The Yacare caiman is an ancient creature that lives in central South America, about 10 million of them inhabiting the Brazilian pantanal, in what is possibly the world’s largest single crocodilian population. Although they do eat piranha, the name ‘piranha caiman’ is also used for them because their bottom teeth are easily seen, like those of piranhas. While all crocodilians (crocodiles, alligators, caimans and gharials) eat fish, many focus on certain species. Yacare caimans forage in mats of floating vegetation looking for aquatic snails. They crack open the snail shells with their powerful jaws and the shell fragments are dissolved with their strong stomach acids.
Yacare caimans inhabit central South America, including the countries of northeastern Argentina, southeastern Peru, eastern Bolivia, Uruguay, central/southwest Brazil, and Paraguay. They live in the tropical forests of the Amazon Basin. They live beside slow-moving rivers and streams and in swamps.
Little is known about the social behavior of Yacare caimans. They are fierce predators. To hunt, they lie still in the water, and attack when their prey approaches the shore. Generally, they are solitary animals that congregate during the mating season only. They are nocturnal, being active during the night.
Very little is known about the mating system of Yacare caimans. However, caimans exhibit polygynous behavior. This means that males mate with more than one female during the breeding season. The female builds a mound nest where usually 21-38 eggs are laid. Most eggs are laid at the mid-point of the rainy season. The females guard their nests during the incubation period of 2-3 months. This has, however, been shown to be affected by hunting pressure, as females in areas where there is increased pressure of hunting are more wary and are likely to abandon their nest once eggs have been laid. The eggs hatch in March. Hatchlings are precocious, so must fend for themselves, with little or no care given by their parents.
Illegal hunting in the ‘70s and ‘80s was the main threat for Yacare caimans. Organized poaching (e.g. in Brazil) is still one of the primary threats to their survival, along with habitat destruction.
According to the Animal Corner resource, the total population size of the Yacare caiman is around 100,000 to 200,000 individuals. Currently this species is classified as Least Concern (LC) on the IUCN Red List.