status: Endangered, Southeast Asia, Pacific Islands; Threatened, Australia, ESA
Description and biology
The saltwater crocodile, also known as the estuarine crocodile or Indopacific crocodile, is one of the largest living crocodiles on Earth. It measures between 10 and 23 feet (3 and 7 meters) in length and weighs over 2,000 pounds (908 kilograms). It has a large head, a long snout, and webbed hind feet. The upper part of a mature saltwater crocodile's body is dark green to black in color. Its belly is yellow or cream. This crocodile's diet includes fish, snakes, birds, turtles, cattle, horses, and even humans. The saltwater crocodile sometimes drags its prey under the water to eat later.
Male saltwater crocodiles reach sexual maturity around 16 years of age; females reach sexual maturity at 10 years. The breeding season varies with geographic location, but most often occurs during an area's wet season. After building a mound nest out of leaves, grass, reeds, mud, and other plant debris, a female lays 40 to 60 eggs inside the mound. As the plant matter
making up the nest begins to decompose, the temperature inside the nest rises and the eggs begin to incubate (develop). After 80 to 90 days, the eggs hatch. Sharks and other aquatic predators often prey on the young saltwater crocodiles.
Habitat and current distribution
The saltwater crocodile is the most widespread crocodile species. It is found in Southeast Asia, Indonesia, the Philippines, New Guinea, and northern Australia. It is at risk throughout most of its range, except in Australia (where it is at low risk of extinction). Biologists (people who study living organisms) estimate that tens of thousands of saltwater crocodiles currently exist.
The saltwater crocodile prefers to inhabit coastal brackish waters and the tidal sections of rivers—areas where freshwater and salt water mix. However, it has also been found in freshwater rivers and inland swamps and marshes.
History and conservation measures
Like many other crocodile species, the saltwater crocodile has diminished in number mainly because of hunting for its hide. The loss of its habitat has also contributed to its decline.
Hunters like the hide of this crocodile because it produces a large quantity of valued leather. During the 1950s and 1960s, hundreds of thousands of saltwater crocodiles were killed every year to satisfy the demand for crocodile leather. International treaties now regulate the trade of this species. Since the crocodile's range extends over such a large area, however, illegal hunting and trade are difficult to control.
Habitat loss further threatens the remaining saltwater crocodiles. Coastal mangrove habitats, in particular, have been steadily cleared and drained to create farmland throughout the crocodile's range.
In Papua New Guinea, a controversial program has been established whereby newly hatched saltwater crocodiles are taken from the wild and reared in captivity. After three years, they are killed for their hides. Supporters of this program say many of these young crocodiles would have been killed by predators in the wild. Using their hides satisfies the commercial demand for leather without damaging the species in the wild. Opponents believe the program hurts the saltwater crocodile population because many of the young crocodiles are not even given the chance to survive in the wild.
In the Bhitarkanika National Park in India, a captive-breeding program has been quite successful. A number of the saltwater crocodiles that were raised in captivity and then released into the wild have begun to breed.