Monday, May 17, 2010
"Shaving the Rhino"
Sunday, April 25, 2010
Rhino: Extinction Countdown
High demand from
To learn more about rhino…read on
White rhino are the second largest land mammals on earth and as such enjoy a position amongst the ‘Big 5’ – historically those animals most dangerous to hunt but now the most sought after by tourists.
The shape of the lips led to the naming of this rhinoceros as Dutch settlers referred to the ‘wyd’ mouth (meaning wide) and colonialists misinterpreted this to mean white. The wide muzzle (20cm) comprises a more sensitive upper lip (which is used to manoeuvre grass clumps into the mouth) and a hard lower lip (against which the top lip presses to severe the grass). Both lips are swiped upwards to effect the neat cropping of grass. No incisors are involved at all in ingesting grass but broad, intricately enamelled molars inside the cheeks provide a grinding surface for mastication. A rhino crops the grass continuously moving its head in a semi-circle and then stepping forward to repeat the action. White rhinos maintain their own neatly cropped pastures in stands of favoured grass species (like Themeda triandra, Panicum maximum and Urochloa mossambicensis) which are often well concealed amongst taller grass. They rotate the use of their favourite feeding areas so as not to obliterate them. Rhinos practice geophagia (chewing of soil) to supplement minerals deficient in their all grass diet.
Because of the large quantity of fibrous grass that a rhino must consume to satisfy its energy requirements, it requires daily (if not twice daily) access to drinking water to assist with digestion. Rhino usually make their way to water late in the afternoon or even after dark. Because of their reliance on water, bulls that do not have a water source within their own territory will have to leave their turf and enter other bulls’ territories in order to drink. So long as an intruding rhino behaves submissively, territorial bulls will tolerate water-related visits from neighbours. A bull rhino shows its submission by urinating in a stream (on his own territory he would spray). He may also flatten his ears and squeal to reassure the territory owner of his innocuous intentions. If water is scarce, rhino can only go for up to four days without drinking.
White rhino are fond of wallowing in mud in order to help them cope with excessive summer heat conditions. A good caking of mud prevents sunburn and keeps a layer of moisture close to the skin to assist with keeping cool. The mud once dried also acts as a parasite-removing wax treatment that the rhino will rub free of their skin against trees, rocks or termite mounds. Rhinos are prone to reusing their rubbing posts that eventually become quite smooth and polished. They may also use these posts to scratch in hard to reach areas such as the inner legs and belly. While they wallow in the mud, terrapins will also pluck parasites off the rhino’s hide.
They have massive necks with a large nuchal hump over the shoulders. The thick albeit short neck supports the large head which is held low to the ground in order for the rhino to feed on the lowest-lying form of vegetation, grass. Having its head close to the ground also facilitates the use of its nostrils to detect olfactory (scent-related) clues regarding territory and the location of other rhino. Rhino rely on their sense of smell since eyesight is limited. The powerful neck also provides the force behind the defensive horns.
The most prominent feature of the rhino is its horns. These are weapons of defence used to protect itself and its offspring from predators or during bouts of combat. Horns are made of keratin (the same substance as fingernails) and grow 2-6 cm in a year and continue to grow throughout life. They are often worn down through usage and tend to be longer and thinner in cows which do not engage them as frequently as the bulls. The record horn length for a white rhino is 1.58m.
Rhino are active throughout both the day and night and spend at least half their time feeding in order to satisfy the nutritional demands of their huge bodies. They prefer to rest during the heat of the day which they will do under the cover of dense bush. They also take refuge in thickets should the weather turn particularly cold or windy. When they sleep they do so relatively soundly breathing heavily. During sleep the ears may be seen instinctively flicking in all directions and rhino can react to disturbing sounds with impressive speed if the need arises.
