Every
visitor to the African bush wants to see an elephant. Alongside their
intelligence, intense social ties, vulnerability to emotion and phenomenal
memories, they’re physically extraordinary too, as Travel Africa
reveals.
Size – the secret to survival
The elephant’s
gargantuan proportions determine almost everything physical about it. Size has
enabled it to survive over the millennia. Depending on maturity, African
bull elephants stand between three and four metres at the shoulder and weigh
between five and six tons. That’s more than the combined weight of 100
human adults!
Possibly the largest was an Angolan bull that stood at
just over 4m, was 9.8m long and supposedly topped the scales at 10.9 tons. Its
skin alone weighed 1.8 tons and was later mounted in the Washington Museum.
Another, said by rangers to be nearly as big, was Zhulamati (Shangaan for
“taller than the trees”). He had one tusk so long it rubbed on the
sands of Zimbabwe’s Gonarezhou Reserve. Doddiburn, the well-known bull in
the Bulawayo Museum (also in Zimbabwe), is thought to be the second largest
mounted specimen in the world. He measured over 3m at the shoulder, weighed 5.5
tons and carried tusks of over 40kg each. He is a little bigger than the
specimen from Nyasaland (Malawi) that was mounted in Britain’s Natural
History Museum just after the start of the last century. However most elephants
roaming the plains of Africa today are of lesser stature, as are the females of
the species — they weigh in between 2.7 and 3.5 tons and stand about 3m at
the shoulder.
To cope with this bulk, the elephant’s skeleton is
extremely rigid and his movement stiff. The short, thick, muscular neck, needed
to support the elephant’s gigantic head and tusks, is very limited in its
movement. Muscle power alone won’t hold the tonnage, so its legs are stout
columns of nearly solid bone positioned almost vertically beneath and on the
corners of the torso — like the legs of a standard table. Although it
cannot run, it walks efficiently at about 5km/h and can “speed
stride” at about 40km/h. Each step sends a three ton shock jolting through
the leg, but a wedge of special fatty tissue in the foot absorbs the impact.
This fleshy pad enables the sole to splay on landing, thus distributing the
animal’s weight over a larger surface area.
Standing, the
elephant’s bulk rests mainly on the thick cushion behind the toes. The
latter point straight forwards but are fairly rudimentary and cased in a common
skin. Not surprisingly, elephants cannot jump and a ditch wider than a step is
an impenetrable barrier.
Ivory — the “white gold” of rapacious
humans
Most African
elephants, male and female, sport tusks, which are important tools for
chiselling, debarking, digging, rooting, levering, breaking, ripping,
displaying as weaponry and stabbing. Tusks are, in fact, modified incisor
teeth, not canines as might be expected. A large part is embedded in the skull
but measurements along the curve from tip to point of entry have recorded
lengths of 3.5m. Most animals sport less than half that. Likewise, whilst a
tusk weight of 106.8kg was once recorded, the majority of elephants carry
considerably less than 50kg per tusk. For ivory exports from Zimbabwe for the
period 1987-92, the average tusk weight was only 19kg.
Tusks continue
to grow about 10cm per year throughout an elephant’s life, so broken tips
are replaced. However, continuous wearing down and breakages mean they never
achieve full potential length. The tusks of the jumbos that dig salts in
Uganda’s Mount Elgon caves, for example, are particularly short and stumpy
as a result of working the hard cave walls.
The tusks of cows tend to
be more slender than those of bulls. A few animals have been found to sport
four tusks, but more common are tuskless specimens. Tusklessness may be a
natural selection process evolved as a way to combat poaching. Genetic
tusklessness seems to be on the increase. In some parts of Africa up to a third
of calves born will never carry these useful tools. In less than half a
century, mankind has perhaps forcibly accelerated a change that should take
thousands of years of evolution. The consequences of tusklessness on an
elephant’s behaviour, especially feeding, and the subsequent ecological
effects, remain to be seen. However in the Zambezi Valley, where tusklessness
has increased, the animals are noticeably more belligerent.
In
cross-section, the tusk exhibits lines which radiate from the centre like a
star — the only mammal tooth to do so. This feature makes it more valuable
than the tusks from animals such as the warthog: in texture, the elephant tusk
is soft enough to carve yet hard enough to buff to a shine. Tusk excellence
as a carving medium or prestige value as a hunting trophy are not the only
reasons for killing elephants. In the past, powdered ivory featured in enema
preparations, whilst ivory shavings were used as a jelly-making ingredient in
19th century England. Burnt ivory, sometimes called black velvet, was used to
colour paint, inks and human hair.
