Of late I have being punting the point of how wonderful the Nhlaralumi River is functioning with fewer upstream impoundments. The natural processes that follow are remarkable in such a short space of time since the failing of certain dams in January 2012.
Observing the changes in fauna and flora along the watercourse is note worthy, such as increased ranging by water dependant species buffalo and elephant as well as water birds such as jacanas, stalks and sandpipers. On any day you can find evidence of hippo everywhere, as many as nine individuals inhabiting Ingwelala, to the best of my knowledge a first for us, considering the previously water deprived river system.
Another tangible example in the lime light this month is a nesting female crocodile at Old Farmhouse. This exhibits suitable habitat for a prehistoric creature that was surely prolific in our area once upon a time.
The Nile crocodile (Crocodylus niloticus) is indigenous to Africa, and second in size to the saltwater crocodile. It is called Krokodil in Afrikaans and Ngwenya in several African languages. It has the English nickname of flat dog. Crocodiles occur Sub-Saharan, preferring warmer areas because they are cold blooded, relying on permanent water bodies of rivers, lakes, marshes and even salt water estuaries. Adult crocodiles eventually attain an average length of about four metres and a body mass of 400 kgs. The largest specimens found have measured six metres and weigh double the average!
Reproduction commences with sexual maturity around 10 years of age. Courtship involves the males attracting the females’ attention by a type of roaring sound, blowing water through nostrils and nose slapping on the water. Male competition is high, the largest individuals having success. Paired couples will fiercely guard their nest where the eggs are buried in sand on dry land, though the female is preoccupied with being the main nest protector. Egg clutches average 50 and incubation can be anything from two to three months. Monitor lizards are partial to crocodile eggs and will attempt to predate the nest if given half the chance. Nest temperature affects the dominant sex, the female gender having a broader temperature range than the males.
When ready to hatch, the hatchlings emit a characteristic vocalized squeak that alerts the female to uncover the nest. Hatchlings are then guided to the water, sometimes carried by the mother in her mouth. The hatchlings are dependent on maternal protection during the first two years whilst they grow to an average length of approximately 1.2 metres.
# 197 offered the following account of the nesting female at Farmhouse:
"The process of moving from the water to the nest site was quite interesting. She would generally move about 10m out of the water and lie for about a half hour or so, and then move another ten meters towards the nest site, and lie before moving into the bushes. On our last night there was a fascinating interaction when she was lying en route. A hyena crept up to her to investigate whether she was alive. When the hyena was about a meter and a half from the croc’s side the hyena suddenly jumped back in alarm. There was no visible movement from the croc. The hyena then circled the croc and approached directly from the front and got really close. In fact we thought that the croc might lunge forward but it lay absolutely motionless. The hyena then again suddenly jumped back in alarm and this time decided that the croc wasn’t a very good idea and left!"
Crocodiles are top predators, ferocious carnivores that enjoy a diet of mainly fish and any unsuspecting antelope that visits the shoreline. Interactions between crocodile and man are well documented, where man- eating crocodiles are either hunted or captured for translocation. Domestic livestock and dogs are also easy prey targets. Crocodile farms, both for breeding (conservation) and commercial purposes do exist and are well worth a visit, especially during feeding times. The skins and meat have high commercial value. Crocodiles are susceptible to water pollution.
A dozen other interesting facts about a crocodile:
- Jaws are very powerful for a biting action, in relaxation mode the jaw is extended in an open gape.
- Large prey is often shared when feeding involves rolling and twisting to break off chunks of flesh. On land crocodiles and other large carnivores may steal kills from each other during lean times.
- Crocodiles are masters of disguise and deploy ambush tactics when hunting.
- Females lay their eggs approximately 60 days after mating.
- Females may nest in close proximity to each other and form crèches to protect the young.
- Hatchlings have a specially adapted and disposable “egg tooth” used for breaking through the egg shell.
- Hatchlings hunt for themselves.
- The conical shaped teeth are specially adapted to aid grip when catching large prey.
- A nictitating membrane aids eye protection.
- It can hold its breath for a couple of hours.
- Estimated life span may be as long as 100 years.
She lays 25 to 80 eggs in the nest, then settles in for a long vigil
Hatchlings have a specially adapted and disposable “egg tooth” used for breaking through the egg shell.
Weirs and Dams can restrict natural migration of aquatic life
Facts researched on the Internet; text by John Llewellyn.