have distinctive and varied markings. Depending on the habitat they’re trying to blend into, boas can have a range of colors, including tan, green, red, and yellow. They typically have blotches on their tails and scale patterns that look like leaves, ovals, diamonds, or circles.

Depending on the subspecies, your boa can take on a variety of looks.

Common Boa Constrictors

The common boas have less than 253 ventral (belly surface) scales and at least 21 dorsal (top surface) blotches (the area between the vent and the neck). Common boas don’t have speckled bellies, but if they do they are lightly speckled and the pattern on the tail appears to be smudged. There are quite a few different color and pattern varieties created by breeders, one of the most popular being the scarlet Blood Phase Boa.

The Red-Tailed Boa

This is the most popular boa subspecies, with a greater number of ventral scales (234–250) and blotches. They have black speckled bellies and defined red blotches on the surface of their posterior and tail, thus the name. Red-Tailed Boas are the largest subspecies of boa and are arguably the most beautiful.

Short-Tailed Boas

Short-tailed Boas have between 226 and 237 ventral scales, twenty-two dorsal blotches, and heavily speckled dark bellies. They have flatter-looking heads and a background color that ranges from gray and silver to a rich, dusky yellow.

Peruvian Black-Tailed Boas

This is a distinct morph (morph is variety created by breeders and not found in the wild) with a wide, central head stripe and black anterior and posterior facial markings. It has dark, interconnected saddling on a background color that ranges from yellow-brown to light powder-gray, with copious amounts of black throughout. Both the posterior body and tail blotches are black, thus the name. There are very few of this type of boa in existence.

Argentine Boa Constrictors

Argentine's have between 242 and 251 ventral scales, 29-30 interconnected dorsal blotches, and black and white peppering.

Boa Constrictor Care Level

Both the Common boa and the Colombian boa make great pets for herpetoculturists. Due to their large size and longer-than-average lifespan, boa constrictors are recommended for intermediate and advanced snake keepers.

Boa Constrictor Diet

Shortly after it’s first shed, a boa constrictor will begin to eat. Boas are some of the best eaters in the reptile world and rarely present feeding problems. They usually will eat both live and pre-killed food, though we always recommend feeding your snake pre-killed food to avoid injury.

A boa constrictor’s growth is directly related to its feeding regimen, with the majority of growth achieved during the animal’s first two years. After hitting sexual maturity, a boa’s growth will slow down.

When feeding your pet snake it’s important to provide appropriately sized meals. An appropriately sized prey animal’s girth should not exceed the girth of your snake at mid-body. Feeding a snake prey that is too large can result in regurgitation and internal injury to the snake.

Unless you’re raising your boa to breed, or have a feeding regimen in mind already, this standard boa constrictor feeding regimen can be used successfully:

  • From hatchling to 3 feet: feed one to two appropriately sized mice every week.
  • From 3 to 6 feet: feed one to two appropriately sized rats every seven to ten days, or every two weeks for a reduced growth rate.
  • From 6 feet on: feed one to two appropriately sized rabbits every ten to fourteen days.

Safe Feeding Tips

When feeding your boa live prey, always keep an eye on it and remove the prey animal if the boa isn’t hungry. A scared prey animal can claw and scratch your boa, causing injury and infection. Always feed one snake per enclosure at a time to avoid injury to yourself and the other snakes.

It is also a good idea to feed your snake in a separate feeding tank so they don’t associate feeding with their “home” set-up.

One common feeding practice among snake owners is to “power feed” snakes by feeding them large amounts of food towards the beginning of their lives. The idea is to taper off the amounts of food given as they grow, resulting in an optimal size.

However, power feeding is NOT good for boa constrictors and is not recommended. Boa constrictors tend to grow slower and metabolize their food slower than other snakes. Overfeeding a boa can result in digestive problems, obesity, and regurgitation, particularly in Argentine and Red-Tailed Boas.

Boa Constrictor Health

Common Health Issues in Boa Constrictors

Any pet, whether reptile or mammal, will likely have health concerns at some point in their lives. The following is a short summary of Boa Constrictor diseases and disorders. 

