Ourebia ourebi

Family : Bovidae

 

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Text © Dr. Gianni Olivo

 

 

English translation by Mario Beltramini

 

 

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The Ourebia ourebi is a small antelope reminding a gazelle © Mazza

The name “Oribi” comes probably from a word of the language of the Khoikhoi, which means dwarf antelope, probably, because the first descriptions of this small antelope, present also in central and western Africa, occurred in the zone of the Cape.

The Oribi ( Ourebia ourebi - Zimmermann, 1783, family Bovidae ), belongs to that group of species, all of small dimensions, which is defined “tribe” of the Neotragins, group including, in addition to the Neotrages or pygmy antelopes ( Neotragus pygmaeus, or Royal antelope, Neotragus moschatus, or Suni, and Neotragus batesi or Bates’s Pygmy antelope ), the three species of Racipherus or Grysbok, the Rock jumper or Klipspringer ( Oreotragus oreotragus ), the Beira ( Dorcatragus megalotis ) and, finally, the various Dik-diks ( Madoqua ).

Morpho-physiology

Among all the aforementioned species, the Oribi is, along with the Klipspringer, the most similar, at first sight, to a “gazelle”, due to its extremely graceful and proportioned look, the long legs and the slender silhouette, which suggest agility and velocity.

The body, even if being an open zones antelope and therefore relying often on the run fro getting away from danger, has some analogy with some “diving” antelopes (duikers, bushbucks, etc.), or with our roe deer, with hind limbs slightly more developed than the fore ones, and also the profile of the back looks slightly higher backward.

The legs are short and slender, and same can be said for the neck, whilst the tail is rather short but “bushy”. The ears are big, but not as the steenbock and less rounded, tending to the shame of an elongated ellipse. The head of the male is adorned with two straight and sharp horns, 7 to 20 cm long and usually annulate only at the base.

The colour varies remarkably, depending on the geographic zone, but usually it tends to the reddish or the light brown, up to the yellowish, with white ventral parts, inner thighs and legs.

Also the rump is white, and on it we see the contrast of the black colour of the tail, furthermore, there is also a thin white line over the eye and also the chin is candid. A useful recognition element is the characteristic and evident dark dot placed under the ear, which is noted immediately by the observer, and at times is also well visible the red colour of the naris.

As I was saying before, the tail is black and creates a neat contrast on the white of the rump, as it can be utilized a “follow me” signal, mainly for the benefit of the young, or of the male, in the case of a pair, as, in case of escape, the female usually walks ahead and the male follows.

Great and functional pre orbital glands are present in the males, whilst in the females they are not evident, but may exist in a vestigial form.

At the level of the dark marks present under the base of the ears, there are glands able to spread in the air odorous particles, while other glands are placed at the level of the foot (carpal glands) and in the inguinal folds.

Zoogeography

The oribi is present in the sub-Saharan Africa in a vast belt going from Senegal to the southern part of Sudan and part of Ethiopia, passing through the Central African Republic and Cameroon, but excluding the Horn of Africa.

It maybe found in Tanzania, Zambia and Zimbabwe and in part of Mozambique, Angola and South Africa.

Habitat-Ecology

The typical habitat is the open grassy savannah, but preferably mosaic-like, with zones of thick bush which may offer shelter in case of danger. It avoids the prairies of high grasses, which would reduce the visual field and is, in the dry season, the first herbivore to appear on the place of the bush fires, which reveal to be a quite useful occurrence, because, immediately after the passage of the fire, from the ashes comes to life a very green, extremely nutrient, grass.

The oribi takes great advantage of this, when the “shoots” of grass are still so low to be insufficient for the great “grazer” antelopes and the buffaloes.

And, talking about “grazers”, that is about herbivores which feed on growing grasses, in contrast to the “browsers”, which take off leaves, fruits, berries and twigs from the plants and the bushes; it is interesting to note that the oribi is the only neotragin which is mainly a “grazer”.

I have said “mainly, purposely, as, in effect, also Ourebia may switch to the “browsing”, especially in the dry season, during which it takes advantage of the evergreen leaves of bushes and low plants, in addition to the grass generated by the passage of the bush fires.

Wherever possible, this antelope prefers definitely wet areas, where it may find green grass also during the driest periods.

It is an antelope relatively independent from the water, which may get from the food, even if, obviously, it drinks. Also the mountain prairies are often colonized, also because, quite often, they have that mosaic of grassy spaces, interspersed with bushes and ravines, which offer food and shelter.

The density of population reaches the maximum where are remarkable concentrations of great herbivores, such as buffaloes, hippos, zebras and also livestock, which contribute in keeping the level of the grass low enough to allow security and visibility to the oribi, without forgetting the possibility of taking advantage of the alarm-effect of many other herbivores, in the case of a predator approaching. The young relies, on the contrary, in the immobility and the invisibility, between the grasses or inside a bush.