White rhino females are fairly gregarious (live with others of their own kind) and it is quite unusual to find a cow alone. A female is most often accompanied by her latest calf but sometimes the previous calf (who would have been chased off when the newest one arrived) will also accompany her. Cows without calves will often pair up and newly independent adults may form groups of the same (or even mixed) sexes of up to five individuals. Where there is good grazing or localized water, white rhino cows and their young may form aggregations sometimes numbering ten or more. Most of the time, female rhinos live in undefended home ranges that overlap with one another. Sometimes these home ranges can coincide with the territories of up to seven different bulls. Where there is abundant food and water, these ranges may be as small as 6km2 but may expand to 20km2 during dry and difficult seasons.
White rhino bulls are fiercely territorial and are always found alone unless courting a female. Although they mature at around four years old, bulls are not usually able to contend with other bulls for territories until they are twelve years old. So long as they demonstrate submissiveness to the older and larger territory holders, younger bulls are tolerated.
A bull rhino defends an area between 0.75 and 14km2 depending on the availability of resources. His territorial boundaries typically follow natural barriers like water courses, topographical ridges and even man-made roads.
To demarcate his territory a bull rhino employs a number of visual and olfactory signals. Patrols along well used paths take place to establish and reinforce boundaries. While patrolling, the bull will urine-spray backwards onto bushes and other conspicuous objects. Every 30m or so, the bull will also create visual scrape-markings with his feet that simultaneously become impregnated with his urine. As he continues his patrol, the scent is laid in the form of an olfactory (smell) trail wherever his feet touch. This is also achieved by kicking his dung with his hind feet after defecating. Intermittently along the territory boundaries, large accumulations of dung (known as middens) are formed and constantly added to by the bull and even by his neighbour. Cows (and subordinate bulls) will deposit their dung on a bull’s midden as and when they pass but refrain from breaking up their dung in the manner of the territorial bull. These sites provide important information to the territory owners such as when and who has passed through his turf.
When territorial bulls encounter one another along their boundaries, their responses are ritualized and posturing displays will satisfy one another of their independent statuses. However, when there is a new territory to claim or an oestrus cow in question, bulls will fight. Their primary weapons are their horns with which they will spar and attempt to hook one another. The skin over a rhino’s shoulders is 25mm thick to help reinforce this area against blows from opponents’ horns. Fights can be fatal.
Rhinos have relatively poor eyesight and can only really see well at close range. They do however respond to movement at greater distances. To compensate, the senses of hearing and smell are very well developed and both are employed for the purposes of communication and detecting danger. A rhino’s ears are constantly moving rotating independently in all directions to collect auditory clues. When a sound is detected, both ears focus in that direction. The ears are conveniently placed a top the long head to collect sounds while the low slung muzzle is optimally placed to smell.
The collective known for a group of rhino is appropriately ‘a crash of rhino’. Although they seem quite ungainly, rhino are able to charge at a speed of 40kmph if they need to. Rhinos that are stresses will perform displacement behaviour. This may take the form of curling up the tail, a nervous bouncy gait around the same spot, turning side on to the disturbance or rubbing the horn on the ground. Cows with young are especially protective. When a cow and her offspring flee from danger, the calf always runs ahead.
White rhinos differ from black rhinos in several ways. Black rhino are smaller than white rhino overall. They have shorter heads that are carried higher up on their shoulders than the white rhino to accommodate their browsing (not grazing) habits. The black rhino has a prehensile hook-shaped lip to help it secure leaves and twigs (compared to the wide mouth that the white rhino uses to graze). Twigs are cropped at a 45 degree angle due to the shape of the black rhino’s teeth and this angle is clearly identifiable in the twigs in their droppings. The ears of the black rhino are smaller and rounder and it lacks the large nuchal hump of the white rhino over the shoulders. The black rhino is one of
Thursday, April 1, 2010
50|50 is back! SA's longest running environ show...