Carved ivory thrones are mentioned
in the Bible. Kings and queens throughout history also esteemed them. Most
notable, perhaps, was that laid with gold upon which Suleiman the Magnificent
sat. Tutankhamen’s tomb housed a casket inlaid with over 40,000 pieces of
ivory and Caligula built an ivory stable for his horse. In the 20th century,
bagpipe joints, piano keys, billiard balls, rosary beads, and a host of
figurines and trinkets have been fashioned from ivory.
The eating
machine
The elephant is
a biological eating machine with a colossal appetite: up to 200kg of vegetation
may be consumed each day. Tender new grass is relished but amongst the hundreds
of different plant species on their menu, staples include leaves, reeds, seed
pods and herbs. Living in groups, they cannot afford to be discerning diners:
there just wouldn’t be enough to go round. The elephant’s diet,
therefore, comprises a lot of low quality food — tough tree bark and
coarse shrubs.
Elephants will graze by preference, but this is only
possible when grasses are plentiful (in the moist growth phase). When grasses
dry out and become fibrous, the animals gradually switch back to browse. They
are particularly partial to fruits such as vegetable ivory and wild almond.
Given the opportunity, they may gorge themselves to the point of intoxication
on fermenting marula fruit.
Being able to stretch up to 6m, elephants
can pluck fruit and leaves from treetops beyond a giraffe’s reach. They
are connoisseurs of agricultural crops, particularly favouring rice, maize,
millet, sugarcane, palms, bananas and fruits — often staple foods of local
communities.
To get the nourishment they need, elephants spend up to
18 hours each day eating. This leaves only a few hours in which to sleep each
night. This they normally do standing up. Bulls have been seen propping
themselves against termite mounds; calves generally lie down to sleep.
The elephant chews its food by grinding the lower jaw against the upper, using
a forward and backward motion. Masticating large amounts of rough vegetation
means phenomenal wear and tear for teeth. To cope with this, the elephant has a
conveyor belt of molars made of a series of flat, transverse plates, each
growing independently from its own root. The whole is joined together by cement
to form great blocks of enamel and dentine about 30cm long. As one set wears
down, another larger set moves forward to replace it (no more than two sets
being in use at any one time). The sixth and last pair, weighing up to 4kg
each, comes into place at about 40 years of age. When finally worn out, about
20 years later, the animal dies of a combination of old age, malnutrition and
starvation.
The elephant’s massive, rigid frame means that it
does not lower its head to eat. It relies, therefore, on its flexible trunk to
graze the grasses below and browse the boughs above. The trunk evolved from a
fusion of the nose and upper lip muscles into a single organ of great mobility,
over 5m long. It is the most versatile limb in nature, even more dexterous than
the human hand. This boneless extension contains over 100,000 interlacing
muscle units, some running longitudinally and others radiating outward from the
centre. It ends with two opposable finger/thumb-like tips (the Asian elephant
only has one). Here it bristles with thousands of whiskers and is sensitive to
the slightest touch. Each bristle is attached to a single nerve that travels
the entire length of the trunk before feeding directly into the brain. This
makes the tip 10 times more sensitive than a human finger. With such equipment
the elephant can pick up a single peanut, strip leaves from a stem in one
sweep, pull plants from the ground and convey food and water to its mouth.
The trunk, however, is not just the elephant’s fork and spoon. It can
siphon with suction strong enough to draw up nine litres of water in one go and
then spray it (or dust) over its body. To get rid of ticks and parasites,
elephants bathe themselves at least once a day if possible. Trunkfuls of water
are blown first behind the ears, then along the flanks, between the legs and on
top of the head. A mud wallow and/or dust bath follows. The latter leaves them
tinted with the colour of their surroundings.
The trunk can also
produce a trumpeting, bloodcurdling scream that can be heard miles away. It can
be extended, retracted, bent, twisted and turned in almost any direction, its
senses allowing it to determine the shape, texture, temperature and scent of
any object.
An elephant’s trunk is a barometer to its mood: it
hardly ever stays still. When it’s curled up, the animal is relaxed (each
individual has his own idiosyncratic way of doing this). When the trunk is held
high, the elephant is alert; when it is tensed up the beast is feeling
stressed, and it is curled back when danger is sensed. The ancient Romans
considered the trunk a culinary delicacy.
At the fount of life
To aid digestion, elephants
need up to 270 litres of water a day. This is sucked into the trunk, which is
then curled and tipped to release the contents into the mouth, a technique
acquired only after about six months of age — and plenty of practice!
