(Theropithecus gelada)
Amharic:
Gelada
The Semyen
highland massif is considered to be the finest scenery in all Africa and
it is for this reason, and the fact that the area is the home of the
Walia Ibex, the Semien Fox and the Gelada Baboon that it has now been
gazetted as a national park.
The Gelada is not
in fact peculiar to the Semyen as is the exclusive Walia Ibex, but they
are more numerous here than in their other habitats Some live at Debre
Sina not far from Addis Ababa and others at Debre Libanos on the way to
the Blue Nile; there are also small populations in the Mulu and Bole
Valley gorges. But in the Semyen there may be as many as 20,000, and
troops of 400 together may be seen. They do not molest humans and, more
surprisingly, the local people do not molest them. Thus they are very
tame and will allow humans to approach quite close to the troop before
moving nearer to the cliff edge.
The Gelada was
discovered in 1835 by the explorer Ruppell, who nan;ed it by the local
name used by the inhabitants of Gonder region where he first observed
it. They are not difficult to study as they are very tame, however,
little interest was shown in them until recently, when Patsy and Robin
Dunbar made an exhaustive study of their social behaviour. The social
behaviour of the apes and monkeys is evidence of a very high degree of
intelligence and studies of their rudimentary social structures are
proving of considerable value in analysing the origins of human social
behaviour.
Geladas live
along the edges and steep slopes of precipices. They never move far from
the rim and thus their distribution is linear along the escarpment. At
night they climb down the steep cliff faces to caves where they roost on
ledges, often huddled close together for warmth as Semyen nights are
frosty and bitterly cold. Babies cling tight to their mothers even in
sleep. In the morning in the warm sun they climb up again to the top of
the cliff and spread out to feed. Geladas are mainly vegetarian, living
on herbs, grasses and roots, but they also eat insects and locusts. They
never eat meat, or hunt or kill even small birds or mammals. As a result
of this restricted diet they are obliged to spend a very high percentage
of their lives foraging and browsing in order to obtain sufficient
nutrients to survive. This may explain why they are so extremely
peaceable by nature, with very little squabbling even amongst
themselves. They have no natural enemies (except of course, Man, who
takes a fair toll with his rifle. The great mane of the adult male is
used for traditional headresses by highland warriors).
Apart from
feeding, "grooming" is their other main pastime. This entails simply
picking through each other's fur. This is not only a friendly and
peaceful occupation, but it serves also to establish bonds between
various members of a 'harem' and to cement the accepted relationships in
the hierachy, between male and female, older and younger members.
The long narrow
plateaus of the Semyen slope up- wards from the south until they end in
the dizzying precipices of the northern escarpment. This is the haunt of
the Walia, and the Gelada do not frequent these vertical cliffs, but the
rims of the stupendous gorges and ravines which bisect the plateau. The
troops tend to graze the higher moorlands, amongst everlastings, giant
lobelias and alchemilla-tussock grass. Never far from the rim, which is
their refuge when danger threatens, they disappear over the edge on to
the grassy slopes and ledges of the gorge sides. Their grazing ranks are
so arranged that the males are always farthest from the edge and thus it
is "women and children first" when they have occasion to flee to safety.
They are
comparatively large and impressive, the males being about 75 cms. (30
inches) tall without tail and twice the size of the females. Their sad
up- turned faces are marked with large ridges running from below the
outer side of the eyes to the nose. The face is dark grey with wrinkles
and very long whiskers, forming falciform tufts of light coloured hairs
projecting upwards and backwards on the sides of the head. Their
nickname, "bleeding heart baboon" stems from the bare red skin areas on
the chest, which are actual]y two triangles, and another crescent-shaped
on the throat. Both sexes have these bare places. In the female the
fleshy "beads" which surround the bare patch swell up and turn from
whitish to bright red to indicate estrous condition. In the males the
patches are always red and do not change colour. The old males have a
cape of very long hair which hangs down (to the ground when they are
sitting) and tufted tails which have earned them another name - lion
monkey. The female's mane is much less impressive than the male's. Both
sexes are a light to dark brown, the fur cape shading from one colour to
another as it moves in the mountain breezes. They are found at more than
4,500 metres (14,600 ft.) and have even been seen at the top of Ras
Dashan at 4,620 metres (15,160 ft.) where tbere is nothing fox them to
eat, so they must just go up to look at the view.
