Boat Cruise
Boat Cruise
Lioness Yawning at Vumbura Plains Camp
Lioness Yawning at Vumbura Plains Camp
Old Palapye Museum
Old Palapye Museum

Crocodile

Crocodile
Setswana Name: 
Kwena
Scientific Name: 
Crocodylus niloticus

Size: 250 - 350 cm; max. 590 cm

Description

The Nile Crocodile can measure in weights exceeding 1000kg. It has long jaws and sharp, noticeable teeth and webbed hind feet. Its skin is covered in geometrically arranged, horny plates; those found on top of its head are fused to the skull.

The Nile crocodile’s tail makes up 40% of its total body length and has two raised dorsal keels.  The Young adult’s crocodiles are green, with irregular black markings over the back and sides; its throat and belly are straw-yellow.  The adults are darker, being more olive to grey in colour with a yellow or cream belly.

Habitat

These large reptiles reside in rivers, lakes and swamps; they can also be spotted in estuaries, and mangrove swamps.  In Botswana, Crocodiles are most common in the Okavango Delta and Chobe River.

Behaviour

Young crocodiles dig a burrow of up to 3 metres long in which they use for shelter for the first 3-4 years of their lives. They spend a significant amount of time outside of water and eat small prey. The sub-adults take up residence in swamps and backwaters, eating fish, terrapins, birds and small mammals.

The adults overcomes its prey with a fast, sideways swipe of the head. The tail may be used to knock over vegetation to dislodge residing birds in nests or to re-direct fish to its jaws.

Although crocodiles eat fish, particularly catfish, they will ambush and fest on game meat; antelope is a common catch, but zebra and buffalo can also feature on its  menu.  Crocodile will also attack a human being, and either injure them severely, or devour them.

Crocodiles eat large food items by biting it to smaller pieces (if it is too big). They participate in what is known as cooperative behaviour where the reptiles will cooperate in feeding on and breaking up prey to sizeable amounts.

On hot days, they enjoy basking in the hot sunlight on sand bars and river banks; to keep cool in these hot temperatures, they lie with their mouths open loosing excess heat through evaporation. Swimming is an effortless affair for crocodiles who use their tail and webbed feet to allow careful maneuvering during mating and when preparing to ambush prey. To help them breathe under water, its valved nostrils and gular close at the back of the mouth enabling them to feed underwater. These amazing reptiles can live up t0 60 years, some even up to 100years.

Reproduction

Crocodiles take very good and close attention to their young. It reaches sexual maturity in 12-15 years when it is about 2-3 metres long.  (70-100kg).

During the mating season, males develop a dominance hierarchy; mating takes place in water in July-August. The female will select a suitable sunny sand bank above flood water level and which has good drainage and cover nearby. Unless this chosen and rearing land is disturbed, the female will use it for the rest of her life.

In November, commonly at night, it will dig a hole (30-45cm deep), and lay 16-80 hard, white shelled eggs.

The nest is heavily protected against predators and other crocodiles; the female will even refrain from eating during this time but may go into water to drink. The female will even keep males at bay during this time. Once the hatchlings hatch 84-90 days later, they can be heard by their high pitched, chirping sound that can be heard up to 20m away. The female will carefully open its mouth and carry the young into her mouth to the water for them to be released. They remain close together in a group for 6-8 weeks.

Interestingly, the sex of the hatchlings is determined by the egg incubation temperature. Females are produced in temperatures of w26-30 degrees, whilst males at a higher temperature of 31-34 degrees.