(Common Northern Boa)
The Boa Constrictor Imperator is wide-ranging, with animals living in both Central America and northern parts of South America. As a result, the appearance of this snake varies greatly depending on the specific locality. One population on the Boa Constrictor Imperator is found on the Cayos Cochinos (Hog Islands) off the north shore of Honduras. These are naturally hypomelanistic, which means that they have reduced melanin, and are thus more lightly colored, although they retain the distinctive darker tail that is characteristic of most members of this species. The color of the tail may vary from salmon pink to orange.
Another well known population of Boa constrictor imperator is the population from Nicaragua. While not as small as the dwarf insular island populations, adults are still smaller than the larger Boa constrictor constrictor. The size of a mature female Nicaraguan boa is 1.1 meters (3.6 feet) and 1,900 grams, while the larger female Boa constrictor constrictor is not mature until it reaches 1.6 meters (5.2 feet) and 4,500 grams. Nicaraguan individuals typically have a compact saddle pattern on their back that is often circular in shape. These boas have a reputation for being "nippy", with some individuals being quick to bite in self-defense.
Mainland specimens from Colombia can be among the larger boas, but this subspecies also includes a number of dwarf insular populations, such as those from various Caribbean islands and the Sonoran Desert of Mexico. These populations represent the smallest of the species.
In the wild, prey includes a wide variety of small to medium-sized mammals and birds. The bulk of their diet consists of rodents, but larger lizards and mammals as big as ocelots are also reported to have been consumed. Young boa constrictors eat small mice, birds, bats, lizards, and amphibians. The size of the prey item increases as they get older and larger. Boa constrictors are ambush predators, so often lie in wait for an appropriate prey to come along, when they attack. However, they have also been known to actively hunt, particularly in regions with a low concentration of suitable prey, and this behaviour generally occurs at night. 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.
The Boa Constrictor Imperator subspecies has become extremely popular in the exotic pet trade, due in part to the vast amounts of color and pattern morphs that breeders are creating, as well as their manageable size in comparison to the B. c. Constrictor. Recently, experienced boa keepers have come to the conclusion that boa constrictors do better in PVC, or wooden enclosures, opposed to glass tanks. This makes humidity and heat much easier to maintain, as well as providing a sense of security for the snake. The minimum size is 4 feet long x 2 feet wide and 2 feet high, although a length of 6 feet is much more suitable. It is generally known that all of the Boa constrictor subspecies be fed rats, as an alternative to mice for healthier growth . Typically these snakes are very well tempered and easy to breed. Although, not as thick-bodied as ball pythons, they do, on average, get longer and have a stronger feeding response in comparison to ball pythons.
Boa constrictors are ovoviviparous, giving birth to live young. They generally breed in the dry season—between April and August—and are polygynous, thus males may mate with multiple females. Half of all females breed in a given year, and a larger percentage of males actively attempt to locate a mate. 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. Reproduction in boas is almost exclusively sexual. Males ordinarily have a ZZ pair of sex determining chromosomes, and females a ZW pair. In 2010, a boa constrictor was shown to have reproduced asexually via parthenogenesis. The Colombian Rainbow boa, Epicrates maurus was found to reproduce by facultative parthenogenesis resulting in production of WW female progeny. The WW females were likely produced by terminal automixis, 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.
During the breeding season, the female boa emits a scent from her cloaca to attract males, which may then wrestle for the right to breed with her. 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 few-week period. After this period, ovulation may not occur immediately, but the female can hold the sperm inside her for up to one year. When the female ovulates, a midbody swell can be noticed that appears similar to the snake having eaten a large meal. The female then sheds two to three weeks after ovulation, in what is known as a postovulation shed which lasts another 2–3 weeks, which is longer than a normal shed. The gestation period, which is counted from the postovulation shed, is around 100–120 days. The female then gives birth to young that average 15–20 inches (38–51 cm) in length. 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 6–10 feet (1.8–3.0 m), although they continue to grow at a slow rate for the rest of their lives. At this point, they shed less frequently, about every 2–4 months