Lion’s Rock Sanctuary
Lion’s Rock is a sanctuary for lion rescued from atrocious conditions in zoos around the world. In the last season of 5050 we saw several Romanian lions brought to Lion’s Rock in an emotionally charged story. Wendy Willson now follows up on the rehabilitation of one particular lion “Caesar” and we have a look at how Lion’s Rock provides a second chance to these abused animals. Recently more lion were brought into the relative freedom of Lion’s Rock Sanctuary. The latest arrivals are rescued from various zoos in
Verlorenvlei (http://www.verlorenvlei.co.za/)
The main story is about another pristine wetlands area that has come under threat to mining. Verlorenvlei is one of the largest natural wetlands on the West Coast. It offers important bird habitat, houses unique biodiversity and is a RAMSAR site of international conservation importance. One of the rivers that feed into it, the
The Geneva Motor Show is the biggest car expo in the world and this year many of the exhibitors had their latest green technology on show. Simon Gear visits the show and test drives the electric and hydro-fuel cell cars. 5050 explore the variety of technologies involved in greening the motor industry and closer to home, examine South Africa’s very own Joule that starts and accelerates on electricity. But how sustainable is this type of vehicle where one would need to plug into the national grid to charge it, a supply that is coal-generated and carbon heavy on the environment.
Crocs of the
An ongoing saga where the crocodiles and barbel fish of the once pristine
Monday, February 22, 2010
Feb Birding: Finding feathers in a furnace!
February has proven a productive birding month and in just a few days we clocked up 130 species on the basic birding course at Karongwe Game Reserve with the year-long Ecotraining students (http://www.ecotraining.co.za/). This is remarkable simply because the weather was exceptionally hot with one particularly eager thermometer clocking a 480C at one point. We resorted to very early starts and much birding from the vehicle so that in between bouts of viewing we could engage the ‘manual air-conditioning solution’ that an open Land Rover provides!
Being in a vehicle also enables you to cover more habitats which house different species. The most obvious feathered feature wherever we went was the Woodlands Kingfisher. These are conspicuous birds thanks to their bright colours and noisy, active habits. The “chip-crrrrrrrrr” is unmistakeable and unrelenting but when one considers that the
Most species of kingfisher are strictly monogamous (one male and one female pair up). The males defend territories and establish a pair bond with the female through visual displays and courtship feeding. The
The bright blue of the Woodlands kingfisher’s feathers is the result of an effect called tyndal scattering. This is where the layers of structural keratin that make up the feathers are interspersed with air spaces and reflect particular wavelengths of light to appear blue. There is no colour pigment in the feathers.
Without any colour yet just as conspicuous for its vocal habits as the Woodlands, is the fork-tailed drongo. It’s a resident species but to impress females and ward of rivals it has developed a unique technique. In a process known as mimicry, the fork-tailed drongo copies phrases of songs and sounds belonging to other species of bird much like robin-chats. The complexity of the assembled tune is suspected to be an indication of fitness to females. Males that are able to remember and knit together long sequences of phrases are considered better partners. A strong mimicked vocal signal also will intimidate rivals and convince them of the singer’s superiority.
Birds sing to advertise their territories and to attract mates and subsequently build bonds with those mates (especially if they are monogamous and only have one). Birds sing most earnestly in the morning when the air is clear and still and sound travels furthest and loudest. This is known as the ‘dawn chorus’. They also utilize the dawn chorus to remind their neighbours that in spite of a night of darkness since last they called, they are still very much in attendance of their turf. Birds call in the late afternoon again to establish ownership of an area before they sleep.
Good rain has meant that Karongwe is green, lush and somewhat overgrown. Spotting birds along the shorelines at the waterholes was difficult but the characteristic 3-syllabled whistle of the white-faced ducks betrayed their presence in the area as they were flying over in the evenings to forage. These ducks are fairly unique among ducks for their tendency to both whistle instead of quacking and also to feed at night on grass, seeds, grain and even fruit (like geese). Ducks have flat bills which are used for sieving edible particles out of the water. Many ducks up-end or dabble, partially submerging their upper bodies in order to access food below the water. The food they usually consume includes various parts of aquatic plants, insects, detritus in mud, algae, crustaceans and other invertebrates. White-faced ducks dabble for food but may also dive fully under the water to obtain something they desire.
