skilled tree climbers and often prey on bats. They range
from Central America all the way south to Patagonia.
Perhaps the best known of the group is the Boa
Constrictor (Boa constrictor; plate 16- 72), common
throughout the Neotropics. Boa Constrictors are warm
tan, with dark brown, diamond- shaped patterning, but
variable in color pattern. Those found in South America
are generally lighter- colored and more sharply marked
than their Central American counterparts. Their heads,
like those of all Boidae species, are long and taper to a
pointed snout. Boas average about 1.5 to 1.8 m (5– 6 ft)
in length. The largest Boa Constrictor on record was
5.64 m (18.5 ft), most extraordinary for this species.
Boas can be aggressive and will coil, hiss, and bite if
attacked. In captivity they can become docile (but they
don’t belong in captivity, regardless of disposition).
They are mostly nocturnal, feeding on all manner of
mammals, including small cats. They also take birds
and lizards. Boa Constrictors inhabit a wide range of
habitats, from wet lowland forests to dry savanna.
The Emerald Tree Boa (Corallus canina) is one of
the most beautiful of Neotropical boids. Deep green
above, yellow green below, with a dorsal white line and
scattered white spots, it has burning yellow eyes with
catlike, slitted pupils. Confined to South America, this
1.8 m (6 ft) boa can be cryptic, said to resemble a bunch
of bananas when coiled in a tree. Small individuals
have been found on banana boats among the bunches.
The tail is prehensile, and these snakes are skilled
at moving about in the trees, preying on squirrels,
opossums, birds, and lizards. Both the Emerald Tree
Boa and Boa Constrictor become tame when handled
frequently by humans.
The largest of the Neotropical constrictors is the
Green Anaconda (Eunectes murinus), most common
along rivers and in marshes (discussed in chapter 12).A Few More Nonvenomous Snakes
There are many additional species of nonvenomous
snakes in the Neotropics. They include the various vine
snakes (genus Oxybelis), thin brown, gray, or green
snakes that climb about the foliage capturing and feeding
on lizards. The beautiful Indigo Snake (Drymarchon
corais) can reach lengths of 3 m (9.8 ft), eating virtually
any kind of animal from fish to birds. The large- eyed,
extraordinarily thin Blunthead Tree Snake (Imantodes
cenchoa; plate 16- 73) may be spotted coiling in outer
branches, where it preys on small tree frogs and lizards.Plate 16- 71. The Rainbow Boa (Epicrates cenchria) is one of
the most beautifully patterned of the boas. It occurs in both
Central and South America. Photo by Sean Williams.Plate 16- 72. Boa Constrictor. Photo by James Adams.Plate 16- 73. The Blunthead Tree Snake is a common
nonvenomous snake species ranging from Mexico through
Amazonia. It is typically encountered in understory
vegetation. Photo by Dennis Paulson.chapter 16 from monkeys to tarantulas: endless eccentricities 351