Their handsome
appearance and the beauty of their habitat is one thing, but perhaps the
most fascinating aspect of these creatures is their social structure
which is the most complex in the animal kingdom after that of man. You
see them grouped into herds of up to 400 or so individuals, each of
which is made up in turn of "harems", which are groups of from two to
eight females and young ones with one dominant male and often one
hanger-on called a "follower", who ingratiates himself with the juvenile
females, with a view to enticing them away in due course and forming his
own harem. Harem owning males do not attempt to steal each others'
wives.
Young males get
together in groups from the age when they finally leave their mothers
until they are mature enough to become a follower. These various social
groups all move and feed together, only occasionally leaving the herd if
food supplies demand it. They travel about three miles a day while
feeding, and sleep on ledges on the cliff face wherever they happen to
be when night falls.
The harem is a
very close family unit. Ninety-five percent of the social interactions
of adults are with other members of the same harem. Only juveniles and
babies cross the invisible boundaries to play with others of their own
age. Unlike the Hamadryas baboon, where the harem is kept together by
male agression, the Gelada harem is run more or less by solidarity
between the females. It is they who decide in which direction they will
feed, it is they who instantly rally together if their male should
threaten any one of them because she strayed too near another male! Only
one of the females has a strong relation- ship with the male at any
given time. But they all groom each other as well as him and thus
establish a jealousy-free harmonious relationship with each other.
For a young male
to acquire a harem of his own is quite a long and difficult process. He
starts off when he is about two leaving his mother's harem in favour of
play groups of other juveniles. By the age of three he starts playing
around with the younger members of the all-male groups, and at four he
things of nothing else but joining one (which is not always easy as the
groups are very tight and do not readily welcome new members). Having
succeeded he settles down to life as a bachelor sub-adult in his group.
When he is about five or six, he begins to show an interest in the
harems again. He doesn't want to anger the adult male of any harem so he
confines his activities to following along, occasionally grooming with
the male but mainly amusing himself with the young females - the ones
too young to cause jealous feelings in the old male. Should the old male
die or become weak, the young one will take his place, but it is more
common for the youngster just to gradually withdraw taking with him
several of the young females. This is not a sudden break - the one group
just spends progressively more time on its own. The male then sets about
getting a few more females from other harems - young females belonging
to a harem with no follower may join him before their father takes an
interest in them.
Over the years
each male has a succession of followers who take away his daughters to
form the nucleus of their own harems; a system which prevents in-
breeding. Sometimes a younger male may persist in paying court to the
wives of an older, and generally harrass him. The few fights which occur
are usually the outcome of such behaviour. The old one finally, after
trying to retain his females' loyalty and affection, may give up the
struggle. If so, he does not retire from the harem - he just adopts the
follower role and spends his retirement grooming and playing with the
juveniles.
The relationships
of the Geladas are very delicately balanced. To communicate their
intentions they have need of a fairly subtle range of signals. They have
therefore acquired a great diversity of social behaviour patterns and
vocalizations. Greater in fact than any other non-human primate. For
examp]e, where the olive baboon has fifteen contact calls, and the
colobus six, the gelada makes twenty-seven distinct noises. To hear him
speak, is as it were to listen to a foreign language being spoken. The
expressions on the face are in fact signals with a distinct meaning: the
raising of the eyebrows reveals two red triangles above the eyes - a
warning signal; the rolling back of the upper lip in a ghastly smile, a
flash of red gums and white teeth, signifies (as perhaps does the human
smile) appeasement, and thus avoids possible conflict.
So far, the
gelada is not on the endangered species list, and now that he lives
protected in at least one of his habitats, one can hope that he never
will be. How- ever, the occasional random slaughter "for fun" of these
beautiful, gentle and intelligent creatures should be curbed for obvious
reasons. |