When surface water is not within half a day’s march, elephants will
use their tusks and trunks to dig wells, usually in dry riverbeds or where they
sense sub-surface deposits. These wells, normally about a metre deep, enable
many other creatures to survive in drought areas. Animal action around the well
enlarges it.
Elephants dominate at waterholes, sometimes driving off
and occasionally even killing intruders — buffalo and giraffe included.
Here they drink, then enjoy bathing and mud wallows, after which they often
shower themselves with dust and rub against trees and boulders. All this helps
remove ticks and other pests, keeps the skin in good condition and aids
cooling. The pans are broadened as tons of soil are removed on the backs of
elephants.
Elephants can swim well, maintaining a speed of about
1.5km/h for up to six hours. Amazingly, in the late 1970s, two bulls swam from
Zimbabwe’s Spurwing Island across Lake Kariba to Kariba town, a distance
of at least 25km. These 20-year-olds took turns to rest, one placing his
forelegs on the haunches of his companion in front. Apparently their
24-hour-long trip followed an old elephant migration trail that had been
covered by the lake for 25 years!
The elephants’ remarkable
proficiency in water is cited in support of research evidence that they were
originally water creatures. Studies of embryos show that the lungs, kidneys and
testes of the elephant all develop in a manner similar to many aquatic animals.
Maybe the reason for the Kariba crossing goes deeper!
Biological
air-con
Bathing and
squirting water behind the ears certainly helps to cool the body, but it’s
not enough. Because they are large, elephants have a small body surface area
relative to their weight, and they don’t have sweat glands as they would
lose too much vital body water. So under the baking savannah or desert sun,
when temperatures can soar to 50º C, they are liable to cook.
To
combat the overheating problem elephants are endowed with two ultra-efficient
heat-dispersing mechanisms: their ears and their skin. The African
elephant’s ears are larger than those of the Asian elephant and when
spread in display produce a frightening 3m front. They make up one-fifth of the
elephant’s total surface area. The ears are covered with paper-thin
“skin” and their backs are supplied with hundreds of blood vessels.
These are close to the surface and as the ears are rhythmically flapped, the
circulating blood is cooled. Elephants often squirt water behind their ears to
accelerate the evaporative process. Every 20 minutes, an elephant’s entire
blood supply, nearly 680 litres, passes through the ear’s intricate
network of veins and capillaries.
An African elephant’s skin,
despite being about 2.5cm thick, is quite sensitive. It is also almost hairless
and more wrinkled than that of the Asian elephant. It is pitted with deep
channels and pockets, whereas that covering an Asian elephant is more like an
open honeycomb. In effect, the skin is almost twice as big as it needs to be:
stretched out, it would cover about 24m2. The wrinkling enables the elephant to
hold more than 10 times the amount of water that would remain on a flat
surface, and to dissipate heat more efficiently.
Another cooling
device lies deep inside the elephant’s throat, where a special pouch holds
water that can be siphoned out and sprayed over the baking body when far from a
waterhole.
Making
sense of the world
Elephants cannot turn their heads much to the side. Their eyes, small and
hidden behind long bushy eyelashes, are also buried in folds of skin thus
further limiting their vision. To make matters worse, the eye is made up mainly
of rods (the retina’s light collecting cells). Whilst these function well
in low light, they get overloaded in bright sunshine and their large number
restricts the number of cones (cells that process colour and focal depth). As a
consequence, elephants don’t register detail. The view may be dim but
shape, gait and smell — a much more powerful sense for bringing the world
into focus — identify individuals.
Elephants live in a world of
complex odours that lie beyond human senses. The nasal lining of the trunk
contains 20 million scent receptors — over three times those possessed by
humans. These feed the brain, where nearly two-thirds of its capacity is used
in processing odours. Thus the elephant creates a discerning olfactory picture,
one that is also very discriminatory: elephants can detect and identify
particular individuals from some distance, and interpret emotional states such
as excitement, fear, stress and sexual receptivity.
All elephants
secrete a thick, pungent substance called Temporin. Excitement or fear
stimulates its flow from slit-like temporal glands (modified tear glands)
located either side of the face midway between eye and ear. When this gland
functions, the forehead swells, a dark oily substance oozes conspicuously down
the side of the face, and there is a marked rise in aggressive behaviour. The
odour varies individually and is secreted year round by cows but only by bulls
in musth, a Hindi word meaning Madness. It first appears at about two years of
age, peaks in males at about 35 years, and finally subsides around the
animal’s half century.