Despite the fiery weather conditions, the birding week was productive and satisfying and I look forward to the next one when I can listen to the fiery-necked nightjar under cooler night skies!
Tuesday, January 19, 2010
Earthworks - The Incredible Dung Beetle
There are about 7000 species of dung beetle
described world wide of which southern
Dung beetles are astute navigators and can detect fresh dung within seconds, having it fully colonized within minutes and completely removed within a day. Dung beetles can bury more than 1 metric ton of dung per hectare per year. In this regard they are exceptionally important ecologically being responsible for the removal of wastes to under the ground and consequently they destroy the eggs of internal parasites and reduce populations of pest species like flies. They simultaneously return nutrients to the soil and inadvertently facilitate the germination of seeds caught up in the dung they bury.
Ball-rolling dung beetles generally roll balls 50 times heavier than themselves, occasionally up to 80 times. Dung beetles may have preferences for different types of dung. Some species specifically colonise course elephant and rhino dung while others may utilize buffalo, zebra or smaller animals’ dung. Seventy two percent of all dung beetle species prefer herbivore or omnivore dung to carnivore scat.
There are four different groups of dung beetles according to what they do with the dung they collect.
The endocoprids or ‘dwellers’ remain inside the pile of dung, living and breeding in situ.
The paracoprids or ‘tunnellers’ bury dung directly underneath the pile of dung as their larval food supplies.
The telecoprids or ‘rollers’ are the species that roll balls and take the dung away from the original site to be eaten or buried elsewhere effectively reducing competition with the endo- and tele-coprids. The ball is pushed with the beetle’s hindlegs while standing on the forelegs.
The cleptocoprids steal balls from the telecoprids in which to lay their own eggs.
The most conspicuous dung beetles are the telecoprids (ball rollers). They typically roll balls of dung for different purposes.
A pair may roll a ball of dung together to eat. This is called a food ball. The male may roll a ‘nuptial ball’ for a female into a hole in which they will mate and then consume the ball together. The ‘brood ball’ is rolled as a larder for the dung beetle’s larvae. The male will roll the brood ball upon which the female will sit to lay a single egg. This she pats down into the ball with dung giving the finished ball a pear-shaped appearance. The ball is buried and the outer shell hardens to keep the insides moist. The larva, on hatching, will begin to feed on the reserves and thereafter pupates in its underground dung-walled chamber. Up to 60 eggs can be laid per female per season meaning that the male must roll 60 of these brood balls alone.
Adult dung beetles can live for two years or more but they are preyed on by a host of predators including baboons, honey badgers, civets, hornbills, owls and rollers. Robber flies and wasps may catch the smaller species. The larvae of the beetles are primarily dug out of the ground and consumed by honey badgers but civets and mongoose may also do this.
Some dung beetles are flightless due to fused elytra (wing coverings). These populations are extremely endangered as they can’t disperse easily. A particularly healthy population inhabits the
Dung beetles are superbly adapted for their lifestyles. They are large and robust often with a lovely metallic sheen. They have stout front legs which are serrated and able cut through compacted dung. The front tibiae are broad and toothed and together with the flattened head are used for digging and raking together dung and patting it into a ball. The antennae are fanned and club-shaped and probably related to detecting and navigating to dung piles.
Tuesday, December 15, 2009
Meeting Mrs Ples
I had another unique adventure with Mark Tennant the other day (www.animalsartsandancestors.com). I went to meet the original Mrs Ples. Her remarkably intact skull now resides in a velvet cased box inside the Transvaal Museum. What a wonderful visit if a rather large step back in time!
