More than half of a wildebeest’s life is spent resting, but being social animals, they too enjoy a little get–together.
Just what exactly does a wildebeest in Etosha National Park do all day and at night? A casual observer, after watching a solitary animal or a herd of these cousins of cattle, may say: “Well, they seem to mostly, graze, rest and sometimes drink water”. Indeed a correct impression of these peculiar antelopes, which typify the wildlife scene on the open plains of Namibia’s foremost refuge for wildlife. This impression is only part of the picture however, although wildebeest do spend the greatest portion of their sometimes-brief life either lying or standing motionlessly. Nevertheless, as a ruminant they possesses a four–chambered stomach that requires a regular supply of grass. Consequently, the apparently “resting” wildebeest is often busily engaged in circulating and digesting its food by “chewing the cud”.
Naturally, it takes a certain amount of energy simply to stay alive, even if an animal is lying resting. A living body must continue its basic processes of breathing, heartbeat, digestion, and maintain its temperature. This lowest form of activity is called “resting metabolism”. It is the most economical rate at which any animal can use energy and still stay alive and healthy. Any additional activity will therefore mean an increase in this “resting metabolic rate”.
How to measure the amount of energy a free–living wildebeest needs to survive the harsh environment of Etosha? A team of academics, comprising physiologists, biologists, veterinarians and statisticians were engaged over a period of a year to obtain this elusive answer. Applying well–tested formulae that are based on measurements of the energy used by domestic cattle, we adjusted these for the wildebeest’s way of life. Initially Etosha’s wildlife veterinarian temporarily immobilized a total of 70 wildebeest. They represented a random sample of the thousands of “gnus” that inhabit Etosha, including adults and immatures of both sexes. Brightly coloured, numbered collars were fitted around each animal’s neck, making it individually identifiable. Blood and tissues were taken from these and freshly–dead wildebeest, the latter when we located kills by lions. Such samples were needed by physiologists to complete the picture we were attempting to develop about the life of a wildebeest.
My part of the investigation was to follow the marked wildebeest for entire days and nights over a period of one year. Armed with binoculars, tape recorder and stopwatch, I relied on a four–wheel drive vehicle to keep up with the wildebeest herds as they led their lives. The statisticians were merciless in their requirements! They required literally several million samples of information, deciding that the best units for collecting this would be in the form of seconds, measured by stopwatch. Thus, my replays of the tapes sounded something like “wildebeest No. 10 is walking; stop walking after 23 seconds and stand resting; stop after 7 seconds and start grazing; stop after 35 seconds and start walking…”. This often-monotonous commentary continued for a period of 15 minutes, or 900 seconds, which was the longest that I could accurately monitor a marked animal without making significant mistakes on the stopwatch. I needed a further 15 minutes to rest and position my vehicle for the next 900–second recording session. It was imperative that the animal I was following was not influenced by my presence, as this would have resulted in an unnatural record of its activity.
Recalling this “Year of the Wildebeest”, I vividly remember days of blazing summer sun on the vast savannas, interspersed with cool, moonlit nights, when I would lose sight of a marked animal. This sometimes occurred when predators appeared on a hunt and the scene changed from one of placid grazing to panic as lions or spotted hyaenas created chaos among the herds. At other times, during the chill of winter’s long nights, I became so tired that I began falling asleep between bouts of recordings. Bleary–eyed and numbed to the bone I would return to Okaukuejo as the sun’s watery rays spread across the plains. I consoled myself with the thought that, at least, I had gleaned another 20 000 or more seconds from the wildebeest’s diary.
After a year the statisticians pronounced themselves satisfied with the quantity and the physiologists were satisfied with the quality of the information they had. It required a further year to analyze, interpret and produce a voluminous report. When it was ready it told the story that a wildebeest needs 10% more energy just to stand resting, compared to lying. Grazing needs 50% more energy than resting and walking consumes 70% more. The energy crisis in wildebeest occurs when they have to sprint for their lives to escape a hunting lion. This is when they use up to 8 times as much precious energy than when they were just “ticking over” at rest. Small wonder that wildebeest spend a very small percentage of their day on the run: only 0,6% or nine minutes to be exact.
