Black Caiman (Melanosuchus niger)

The Black Caiman is perhaps the most magnificent of all caimans, with some individuals growing to 5 m or more in length. Adult individuals are easily identified by their completely black dorsal side. Juveniles have about 9 yellow bands across their back. The species is widely distributed within the Amazon basin, and inhabits a variety of habitats, including quiet backwaters, lagoons, lakes and rivers, and tends to avoid strong currents.

Clutches comprise 30-60 eggs, laid in a mound nest. Females remain near the nest and may defend it against potential predators. In Ecuador the majority of nests are built in October; in Bolivia in September-November; Colombia in late November-January and Brazil from mid-August to November.

Small individuals prey on small fish, amphibians and invertebrates, and larger ones feed mainly on capybara (a large rodent) and a variety of other larger mammals, turtles and fish. In Brazil, increasing populations of M. niger have been implicated in some attacks on humans.

The skin of M. niger is considered to be more valuable than that of other caiman species. There has been heavy exploitation of the species, and the wild populations in some Range States have been greatly reduced. Habitat loss (logging and agriculture) has also been detrimental. However, large populations still exist in some areas. For example, the wild M. niger population in Brazil has recently been estimated to exceed 16 million individuals, and a wild harvest program has been initiated there.

 

Broad-snouted Caiman (Caiman latirostris)

Caiman latirostris is a small species restricted to the southern parts of South America, namely Argentina, Brazil, Paraguay and Bolivia. Adults are around 1.5-2.0 m long, although some may reach 3 m. The species inhabits marshes, lagoons and other water bodies, and is considered to be one of the most wary crocodilians. It appears to be more tolerant of cool climates than “tropical” species.

Nesting occurs at different times of the year depending on the region. In Brazil it occurs between August and January, in Uruguay in January, and in Argentina between January and March. An average of 40 eggs is laid in a mound nest. In captivity, the male of a breeding pair has been observed to help the female in the early stages of nest-building, but this has not been documented from the wild. Both eggs and hatchlings are preyed upon by a variety of predators, and large C. latirostris will eat smaller ones, too. The diet consists of a variety of aquatic insects, crustaceans and other invertebrates, particularly snails.

Concern has been expressed that populations are being seriously reduced by uncontrolled hunting and habitat destruction. After Melanosuchus niger (Black Caiman), C. latirostris yields the best skin of all the southern South American caimans. A ranching program that produces skins for the international market has been underway in Argentina for some years - it includes the return of 10- to 12-month-old juveniles back into the wild.

 

Cuvier’s Dwarf Caiman (Paleosuchus palpebrosus)

With an overall length of not more than 1.7 m, P. palpebrosus is probably the smallest of all crocodilians. It is widely distributed throughout the Amazon basin (namely: Eastern Colombia, Venezuela, all Guyana states, Eastern Ecuador, Peru, Northern Brazil, Eastern Bolivia and Northeast Paraguay). In contrast to many other crocodilians, the species prefers fast flowing or torrential rivers. Here, it can often be found sympatric with P. trigonatus, which is commonly more abundant. Occasionally, the caimans can be found in slow flowing rivers, canyons and lagoons.

The reason for the aberrant habitat preference of the species is can be found in the lower temperature preferences of both Paleosuchus species (reportedly much lower than 20°C). They have never been observed basking or in direct sunlight and can usually be found under overhanging trees or bushes.

P. palpebrosus, like all other crocodilians, feeds on a variety of prey including molluscs, insects, fish, amphibians (especially tree frogs), reptiles birds and small mammals. Cannibalistic tendencies have been observed. During hotter times of the day individuals may retreat to small burrows in between tree roots or at the river bank.

Mound-nests are usually built around August. They are found in shaded forests where there is rarely direct sunlight. Temperatures within the nests are kept constant by termites. Hatching takes place in November and December. Females assist hatchlings by opening the nests and carry them to the water; but apart from that care for nests and juveniles is least expressed in this species. Only in captivity the protective behaviour of juveniles and nests, which is usually typical for all crocodilians, could be observed. Interestingly, in nature an unbalanced male-female ratio could be observed. Males were far more abundant than females. This could be found in both hatchlings and adult populations. The reason for it is still unclear.

 

Schneider’s Smooth-fronted Caiman (Paleosuchus trigonatus)

Throughout most of its range P. trigonatus can be found sympatric to P. palpebrosus mostly in narrow jungle creeks and streams. Nevertheless, within these areas the species prefer different ecological niches: While the Dwarf caimans prefer slightly more vegetated and more quiet parts of the river, P. trigonatus is mainly found in or around the strongest flowing parts of the river and seem to tolerate even lower temperatures. It can even be found in small and cold (12-14°C) streams up to altitudes of 1300 m.

