Nile Crocodile

The population and range of the once widespread Nile crocodile is now seriously reduced, by both the demand for skins and the destruction of natural habitats.

Nile crocodiles were once widespread in eastern and southern Africa, but are now scarcer. With powerful jaws, strong tails, a terrifying turn of speed and stealth belying their enormous size, these crocodiles are efficient killing machines. Nile crocodiles have evolved to be very good at fishing, and during the times of the year when fish migrate along the rivers they hunt cooperatively. Forming cordons across rivers, they herd the fish into shallow waters, where they can be picked off with ease.

The Nile crocodile's powerful body is covered in greyish plate-like scales. The powerful tail is ridged with two keels of scales.

These large and very dangerous crocodiles account for possibly several thousand human deaths every year, lurking at the water's edge while remaining out of sight.

Nile crocodiles are highly efficient predators, often working collectively, as demonstrated by the so-called "death roll", when one crocodile seizes and holds an animal, while others dismember it by gripping its limbs and spinning around their bodies. They favour rivers, but also occur in brackish water. It is very hard to spot a crocodile in the water, as these reptiles lie concealed, with just the very top of the head, including their eyes, above the waterline.

They help to keep the environment in balance by eating catfish. By keeping the catfish numbers in check, Nile crocodiles allow the smaller fish, which are eaten by catfish, to thrive, providing food for more than 30 species of bird. In turn, bird droppings fertilize the waters, keeping them rich enough to support a large diversity of life.

The Nile crocodile preys on large mammals and birds which come to the water’s edge to drink. After seizing its catch, the crocodile drowns it by holding it under water, and then twists off chunks of flesh by spinning its own body in the water while holding on to the prey. Adult crocodiles swallow stones, which remain in the stomach and act as stabilizing ballast when the crocodiles are in water.

The Nile crocodile spends its nights in water and comes out on to the river banks just before sunrise in order to bask in the sun during the day. It leads a rather leisurely existence and does not need to feed every day.

The male defends a territory and enacts a courtship display at breeding time. The mated female lays 25 to 75 eggs in a pit near the water. She covers her eggs well and guards them during the 3-month incubation period. When ready to hatch, the young are sensitive to the footfalls of their mother overhead. They call to her from the nest; she uncovers them and carries them inside her mouth to a safe nursery area, where she cares for them assiduously for another 3 to 6 months. The young feed on insects, then progress to crabs, birds and fish before adopting the adult diet.

Distribution: Occurs throughout sub-Saharan Africa, extending to Egypt in the east, and also present in western Madagascar. Absent from the southwest of the continent.

Habitat: Large rivers, lakes, marshes.

Weight: 680 - 1000 kg (1500 - 2205 lb); males are heavier.

Length: 3.3 - 5.5 m (10.8 - 18 ft).

Maturity: About 10 years, at 3 m (9.8 ft) long.

Number of Eggs: 25 - 80 per clutch.

Incubation Period: Around 90 days; females watch over their newly hatched young, carrying them to water.

Food: Feeds on fish, but mature adults kill larger mammalian prey; youngsters hunt amphibians and larger invertebrates.

Lifespan: 70 - 90 years.

Status: Common.