The four basic requirements that a wildebeest must have to survive in nature are food, water, protection against the extremes of weather, and protection from predators. The painstakingly compiled diary reflects that a wildebeest spends 53% of its life resting and 33% foraging for grass. Enter a further 12% for movement, including the daily trip to a waterhole or perhaps a brief gallop. Less than 1% is spent actually drinking. Adding these entries, we see that nearly 99% is accounted for. What about the remaining quarter–of–an hour? Well, let’s be fair. If you or I had our day fully booked just to stay alive, wouldn’t we want to indulge in a little social activity? Wildebeest do just that. So, next time you visit Etosha and see two wildebeest bulls facing each other and pawing the ground or chasing a herd of comely cows, be understanding of their apparently comical behaviour. Remember, if your diary was 99% booked by earning your living, would you not want to enjoy yourself at a party now and again?
Text by Dr. Hu Berry
Originally published in “Flamingo”: June 2004
More than half of a wildebeest’s life is spent resting, but being social animals, they too enjoy a little get–together.
What name do you give to a number of lions living together? Easy – there is one collective term known to most people – a . Why this designation? Its origin is obscure but probably relates to the so-called King of Beasts’ regal appearance. Over time I have found words describing groups of a variety of animal species. Animals of course include all vertebrates, namely mammals, birds, reptiles, amphibians and fish, plus the vast array of invertebrates such as insects. The result makes interesting reading and sometimes displays imagination that is difficult to interpret.
TThere are the easy ones, like a flock of sheep, a herd of cattle or wildebeest or kudu, a pack of wolves or hounds or a litter of puppies. Others are less known – like a skein of flamingos or swans or wild geese, while domestic geese merely qualify for a gaggle. When seals haul out onto their favourite beach or island they constitute a rookery and the fish they eat will be a shoal. Of course, if fishermen catch the same fish in a net, they will automatically change their name to a catch or haul. The lowly donkey, when used as a draught animal, will simply be a pack. Harnessing two or more horses or oxen together to do man’s bidding will make them a team. If, on the other hand, you were to muster them into moving in a definite direction, they would become a drove. Elevating the same horses for pleasure riding or racing or breeding, the owner would not dare to do less than to refer to them as a stud. Ordinary birds and insects moving together are a flight but if bees and locusts do the same thing they must be called a swarm. The same bees will naturally change to a hive when they return to their nest. This word nest is reserved for a number of ants and rabbits that inhabit the same place. If you breed chickens, you will have produced a brood.
Less common descriptions are when whales or porpoises surface from a dive into the ocean depths. They will re-enter the world of oxygen by breaching in a school or gam or pod. Incidentally, amphibious hippos too live in a pod. The shotgun-bearing hunter will use his spaniels to flush a covey of francolin or other game birds. If he were to hunt quails, he would search instead for a bevy of these tiny, feathered forms. He who suffers the depredations of monkeys in his fruit trees should use no other adjectives than troop when surveying the damage wrought by these nimble nuisances.
Still easy on the tongue? Let us enter the world of the rich. A man who can afford to decorate his country estate with the magnificence of peacocks will casually refer to the muster that wakes him and his servants with raucous, early morning shrieks. He will, of course, not house the common crow on his land but will, instead, refer to the building of rooks that caw from the lofty beams. This wealthy person will possess a clowder of selected cats to keep the rodents at bay in his barns. These felines will regularly produce a kindle of kittens, much to the delight of the landlord. Naturally, he will occasionally take to the rolling fields to hunt the down of hares that attempt to escape his swathe of dogs and gun. The really wealthy scoff at these lower pursuits and instead kindle their pleasure by keeping a caste of hawks in their stables. Of course, these prosperous persons may suffer sleep disturbance when a nightly chorus of frogs chimes from their extensive fish ponds.