Both Paleosuchus species lack the inter-orbital ridge that characterises the other caiman species as well as increased ossification of the skull and other features giving the skull a distinct angular shape.

The caimans do not appear to congregate in large numbers. Males rarely grow longer than 1.7 m and females larger than 1.2 m in length, and they are perhaps the most heavily "armoured" of the world's crocodilians, with large bone deposits in the skin. From a commercial point of view their skin is virtually worthless, so they are perhaps the most "secure" of living crocodilians with regard to hunting pressure.

Small mammals and invertebrates are the preferred food for the species. Individuals are rarely, if ever seen out of water, but radio-tracking indicated that they leave the water at night and remain some distance away from it, presumably to capture prey. Natural predators are larger fish, anacondas, birds and jaguars. Also blood sucking parasites (nematodes) may represent a serious threat to the animals. During the day, sometimes even for days, they may retreat in 3 m long burrows under riverbanks or hollow tree trunks. 

Maturity is usually reached after about 11 years in females and 20 years in males. Like P. palpebrosus, the species constructs its mound nests (10-25 eggs) during the dry season next to termite mounds in shaded jungle areas, in order to gain the additional heat (produced by the termites) to incubate their eggs. The ratio of males:females is skewed in favour to females as a result of low breeding temperatures. Females will protect the nests also in the wild. But within a week or two juveniles will disperse and parental care is offset.

 

Spectacled Caiman (Caiman crocodilus)

Spectacled Caimans are widespread throughout Central and South America, and appear well adapted to surviving in a great variety of habitats, but preferring lakes, ponds, marshes and meandering tributaries of slow moving rivers. They are particularly abundant within some South American countries (e.g. in Venezuela’s populations are estimated to exceed 3 million individuals). Three subspecies of Caiman crocodilus are recognised: C. c. crocodilus, C. c. apoporiensis and C. c. fuscus; but distinguishing them from each other is not easy.

Spectacled caimans are a small crocodilian, seldom exceeding 3 m in length. In areas where other crocodilian species (eg Melanosuchus niger and Crocodylus intermedius) have been removed or reduced in numbers, Caiman crocodilus has established itself. Feral populations now exist in Florida (USA) and Cuba (Isle of Youth).

During the dry season, Spectacled Caimans can congregate in small pools in large numbers. At such times, large caimans may prey on small ones. At the end of the dry season they can sometimes be found buried in the mud, in smaller, shallow pools. Generally, caimans will do most feeding during the wet season. When conditions get drier they will stop. Caimans less than 1 m in length feed on a variety of aquatic invertebrate prey, including crustaceans and insects. Adults also take snails and crustaceans, but larger prey such as deer and pigs may also be taken. Observations show that caimans play an important role in recycling the water ecosystem.

Caiman crocodilus reach maturity at about 4 years of age in some areas, and females lay an average of 30 eggs in a mound nest. The females will remain near their nests throughout incubation, but their role in preventing predation on the eggs is unclear - predation rates in some areas exceed 80%. Tegu lizards are a significant predator on the eggs.

Hatchings typically occur in November, and females remain with their hatchlings for at least the first few weeks of life. Sometimes one adult will even look after hatchlings not belonging to her clutch. However, if water levels recede greatly, females either abandon their young or set out and take the hatchlings along in order to find deeper water to ensure survival.

For 2001-2005, international trade involved an average of 612,000 C. c. fuscus and 45,000 C. c. crocodilus skins per year, mainly derived from captive breeding in Colombia. In an undisturbed environment, thus when hunting pressure is reduced, C. crocodilus populations may recover quickly.

 

Yacare Caiman (Caiman yacare)

The Yacare Caiman occurs in Southern Brazil, Southern Bolivia, Paraguay and Northern Argentina. The species is morphologically and ecologically similar to the Spectacled Caiman (C. crocodilus), with males reaching up to 3m in length and females 2.5 m. Actually, it was once considered to be a subspecies of C. crocodilus but due to different morphological characteristics (such as coloration, skull morphology, etc.) and its distinct range it was elevated to species rank.

Caiman yacare is found in a wide variety of habitats including lagoons, swamps, ponds and slow moving and meandering rivers. The diet mainly consists of snails, crustaceans, insects and fish, but also birds, reptiles and mammals. For feeding on fish C. yacare, like other caimans, may use a tactic called collective fishing: 2-15 animals will line up in a channel against the current and grab passing fish without individual aggression.

Females will place their mound nests in the forest close to canals and rivers and, lay 21-38 eggs. This usually occurs in the middle of the wet season (December-January). Females will more or less guard the nests and, when juveniles hatch they will be defended aggressively.

Caiman yacare is subject to ranching in Argentina and wild harvest in Brazil, Paraguay and Bolivia.