I have been buried in books all day, which is not the worst way to spend a Sunday. But then I remembered that there are crocodilians to write about!
The Black Caiman (Melanosuchus niger) is the largest extant member of the family Alligatoridae, and can be found mostly in the Amazon basin in South America, as well as a few other freshwater habitats. It's the largest predator in the Amazon, an apex predator that is potentially capable of preying on any other animal that lives there (including, rarely, humans). It may also be a keystone species, which means that it plays a crucial role in keeping the ecosystem healthy. It was hunted heavily up until the 1980s for its hide, and very little was known about these animals until it was nearly too late to study them.
The average size of an adult male Black Caiman is 9 to 14 feet (2.8 to 4.25 meters) in total length and weigh about 660 pounds (300 kg), though very old males have been measured at longer than 16 feet (5 meters) and weighed more than 880 pounds (400 kg). Females are smaller, averaging 8 to 11 feet (2.5 to 3.35 meters) in length and weighing about 220 pounds (100 kg). Their growth process is similar to that of the American Alligator, but they are larger at the point they reach maturity and are more likely to gain in size from there. Specimens at the top end of the average scale are regularly reported in the Araguaia River, with unconfirmed sightings of even larger animals are rumored as well.
The diet of the Black Caiman depends on what's available, and what size it happens to be at the time. Adults will eat snakes, turtles, birds and a variety of mammals, which include both wild and domesticated animals. In areas where large herds of capybara can be found, they are a favorite prey item for the Black Caiman. More than other caimans, the Black Caiman will actually hunt on land at night, using its strong senses of sight and hearing to locate prey. If a Black Caiman takes prey too large to be swallowed whole after it has been drowned, the caiman will store it underwater until the flesh decomposes enough for the caiman to take bites - their teeth are made for grabbing and holding, not for biting and chewing.
Towards the end of the dry season, female Black Caimans will prepare for mating by constructing nests on the riverbanks, made of vegetation and soil. Depending on the size and age of the expectant mother, she will lay 30 to 60 eggs in the nest and stay nearby for six weeks while the eggs incubate. There are a number of animals that like to feed on these eggs and the young hatchlings, so the mother will take them into her mouth and bring them to the safer portions of the river. Little Black Caimans are independent, though, and most pay a heavy price for leaving their mother's care.
From the 1950s to 1970s, the Black Caiman was hunted for its hide and flesh, to the point where it was declared an endangered species. It is still hunted today, but on a much smaller scale, and this has allowed the population to rebound. They still face the threat of habitat destruction, however, with development and deforestation running rampant in South America. In many places where they were once the dominant predator, they have been supplanted by the more common spectacled caiman.