Moving on to the realm of wild beasts – some astonishing words appear to describe groupings. Seldom moving together, except at mating and when the female is raising cubs, Africa’s ultimate predator the leopard moves in shades of silence. Solitary and secretive, the Prince of Stealth is an embodiment of feline beauty. It has the widest distribution of any wild cat species, ranking second only to the domestic tabby in its occurrence. Nevertheless, a sighting of two or more leopards together is rare and when this occurs the viewer can claim to have seen a leap of leopards. The cheetah is also referred to as the Spotted Sphinx and, like most other large cats, is a loner except when mating and raising cubs. Sighting a group of cheetahs together is more likely than in the case of leopards. This can be a number of males when they, like lions, form a coalition, which is a partnership that favours co-operative hunting. In the case of seeing a mother with cubs the lucky observer can also claim to have seen a chirp of cheetahs because of the mother’s habit of calling her offspring with a series of birdlike chirps. Cheetahs together are also known as a blur, referring to the swiftness of their stride, which reaches a velocity of 110 kilometres an hour or 30 metres a second. Relics from a bygone era when strange beasts roamed the savannas of Africa, the present day square-and hook-lipped rhinos resemble lumbering tanks of muscle. No one wants to be in the path of a rush of rhinos. Naturally, when watching a tower of giraffes at a waterhole, you will wonder how many vertebrae they have in their 2 metre-long necks. Surprisingly, the number is 7, exactly the same as us humans. Having pondered this anatomical aberration, you spot a sounder of warthogs as they approach the waterhole with a no-nonsense attitude, their tails held in antenna fashion.
Enter the elephant – Lord of the Beasts – whose society is controlled by a matriarchal lineage consisting of complex relationships. The family unit is one adult cow with as many as 30 sons, daughters, grand daughters and great grand daughters. When more than one family unit combines, a bond group or kin group is formed that can number up to 150 pachyderms. During the rainy season bonded or kinship groups may merge and form a formidable clan.
These descriptions portray our interest and interpretation of the images that the animal world creates in our perception of their forms and the manner in which they function. Our words reflect our planet’s rich animal life and with time this vocabulary will surely increase.
Text by Dr. Hu Berry
First published in “Flamingo” June 2005
Wind is air in motion. There is no wind on a frosty winter’s sunrise over the Khomas (‘hilly’) highlands of Namibia. Reaching over 2 000 metres into the atmosphere, this elevated plateau was uplifted hundreds of millions of years ago during the turbulent birth of Africa. It now forms deeply incised valleys and is where the coming wind of the day gains strength. Nurtured by high pressure cells formed over the Kalahari Desert far to the east, the wind begins to flow across the undulating mountain savanna. Hillsides, whose crop of silver grasses stood motionless under the chill of starlight, begin swaying in rhythm with the infant wind as it gains vigor, flowing westwards to the abrupt rim of the Kalahari Basin. Below the ragged lip of the escarpment lies the Namib Desert, still cold from the frequent fogs that are carried inland from the icy Benguela Current. As it descends the slopes, the wind undergoes a drastic transformation. Immutable laws of physics dictate that for every 100 metres it loses in altitude, it will gain 10C in heat. In addition, the scant wintry moisture it contains is sucked away until the air assumes a brittle, dehydrated quality. After a relentless descent of more than 2 000 metres, the altered wind arrives at the Namib coast, heated to a desiccating dryness of up to 400C. Coastal residents look up knowingly at the dust-laden skies and pronounce that the ‘Ostwind’ (East wind) has arrived. In this strangest of all coastal deserts, winter temperatures are often higher than the fog-drenched summers.
