The boa constrictor has a reputation as an immense constrictor of monstrous size and habits. It reality, it is a moderate sized animal, certainly nowhere near the size of some of its giant relatives. It is a wide spread, mid sized boid, which can be found in habitats ranging from deserts and savannas to lush tropical rainforest. It ranges throughout South and Central America, from Argentina to Mexico. It is large bodied and muscular, with a tan-brown ground color and dark brown saddles.
Boa constrictors feed on a wide variety of birds, lizards and small mammals, including rodents, bats, and opposums. They often ambush their prey from overhead, coiled about a tree branch waiting for a victim to stroll by. They also take flying birds and bats in this fashion. However, they are also capable ground hunters - their patterns conceal the snake well against fallen leaves or dried grass. Hunting is generally done by the boa's heat sense and smell, although sight is used for the final targeting strike.
Boa constrictors are entirely beneficial to humans. They consume large quantities of pestiferous rodents, and they generate income through their sale into the pet trade. As pets, they are docile and hardy. They reach impressive sizes for a snake, but not too large to be dangerous or unwieldy or unusually difficult to keep. For this reason boa constrictors have become enormously popular captives, and are among the most commonly kept boids (rivaled only by the royal or ball python, a serpent too small and restricted in range to be described in these pages).
The size of adult boas depends on the food supply and temperature, as well as on the population from which they came. Typical male boas reach Medium size, while typical females become Large. The largest boas can be found in the Amazon basin, truely exceptional individuals from that location can become Giant. Boas from islands or from the extreme Northern and Southern parts of their natural range may only reach Small size as adults.