APPEARANCE
Like a monster from the age of the dinosaurs, the primitive-looking black caiman (Melanosuchus niger)
inspires fear and dread. Also called jacaré, it could be mistaken for the well-known American alligator and
belongs in the same taxonomic family, Alligatoridae. It is the largest member of the family, ranking among
the biggest crocodilians. It averages 10 to 13 feet (3 to 4 meters) and reaches a maximum 16.5 feet (5 meters).
Indeed, this is the largest predator in South America.
In appearance, the black caiman is characterized by a dark gray to black skin covered in scales (as with all
reptiles), some of which are thickened and raised. The skin color may serve to camouflage the caimain during
nocturnal hunting, while during the day, it helps absorb heat.
A distinctive feature is gray banding across the lower jaw and yellow to beige bands along the sides. These
markings fade as the animal ages and may be more or less absent in fully mature adults. Like the spectacled caiman, the black caiman has a bony ridge between the eyes that
extends either side down the snout. In contrast, the black caiman has a relatively narrow snout and large
eyes. The latter feature may be related to its nocturnal feeding habits.
HABITAT AND DISTRIBUTION
The black caimain inhabits remote rivers throughout lowland Amazonia. Its geographic range extends east of
the Andes to the Atlantic, and north of the Brazilian Pantanal to southern Venezuela. Its range overlaps with
that of the spectacled caiman, but the two species occupy quite different ecological niches. The black caiman favors areas along river banks with steep
sides, among entangled roots and fallen branches. Rebelo and Lugli (2001) report that
it prefers deep, fast moving waters. Juveniles are often found on floating mats of vegetation.
FEEDING AND DIET
Such a large animal is, as you might expect, not a fussy eater. The caiman's diet includes fish, birds
and turtles. The majority of the diet is comprised piranhas, catfish and aquatic molluscs. As with other
crocodilians, they ambush terrestrial animals, particularly capybara, but also peccaries and tapir when they drink at riversides or swim across a stream or swamp.
Juveniles feed on small aquatic prey such as freshwater crabs, insects and other invertebrates. As they
grow, the animals graduate to larger prey and sometimes hunt on dry land, mainly at night. Mature
individuals occasionally attack on humans and livestock.
BREEDING
Few details are known of the breeding habits of wild caiman. (Perhaps unsurprisingly considering the
courage needed to study the animal up close in its own domain!) In most respects, it appears similar to
that of other large crocodilians. As the rivers recede and rain falls off during the dry season, the
female caiman looks for a suitable spot, ususally by the side of a slow-moving river or swampy lake. The
site may be out in the open or relatively hidden. Once situated, she shovels leaf litter, twigs and
drying aquatic vegetation to form a large nest about 6 feet across. She then scoops out the center and lays
between 30 and 65 (average 40) eggs in the mound. The eggs are oval-shaped, weighing about 5 ounces (143
g). For 40 to 100 days, she will zealously guard her horde, remaining in the vicinity to fend off egg
predators. Around the beginning of the dry season, the eggs are ready to hatch, whereupon the female
opens the nest, releasing the hatchlings. This is their most vulnerable stage of life.
The female's interest in her offspring remains strong but she cannot protect them all. Often, many
females choose nest locations close together, so if lots of hatchlings emerge together, there is a better
chance at least some of them will escape and grow large enough to be relatively safe. As with other
crocodilians, the gender is determined by temperature within the nest (in contrast to mammals and most
other animals in which gender is determined by chromosomal
arrangements). In turn, nest temperature depends on the heat of decomposing vegetation and exposure
to sunlight.
CONSERVATION
The adult caiman is at the top of the food chain, except for humans who hunt it for food and leather.
The black caiman once teemed throughout the Amazon but hunting greatly reduced numbers and it is now
quite rare, less common than the spectacled caiman whose range overlaps. It is listed in the IUCN Red
Book as Endangered. It remains locally common
in isolated patches but good census data hampers efforts to establish long-term management
programs.
Locals sometimes justify hunting by arguing that caiman eat a large amount of their potential catch, but
scientists found that the favored commercial species (such as tambaqui and pacu comprise
only a small proportion of stomach contents. Economically, the species is most important as a source of
meat and skin.
The hunting technique is simple. Patrol a river bank at night, shining a flashlight into thick banks of
reeds and riverside grasses. The eye of the caiman reflects back red, glowing like a hot coal. The hunter
with a rifle needs only to shoot in the proximity of this target for the chance of a hit. Such an easy
prey and lucrative trade in caiman skins for boots, purses, belts and other leather goods led to the
demise of populations. Although today considered at low risk of extinction, it remains on the endangered
species list.
Efforts are underway to ensure the future of the black caiman. Captive breeding programs combined with
controlled harvest studies suggest that the species is a good candidate for commercial farming. Such an
approach would relieve pressure on wild populations and provide local people with a source of income.
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