How does one define this invisible, essential agent of life that we call air? Held tightly against the Earth’s surface by gravity, our atmosphere delivers exactly the right balance of gases in the proportion of 78% nitrogen and 21% oxygen for us to live. Traces of other gases, infused with water vapour, constitute the remaining 1%. Unfortunately, one of them, carbon dioxide weighs heavily on the Earth and on our minds. This ubiquitous gas has reached levels that make prominent scientists refer to the ‘crashing climate’. An ominous warning about the 7 Gigatonnes (seven thousand million tonnes) that our industries, aircraft, automobiles and homes spew into the air every year came from the International Energy Agency, Washington DC in 2006. It reminds us that climate change isn’t some vague future problem – it’s already damaging the planet at an alarming rate’. Based on indisputable research, we are informed that Earth’s surface temperatures are most likely the warmest they have been in the past one million years. Humans have not before lived in a world this warm…..and we simply do not know, because we’ve never been there before, what the ‘tipping point’ is. When the environmental decay we are causing gives way to sudden and self-perpetuating collapse of ecosystems, we will know…..but it will be too late. Pump sufficient carbon dioxide into the sky and it may behave similarly to the 100th degree Celsius, which suddenly turns hot water into steam. If the Antarctic ice were to melt, it holds enough water to raise sea levels more than 65 metres, according to the United States National Centre for Atmospheric Research in Colorado. The rare gases remaining have unusual names, derived from Greek, like argon (‘idle of work’), helium (‘from the Sun’), hydrogen (‘water-forming’) krypton (‘hidden’) and neon (‘new’).Spare a thought for the traces of ozone, which occur throughout our atmosphere. Named after the Greek word ozein, for the peculiar smell generated in lightning storms, it is produced by ultraviolet rays reacting with oxygen. This makes it an unstable combination of ‘super oxygen’ that magically filters out most of the Sun’s harmful ultraviolet rays. Ironically, we humans need them in tiny doses to produce vitamin D. Too little ultraviolet on our skins and our health declines; too much and we develop skin cancer – it is a fine balance. The atmosphere provides a protective screen against invisible, but potent solar winds, which speed 150 million kilometres from the Sun across the ether in less than 10 minutes. This incoming solar radiation has the naked energy to destroy all life on Earth. Our air shield has no abrupt cut-off. It thins and fades away imperceptibly into space. Nevertheless, if a person ascends above 100 kilometres, he or she is dubbed an astronaut. Below this altitude we remain mere aeronauts. The hazardous, heat-generating re-entry of spaceships becomes noticeable at 120 kilometres, but for general purposes the Karmen line at 100 kilometres altitude is frequently used as the starting point of space.
Strange as it may seem, air has a mass or weight (about 5,000 trillion tonnes in total), resulting in what we know as air pressure. The density or mass of air at sea level is about 1.2 kg per cubic metre. Nearly two-thirds of this is below the summit of Mount Everest and three-quarters lies beneath the intercontinental jet liners that ply the world’s skyways, 10 kilometres above sea level. In the rarified regions above this, we witness the ghostly effects of the Aurora Borealis or ‘Northern Lights’, displaying phantom-like curtains of gas in the heavens of the high latitudes. Within the 1000C range of extreme temperatures that have been measured on Earth, from minus 500 C to plus 500C, our planet has a livable but cool surface average of 140C. Indeed, it is this span of cold and heat that generates winds which have shaped, and will continue to shape, the planet’s surface by aeolian processes. Named after the mythological Greek God of the Wind Aeolus, particles like abrasive sand both erode and leave deposits. Moreover, frost and precipitation of fog, rain and hail persistently pockmark the surface.
As Earth enters an uncertain climatic future, we take with us the knowledge that we are living in the ‘third atmosphere’. The first two, formed more than 3 to 4 thousand million years ago, were so noxious that present life forms could not exist. If people persist, in their ignorance, to pollute the air, a fourth atmosphere will develop, erasing life as we know it. Fortunately, Namibia boasts one of the cleanest atmospheres in the world. Let us therefore hope that the clean, cold, air that pervades the wintry Namibian nights and the hot desert winds remain as pure as they presently are.
Text and photos by Hu Berry