black caiman

black caiman, (Melanosuchus niger), large caiman species best known as being the largest predator in the Amazon River basin and the largest member of the alligator family (Alligatoridae). The species is found in wetlands, flooded savannas, rivers, and other freshwater environments in northern South America, from eastern Ecuador eastward to southeastern Colombia, Guyana, French Guiana, and northern Brazil and southward through eastern Peru, northern Bolivia, and central Brazil.

Natural history

Most adults are massive individuals, measuring between 4 and 5 meters (13 and 16 feet) in length and roughly 350 kg (770 pounds) in weight; indeed, some exceptionally large black caimans have grown to a length of 6 meters (20 feet). The caiman’s body coloration ranges from charcoal to black, but it has gray or brown banding on the lower jaw and lighter banding ranging from white to yellow on the tail and body. The species has a long rounded and blunt snout, powerful jaws, short legs with clawed webbed toes, and a long tail. Two ridges of bone on the top of the head taper partway into the snout. The jaws contain 72 to 76 teeth. The juvenile is similar to the adult in appearance, but it has a shorter snout and more-prominent banding.

The black caiman is an apex predator. Even though the geographic range of the species overlaps with other large South American predators, the caiman seems to have its own ecological niche, and thus it has few competitors. It usually basks on steep riverbanks during the day and hunts at night, striking primarily from the water. Adults prefer mollusks and fish, such as catfish and piranhas, but they also consume capybaras, deer, boars, dogs, snakes, and livestock. They are also dangerous to people, and several dozen attacks on people have been reported since 2000. Juveniles prey on smaller items, such as crustaceans and other invertebrates as well as small fish. Although adult black caimans’ formidable size is enough to deter other predators, juveniles may be taken by anacondas and jaguars.

The black caiman is polygynous (that is, the male may mate with several females in a single breeding season). Although less is known about the details of black caiman courtship than is known about that of other crocodilians, ecologists think that the species breeds during the Amazonian dry season, generally between September and December. After fertilization takes place, a female caiman constructs a nest made up of plant material within which she deposits her eggs. It is common for several breeding females to build their nests close to one another. The average clutch size is about 39 eggs, but clutches of up to 65 have been reported. In general, the female remains close to the nest and guards her eggs until they hatch, sometime between 2 and 3 months later to coincide with the onset of the rainy season. She assists her young by breaking open the nest as they emerge from their eggs. The young from other nests emerge at the same time, and the broods of some females may join together in a group (or pod) for mutual protection. The female caiman cares for her young until they go off on their own a few months later. It is thought that black caimans become sexually mature between ages 4 and 10, and some sources note that females breed only in alternate years or every third year. The species can live up to 80 years in the wild and about 13 years in captivity.

Conservation status

The black caiman was hunted intensively for its hide, which was used to make black leather products, for most of the 20th century, and hunting pressure increased during the 1940s and ’50s as the populations of other commercially valuable crocodiles and caimans declined. By the end of the 20th century, black caiman populations had fallen by as much as 99 percent. The International Union for Conservation of Nature and Natural Resources (IUCN) listed the black caiman as an endangered species between 1982 and 1994 before listing it as vulnerable between 1994 and 1996 and re-listing it as endangered in 1996. In 2000, when the last official IUCN population assessment was performed, the organization classified the black caiman as a species of lower risk (a category no longer used by the IUCN). The assessment showed evidence that black caiman populations were increasing and becoming widespread, which suggested that the species was no longer in danger of extinction. Despite the caiman’s success, it continues to be hunted illegally in several countries, and ecologists note that the combination of habitat loss and increased contact and competition with the spectacled caiman (Caiman crocodilus) is becoming an obstacle to the species’ rapid recovery.