One of Africa’s most dangerous animals, the Nile Crocodile is also by far the largest and one of the most widespread reptiles found on the continent. Adults measure on average around 3.5m long , but the largest accurately recorded specimen (from Tanzania) had a length of 6.45m and weighed 1090kg!
Nile Crocodiles inhabit rivers, marshes, lakes, lagoons and estuaries, and even venture out to sea at times. From hatching crocodiles are entirely carnivorous, feeding at first on small fish, insects, crustaceans and frogs. Fish also make up about ¾ of the diet of adult Nile Crocodiles, though they are capable of drowning animals up to the size of an adult buffalo when the opportunity presents itself! Such a large meal can sustain the crocodile for many weeks. When a meal is too large to swallow in one gulp, Nile Crocodiles will take a large bite and then spin their bodies in the water to tear a mouthful of flesh from the carcass. We’ve also seen Nile Crocodiles using their bodies and tails to trap schools of fish against the bank and pick off their hapless prey one at a time.
Often living in close proximity to sizable human populations, it is no surprise that Nile Crocodiles are responsible for hundreds of human deaths annually, especially when people are directly reliant on waters inhabited by crocodiles for their daily needs (fetching drinking water, fishing, washing clothes, bathing, etc).
At times, Nile Crocodiles can congregate in huge numbers, especially when water resources dwindle during the dry season or at a favourite nesting area. They are surprisingly fast on land, and capable of running at up to 17km/h! By day they like to bask in the sun on a rock or sandbank with their mouths wide open when they start to overheat, preferring to stay in the water at night. They hunt mostly at dawn and dusk, approaching prey on land with only their nose and eyes breaking the surface of the water.
Adult male Nile Crocodiles are territorial, and often get involved in deadly battles with other males. In South Africa the mating season stretches through winter, with the females then moving to a favourite, suitably sunny spot high enough above the floodline, to dig their nest – a hole in the sand between 20 and 45cm deep. Here she lays up to a 100 eggs, which she then covers again with sand. She diligently guards the nest for the next three months until the eggs hatch. The hatchlings call out to their mother, who digs them out and moves them, very carefully, to the water in her mouth. She looks after them for another 2 to 6 months in a nursery area, which is usually a densely vegetated stretch of water (they feed themselves from hatching). The eggs and hatchlings are a delicacy for a wide range of predators both on land and in the water, and despite the mother’s best efforts only about 2% of eggs laid reach maturity. The temperature at which the eggs are incubated determines the sex of the babies – lower temperatures produce females. Young crocodiles spend much of their time out of the water catching insect prey. It is estimated that Nile Crocodiles can live to an age of 100 years in the wild.
The IUCN lists the Nile Crocodile as “lower risk / least concern“, and while the species is threatened by habitat loss, environmental poisoning and poaching their numbers across their distribution range are estimated at between 250,000 and 500,000. It is found from the upper reaches of the Nile in Egypt, and most of West Africa south of the Sahara, southwards through Equatorial and East Africa to Angola in the West and to South Africa’s east-flowing rivers from the Tugela nortwards. They are also found on Madagascar and farmed for their meat and leather in several countries. In South Africa wild Nile Crocodile populations are considered to be vulnerable. The country’s largest wild populations are to be seen in the iSimangaliso Wetland Park and Kruger National Park, while the Crocodile Centre on the outskirts of the town of Saint Lucia in Kwazulu-Natal is a must visit for anyone interested in this species as well as the two other African species of crocodiles (few authorities have as yet recognised the West African Crocodile (C. suchus) as a seperate species).