But let’s go back a sec…who’s Mrs Ples and what’s the big deal?
At the helm of early evolutionary studies in South Africa were the likes of passionate palaeoanthropologists such as Professor Raymond Dart and Dr Robert Broom. Dart’s contentious publications were the first to propose that there was in fact a hereditary link between the ape and human. This supposition was strongly supported by Broom’s discovery of a new hominin fossil in the Sterkfontein Caves in the form of Mrs Ples - the media shortening for Plesianthropus africanus (later changed to Austrolopithecus africanus). The discovery of Mrs Ples ultimately opened the world up to the realisation that not all early hominids are direct ancestors of modern man. These men’s work was foundational in the world recognising that Gauteng’s Cradle of Humankind was paramount in the understanding of human ancestry having produced thousands of hominin fragments, hundreds of thousands of animal fossil fragments and ten thousand stone tools that cover 3 major stone-cultures. Sterkfontein is the longest ongoing excavation in the world having been dug continuously for three decades and intermittently for the previous three.
Mark took me to The Cradle a while back and it blew my mind.
The part of Gauteng that has come to be known as the Cradle of Humankind is a world-renowned heritage site due to the fact that 35% of the world’s hominin fossils have been discovered here in 12 individual sites and is characterised by 2.8 billion year old rocks. The granite, some of the most ancient rock on the planet, protects an expansive network of underground caverns amongst softer dolomite and these preserve the clues of a 3.5 million year old story.
The Cradle’s undulating grasslands with their moist valleys and wooded slopes have been ideal for hominin habitation for millennia (the period when most human evolution occurred is called the plio-pleistocene) in spite of interruptions such as climate variations and the presence of inland seas. It seems the original human-like apes at 1.3m tall first roamed here about 3 million years ago. They lived in small social groups and dodged sabre-toothed cats and prehistoric hunting hyenas. Australopithecus africanus is thought to have been the original ancestor of the Homo genus which appeared when a series of hot and cold cycles created a window for speciation about 2 million years ago.
Human evolution is complicated because it branches and is not as linear as originally thought. It seems some of the original Australopithecus africana gene line took on the traits of a more robust ape-man with a flatter face and larger teeth while another evolved into Homo habilis which had a larger brain and more carnivorous diet (and thus different lifestyle skills in terms of hunting rather than gathering) than the Australopithecines.
The clues tell us that by 1.5 million years ago Homo erectus was beginning to displace H.habilis probably due to his new found ability to tame fire for warmth and protection, flames being transported from natural sources like lightning-induced veld fires. Fireplaces in the Forum Homini rooms remind guests of this critical turning point in our evolution. Remarkably, this same tool harnessed for simple tasks such as cooking food, would eventually take mankind to the moon! From this point, humans developed quickly.
The Homo genus had a mental capacity and social organization much more advanced than his predecessors and it appears dispersed northwards to colonise Asia and then Europe. Those that remained in southern Africa developed into archaic Homo sapiens 800-200 thousand years ago. These individuals excelled in communication and language began to develop as well as expression through art and the crafting of jewellery, weapons and more advanced tools. Many controversies exist around the evolution of man and scientists have limited (not to mention petrified) evidence to work with to prove or disprove their theories.
Standing in the cool, dark space under the earth is quite unnerving. Not because its particularly claustrophobic but rather because standing there is like being inside a sacred grave site. Some of the earliest forms of life, prehistoric blue-green algae’s (known as stromatolites) have been found here. Nature’s embellished, arching ceiling and the tranquil underground lake are tomb-adornments fit for kings. The most intact australopithecine ever found is still being meticulously extracted from the rock in this cave. ‘Little Foot’s’ foot bones were found in a bag containing discarded lime-mining debris blasted some 65 years previously and painstakingly matched to the rest of the skeleton where it had come to rest, his skull resting on an outstretched arm, after falling down a vertical shaft 4 million years previously.