Inclusion Body Disease

Boa constrictors, while typically a healthy and hardy animal, are susceptible to one serious disease in particular: Inclusion Body Disease (IBD), which is a fatal retrovirus much like AIDS in humans (this disease is not transmissible from humans to reptiles or vice versa). Boa constrictors are recognized as the main carriers of IBD, but the disease may lay dormant (no clinical signs) in them for months or even years.

Never keep your boas in the same enclosure as other types of boid snakes (like pythons) or you risk transmitting the deadly disease to them. At this point, professionals believe IBD only affects boid snakes.

Transmission of IBD can occur when a boa has mites and the mites transfer infected body fluids to other snakes during breeding or cohabitation. A great way to avoid this is by always housing your boa constrictors in different cages from any other boid snakes you may own.

Early signs of IBD can include your boa breathing with its mouth open, excreting lots of thick saliva, and having a low appetite. The symptoms of early stage IBD mimic those of the more common reptile respiratory infection, so it’s important that you seek the help of an experienced herp veterinarian as soon as you notice any symptoms.

During the more advanced stages of IBD, snakes will lose control of their movements, their ability to right themselves, and they’ll display a contorted appearance called “stargazing syndrome” where they appear to be looking and moving upside down.

Respiratory Infections

Aside from IBD, reptile respiratory disease is another problem to be on the lookout for. Thankfully, most reptile respiratory diseases are caused by inadequate heat gradients or poor husbandry practices and can be easily remedied.

If you notice your boa is wheezing while breathing or displaying other signs of a respiratory infection, like holding its head up for extended periods of time, check the temperatures in its enclosure. Sometimes all it takes is more heat to cure a respiratory infection, but seek professional advice if your snake is experiencing labored breathing, nasal discharge, or loss of appetite.

More advanced cases of pneumonia will have your boa secreting a foamy, cheese-like substance from its mouth and throat region. If you notice this secretion, take your snake to the vet at once.

Scale Rot (Necrotizing Dermatitis) and Blister Disease

These two conditions often appear together and are almost always a result of sub-standard husbandry practices.

The main cause of blister disease is too much heat or inappropriate humidity, while scale rot is caused mainly by a breakdown of the immune system. Scale infections in boas can have a variety of symptoms ranging in severity, from mild hemorrhaging to severe blistering and ulceration.

In the worst cases, it will look like your boa has chemical burns; these can take several weeks to completely heal. With any skin disease, seek veterinary care from a reptile specialist.

Boa Constrictor Behavior

Depending on their subspecies, captive-bred boa constrictors are known for being well-tempered, docile creatures.

Colombian boa constrictors are some of the most docile, while imported Mexican and Central American boas tend to be a bit more aggressive. When properly handled and maintained, boa constrictors make relatively safe pets. Boa constrictors will bite if they feel threatened, and a bite coming from a large snake can hurt quite a bit.

Always give your boa 24 hours to properly digest its food after a meal before handling it so it doesn’t regurgitate its food—or worse, bite you.

An established handling routine of two to three times per week should be enough to help improve a nervous boa’s disposition. For the most part, with time and regular interaction, almost every boa constrictor will settle down.

Supplies for the Boa Constrictor’s Environment

Aquarium Tank or Terrarium Setup — Building a Boa Habitat

The main concern when choosing an enclosure for your pet boa constrictor is that it has a secure locking mechanism. It is never OK to assume your boa is secure by laying wood boards or books on top of the cage and weighing them down.

Many boa owners favor glass enclosures with sliding glass fronts or screen tops. The size cage you’ll need depends on the species and size of your boa. For instance, baby boas need an enclosure that’s 36 inches long and 15 to 24 inches tall. Most adult boas require an enclosure at least 6 feet long, but smaller varieties, like the Hog Island Boa and small male boas, can live happily in a 4-foot enclosure.