The most pungent of elephant odours,
easily detectable even by humans, is that of a bull in musth. There is a marked
rise in the production of the male hormone, testosterone, the testes being
carried internally next to the kidneys. A bull’s dangling penis assumes a
green hue as it constantly dribbles, leaving a trail of extremely acrid urine.
Only when thus ready will the bull seek out a mate within a family group. Bulls
come into musth at different times of the year, so cows who come into season
for a few days every three months (if not pregnant or lactating) can be
serviced.
The mating game
Cows reach sexual maturity around the age of 12, mate and
are already first-time mothers by 16. Females in season, identified by the loud
oestrus rumbles they utter, are tested for readiness by males who put their
trunks to the cow’s vulva and collect and taste a sample of her urine. In
the palate is a special organ sensitive to the hormonal content of the urine
and thus to the cow’s reproductive state.
When two musth males
contest a female, an intense, aggressive battle ensues, forehead to forehead.
(Male foreheads are more rounded than those of females.) The confrontation may
last five or six hours, the victorious bull being rewarded with ready
compliance from the cow. By co-operating with the strongest specimen around,
she ensures the quality of her offspring.
Cows can outpace bulls if
they wish, and do so if approached by an unwelcome suitor. Having chosen a
male, a cow stands still when touched — usually by the bull laying his
trunk along her back. He then mounts by heaving himself onto his hind legs and
squatting slightly as he works his forelegs up the female’s back. By
hooking up his mobile S-shaped penis, he enters her. He is unable to thrust
with his body but his penis moves independently within her and copulation lasts
no longer than a minute. The act sometimes induces great excitement amongst the
herd but often is ignored.
Elephants generally part after mating but
occasionally a couple will consort for a time, paying close attention to each
other and excluding others from any intimacy. They may even separate from the
herd. If she has conceived, it will be 22 months before she gives birth.
Young at
heart
Cows give birth
standing up. The calf is born a pinkish-grey colour, is hairy and weighs about
110kg. During birth, other females from the herd often attend the mother.
Subsequently these “midwives” generally adopt a communal
responsibility towards the upbringing of that youngster. At birth the calf
is extremely vulnerable to predators, so using her foot, the mother gently
prods him to rise and join the herd. It may be an hour before he takes his
first faltering steps.
The calf suckles from the pair of teats between
the mother’s forelegs, sometimes standing on its hind legs to reach them.
For the first year, calves can pass under their mother’s body. They are
normally weaned at 18-24 months but may continue to suckle until their fourth
or fifth year. Young calves stay in constant contact with their ever-protective
mothers and remain dependent upon the family unit until well into their teens.
The emotional bond between mother and child seems as strong as in humans.
Baby elephants are born with few interconnections between brain cells and
therefore lack a number of skills vital to survival. As with humans, this sets
the species apart as the brain is more malleable and has a large capacity for
learning. Survival skills — how and what to eat and drink, how to bathe
and dust, and how to behave — are taught by the mother. In a world of
exciting discoveries, learning to control the trunk is a major challenge
requiring two years to accomplish.
Learning social skills is also
vital. The complex structure of elephant society is founded upon a subtle
hierarchy determined principally by age. Learning one’s place, acceptable
manners and how to show respect to elders (particularly the matriarch) is as
fraught with difficulties as it is for human children.
The
elephant’s extended period of learning indicates a measure of intelligence
that enables it to develop skills it uses in circuses and when working in
elephant-back safaris. Its capacity to comprehend may even equate with that of
the great apes. However, in proportion to body size, the elephant’s brain
is small, though its temporal lobes are abnormally large and well developed
— hence their remarkable memories. Wisdom appears to be well respected in
elephant society, allowing matriarchs to retain leadership after menopause.
The
matriarch
The matriarch
is the linchpin of elephant society. She determines the nature, structure and
ethos of the family unit. She decides where the family will go each day, when
and where they will pause to eat and drink, and what they will do in times of
trouble or danger.
Matriarchs supply the family unit with an
historical memory of feeding grounds and the location of seasonally edible
fruits and other dispersed features in the environment. The group’s
survival in times of drought is very dependent upon her ability to remember the
location of water, sometimes last visited several decades before. Little is
known about how elephants can recall such experiences. Possibly by memorising
basic landscape features, the matriarch may have created a mental map. Another
theory is that she navigates using a complex combination of sun and star signs
and electromagnetic fields.
Happy families
The basic family unit usually consists of several related
females and their offspring, all under the control of the matriarch or
“lead cow”. Families seldom exceed 10-15 animals, a subgroup led by a
sister or close relation of the matriarch separating and going its own way when
the group gets too large.
