American Crocodile

Habitat
These crocodiles establish territories in large rivers or streams, swamps, lagoons, or estuaries. They can tolerate salt water, so they may also be found in salt marshes, freshwater marshes, mangroves, swamp forests, river mouths, and sometimes in the open ocean. The bodies of water in which they live are usually in lowland dry, moist, or wet forests.

Range
This species ranges from Mexico to Peru on the Pacific slope and to Colombia and northern Venezuela on the Atlantic side. Southern Florida and some Caribbean islands are also home to the American Crocodile. In Costa Rica it lives in the lowlands along both coasts but is mostly restricted to national parks.

National Parks
Corcovado National Park, Santa Rosa National Park, Carara National Park, Tortuguero, Cañas, Taboga, and on the Tarcoles river near the Pacific coast.

Physical Description
The only other crocodilian in Costa Rica is the Spectacled Caiman; the crocodile is considerably larger and has several other distinguishing features. The American Crocodile’s head is more narrow and elongate with a skinnier snout, and the fourth tooth on both sides of the lower jaw is visible when its long mouth is closed. The croc also lacks the bony ridge that the caiman has in front of its eyes. This croc is different from other crocodiles in the Americas because the adult has a smooth bump or wart in front of each eye. Its body can be shaded from green to olive or grey with dark crossbands on its back and tail and a white or cream belly. It has webbed fingers to aid in swimming.

Biology and Natural History

At one time, the American Crocodile lived in most lowland areas of Central America. This powerful animal was excessively hunted for its valuable skin and because they were believed to pose a threat. By the 1960s, they were exterminated from much of their former range. A concentrated effort in the 1980s and 1990s helped this crocodile return to more of its former home ranges, and now it lives in protected areas along both coasts in Costa Rica.

The croc is more active at night, and during the day it may bask for hours on the shore or bank, saving energy. When it gets too hot, it will open its mouth or cool off in the water, where it spends the majority of its time. Sometimes they search underwater caves for refuge. Large individuals of this species can stay submerged without air for over an hour—they are skilled and swift swimmers.

Adults are very territorial and use vocalizations or physical warnings to protect their boundaries. This croc is a comparatively vocal species, especially during the breeding season when it may make low grunts or loud roars. Adults copulate in water, after which the female lays and covers 20 to 60 eggs in a nest dug out of the ground. She guards the nest for up to 3 months. The sex of a crocodile is affected by egg temperature during incubation, which is referred to as temperature-dependent sex determination. When the hatchlings begin to emerge, they scream for her. She carefully helps them exit and carries each baby in her mouth to the water. She will stay with them temporarily to protect them from predators, namely small mammals and birds, which may also eat crocodile eggs.

Adult American Crocodiles do not have any predators, with the exception of large sharks, humans, and sometimes a large jaguar. This species is capable of reaching lengths that make it one of the largest crocs in the world. However, large individuals have been intentionally targeted, so crocodiles longer than 4 m are rare. Although the crocodile has a menacing reputation and certainly should not be provoked, individuals large enough to kill humans have become very scarce. The crocodile is still endangered. Poaching is still an issue, and many populations are affected or threatened by habitat destruction in the Tropics.

Diet
Young crocs mostly eat aquatic insects, crabs, small fishes, and amphibians; larger individuals will eat any aquatic animals that they find, from crustaceans, snails, fishes, and frogs, to turtles, iguanas, caimans, water birds, and small mammals.

Height/Weight
Crocodiles are just 250 to 300 mm when they hatch, but over their lifespan they can become massive. Most adults average a length of 2.5 to 3 m and weigh 100 to 270 kg. The largest males can reach 6 or 7 m, making this one of the largest species of crocodile in the world, but few individuals of either sex reach more than 4 m in length.

Taxonomy
Order: Crocodilia
Family: Crocodylidae

Sources
Savage, Jay M. The Amphibians and Reptiles of Costa Rica: A Herpetofauna between two Continents, between Two Seas. The University of Chicago Press, Chicago, 2002.
Leenders, Twan. A Guide to Amphibians and Reptiles of Costa Rica. Zona Tropical, S.A, Miami, FL, 2001.
Scott, N. J., J. M. Savage, and D. C. Robinson in: Janzen, Daniel H. Costa Rican Natural History. Chicago: University of Chicago Press, 1983.

-Amy Strieter, Wildlife Writer