When it comes to the substrate (bedding) used for boa constrictor enclosures, the most popular choice is newspaper. It’s cheap, easy to replace, and readily available. The downside is that newspaper can be ugly, especially if you want to maintain a naturalistic snake enclosure.

More aesthetically pleasing options for substrate include aspen shavings, reptile bark, or pine shavings. Or, you can even use soil (minus any fertilizer or perlite) for a more natural look that absorbs odor and liquids. Soil substrate is a good option because you can replace it in sections. Add a layer of leafs on top for an even more authentic look.

Boas are found living near rivers and lakes in the wild, so including a large water bowl for drinking, periodic soaking, and bathing is a great idea. Be aware that boas tend to defecate in large pools of water, however, so whatever size bowl or pool you choose, just make sure it’ll be easy to clean up.

Branches and Shelters for Boas

Boas like to hide. If they don’t have somewhere to escape to and relax, they can get stressed and sick. Boas are also arboreal in the wild and enjoy climbing trees and wrapping around branches. Get the best of both worlds by providing a ground level shelter out of a wood hollow or cork log and then introduce an easy to climb branch that slopes across the length of the enclosure.

For the shelter, make sure it is slightly taller than the mid-body diameter of your snake. You can also create a shelter that rests on a shelf above the ground, but if you choose to do so make sure it’s anchored with screws and/or angle irons to support your snake’s full weight and prevent collapse and possible injury.

The climbing branch should be sturdy enough to support the snake’s weight and have a few forks in it and a nook area about halfway down the length of the branch.

Heat and Light

Boa constrictors do not require extra lighting as long as there’s a bit of natural light coming into the room in which they’re kept. What they do need is a proper thermal gradient so that they can regulate their own body temperature (thermoregulation).

To create a heat gradient, you’ll need two to three electronic thermometers (we recommend using digital ones with external probes) to monitor the temperature at each area of the habitat, a background or air temperature between 80-80 degrees Fahrenheit (a nighttime temperature of 78 degrees Fahrenheit is acceptable), and a “hot spot” of 95 degrees Fahrenheit (plus or minus 5 degrees when calibrated at the surface).

If you’re using an enclosure with a screen top, be aware that a lot of the background heat will escape, so you may need to place an overhead ceramic heat emitter or incandescent bulb and reflector above it.

To make an ideal hot spot in your boa enclosure you can choose from three methods:

  1. Sub-tank heating units can be placed under 2/3 of the tank, or heat tape/strips, like Flexwatt or Cobra heat mats, can be affixed under glass tanks or even incorporated in the floor of custom enclosures.
  2. In-tank heating units are some of the simplest ways to create hot spots. Simply buy a heat-generating pad made for reptiles and place it inside the enclosure, taking care to cover no more than 30 percent of the floor area.
  3. Incandescent and infrared bulbs or ceramic heat emitters can also be used to provide a basking area. If choosing an in-cage heating option, always make sure the bulb is enclosed in a protective wire basket to prevent your snake from burning itself.
  4. With any plug-in heat source, be safe and make sure that the heat is not against a surface that can burn or catch fire. Some of these bulbs get very hot, and if they break, glass could enter the tank and cause injury to your snake.

Boa Constrictor Habitat and History

Boa constrictors have an expansive distribution, ranging south from Mexico through Central and South America to Argentina, as well as in the Lesser Antilles islands of Dominica and St. Lucia, on San Andres, and in many of the small islands dotting the Mexican and Central/South American coast.

Boa constrictors tend to prefer the tropical climates of rainforests, but they can thrive in various conditions, ranging from the tropics to arid deserts, depending on the species.

Boas are adept swimmers but prefer to hide in trees or in the burrows (holes dug into the ground) of small mammals, where they can wait for their prey.

Boas have been harvested for many years for their meat and skins, but didn’t start becoming popular as pets in America until 1977. They’re the snake breed most commonly killed to make products, second only to the reticulated python.

All boa constrictors fall under the Washington Convention (a treaty protecting endangered plants and animals) and are subject to strict regulation if transported internationally.

This article was verified and edited for accuracy by Dr. Adam Denish, VMD.