In places like the Serengeti, Selous, Tsavo,
Luangwa and Hwange National Parks, herds numbering hundreds, occasionally up to
a thousand animals, sometimes gather when food is abundant. Family groups
within the gathering retain their identity whilst bull herds circulate. These
loose-knit groups contain youngsters of 12-15 years of age who engage in mock
battles or “jousting” — a ritual that helps establish their
position within the group hierarchy.
Within the family, members often
touch one another. They sniff each other’s temporal glands on meeting and
greeting, and the lower-ranking individual usually inserts the tip of his trunk
into the other’s mouth. This enables him to assess mood, whilst also
showing respect. On meeting, two unfamiliar elephants will often exchange a
trunk shake, and thereby assess each other’s size and strength. Exploring
each other’s bodies, they gain a mental image that sight could not supply.
When two family groups reunite after a period of separation, their tactile
greetings are often accompanied by squealing, trumpeting, pirouetting, backing
up and excreting.
Within the family herd, a sick or wounded member
causes much agitation and apparent emotion. Those that falter may be supported
between two or more adults, whilst fallen animals will be caressed, prodded and
pushed in attempts to raise them.
Jumbo talk
Being such social animals, elephants have much to say to
each other. This they do using more than 30 different infrasonic rumbles. Most
are of very low frequency, in the 14–35 hertz (cycles per second) ranges,
but one study of forest elephants found them capable of frequencies down to 5
hertz. (It’s generally accepted that humans can hear down to about 16
hertz.) Such low-pitched transmissions are amplified through the trunk and,
running at about 103 decibels, can travel up to 8km when relatively unaffected
by trees and other obstacles. These long sound waves are below the limits of
human perception unless played back at four times their original speed. The
throaty rumbles we can hear are used for closer contact and greetings, for
which each individual has his or her own identifying signature sounds.
Infrasonic rumbles, the majority of which are made by the females, especially
mothers, are also used to co-ordinate the group’s movement, to advertise
sexual readiness and to warn of danger. It is suspected that elephants can
detect distress over long distances. It has been suggested, for example, that a
sudden upsurge in aggressiveness amongst elephants in Savuti, Botswana, was the
result of messages received a few hours after culling began in Zimbabwe’s
Hwange NP, about 200km away.
The distant rumble of impending
thunderstorms, inaudible to humans, is also infrasonic. Elephants detecting
these sounds move towards the storm hours ahead of its occurrence — an
action noted and copied by other animals parched with thirst.
Elephants also roar through their trunks, to produce classical trumpeting or
screaming when alarmed, angered or showing aggression. A charge may, or may
not, begin with a warning comprising head shaking, often accompanied by audible
trunk and ear snapping and a harsh, shrill and absolutely terrifying scream. If
this warning is ignored, the beast bursts forth, eyes red and straining to
focus on its target, ears spread intimidatingly wide, head lowered and trunk
curled under. The tail is raised tensely in anger. Despite Hollywood films,
elephant charges are vocally mute.
However, when confronted, elephants
often move away, sometimes even after issuing a warning. But when danger to
youngsters is perceived, the herd will laager, drawing up an impenetrable
shield of adults in a circle around the calves. They face out, ears spread,
heads held high and swinging from side to side, trumpeting and screaming.
Alternatively the herd may choose to run off in a tight bunch, the youngsters
shielded by the adults.
When the mighty have fallen
Like birth, death has a profound effect on the
family unit. Elephants keep vigil over dying and dead relatives, display much
emotion at death and are markedly affected afterwards. When the deceased leaves
behind a small calf, further tragedy ensues. Babies under two don’t
survive without their mother’s milk. For older orphans there is hope, as
other adults usually take care of the stricken youngster. In a few cases,
another adult has even adopted an orphan. The most devastating experience,
however, is the loss of the matriarch, for it often results in the splitting up
of the family.
Elephants exhibit a strong fascination with the bones
of their dead, but completely ignore those of other animals. They conduct a
thorough investigation: moving, lifting, rearranging and sometimes even
carrying around the remains. Some researchers speculate that, with their
incredible olfactory powers, elephants can identify the bones of departed
relatives from their particular scent. That it is often the dead animal’s
siblings that linger the longest perhaps supports such a theory.
The
dead are sometimes “buried”, trunkfuls of dirt being tossed over the
body and branches laid to cover it. Human victims of elephant attacks have
occasionally been treated in a similar manner.
Physically, humans are
worlds apart from elephants, but perhaps their emotions explain why we identify
with them so readily.