The defence from the predators is usually entrusted to a quick escape, with sudden bounds for confusing the pursuer and with high leaps for better seeing who is hiding into the grass, often preceded by an alarm whistle. The developed speed is remarkable, in the order of the 50 km per hour.

Usually, after 200 or 250 metres, the animal stops and turns to control, unless resuming the run if it realizes that the foe has not given up.

The oribi is a territorial animal and the males tend to take possession of a territory which they share with one, two ore three females, territory often very wide if related to the modest size of this antelope, even more than one square kilometre.

An observable feature, especially after the bush fires, is a tendency to form groups, in any case much unstable, and without any liaison.

The bush fires have, for the oribi, positive aspects (i.e. tender grasses), but also negative (the thick shrubs, utilized as hiding place, are spoiled and burnt), and for this, in these periods, being this antelope an animal which may rely on a quick escape, the escape distance increases quite a lot and the fact of being associated with other commensals means more eyes and ears and therefore a greater security.

However, the instability of such apparent association may be well noted in case of the appearance of a danger: each one for himself and God for all, as the proverb say, and by then we shall see the various individuals fleeing in all the directions.

The sexual behaviour seems to be almost the connecting link between the monogamy and the polygyny.

The pair bond is less strict than that observed in the klipspringer or in the dik-dik, but a little more than that of the Steenbock ( Raphicerus campestris ).

In all my observations on the klipspringer, male and female tend to keep very close, whilst in the case of the oribi the two companions, often, are quite parted, but this might also be due to another fact: the extension of the territory and therefore the time devoted to control and defend it and the meticulousness with which the male patrols its property, leaving marks every where, this means also being extremely busy, just like those husbands the wives never see because always travelling for work.

In any case the pair (or the…triangle, if the females are two), keeps in touch thanks to the abundant quantity of available odorous markers, something like having an olfactory version of the mobile phone. In particular, the male rubs the pre-orbital glands on shrubs and stems all along the perimeter of the territory, often, every few metres.

The sound signals consist in a tenuous and short fluting whistle, repeated a few times, and also these maintain the contacts between the members of the small “family” group, whilst a louder and “harder” whistle is an alarm signal.

A third system of communication, maybe the most characteristic, is the “faeces dance”.

The female lowers on the rear for urinating or defecating, as visual appeal system for the male, and this one usually rushes and exhibits in that dance of the droppings typical of this species.

The ceremony begins with sniffing the genital zone of the female, then the male moves away of a few metres and begins to mark the stems of grass with the pre-orbital glands, then sniffs for long time the faeces or the urine of the partner and “hoes” showily with the leg, and then lays, in its turn, the own faeces together with those of the females or urinates in the same place.

In reality, also if in other species of Neotragins the female lies down blatantly while defecating or urinating, as an appeal, and the male does the same (before or after the female), but the “hoeing” and the “marking” in association with such a gesture is typical only of the oribi.

The territoriality is expressed also by the female who, more than in other species, defends vigorously the territory against other antelopes of the same sex, but not only: the liaison female-territory is such that, even if the male dies, the female remains in the same area for all the life, and often the male is replaced by a “stranger” which settles in the vacant masculine “place”.

The sons are sent away by the male once they reach that age we might define as adolescence, when the master realizes that they might become potential competitors. If the young does not accept to leave, at times is killed or seriously injured by the sharp horns.

The activity is essentially diurnal, but, at least in a couple of occasions, one of which in Tanzania and one in central Africa, I have encountered oribis grazing at night, on the other hand is commonly accepted the fact that there is still a lot to discover about the secret life of this animal.

It is amusing to observe the exhibitions of two males with neighbouring territories, when they meet by the...boundary: both assume a menacing look consisting in an erect posture, arched back, lowered neck and horns kept vertically, while the tail raises. Both have a lot of trouble to mark up like mad, everything available, to then withdraw behind the own lines, after having shown the entire arsenal they have. If one of the two, however, or if a stranger, dares to pass the boundary, the owner assumes the same posture, decidedly menacing, but advancing towards the foe and this may herald a serious attack. Fighting to death are rare, also because the weaker (or the less motivated, usually the invader), usually flees, but may happen, usually resulting in serious injuries of the death of one competitor (the sharp horn easily penetrates the abdominal cavity, and if not lethal at once, causes death by internal bleeding or peritonitis in short time).

Reproductive Biology

Even if the oribi has not a real seasonality, the peaks of the births happen during the rains and therefore, between October and December in austral Africa, and from May to July in central Africa. The female becomes sexually mature before the year of age, the male around the fifteenth month of life and the gestation is long for such a small animal: about 7 months.

After the birth, the cub remains hidden for at least one month and only by the 3 months it follows the mother in all its displacements, then, the year of age gone, usually is thrown out from the house by the father, before it may begin to become a potential competitor, and, if it does not agree to go with the good, it easily convinced with the bad manners and, at times, killed: this might not please someone, as nowadays a certain diffused animalism is tending to consider all animals as good and gentle, but in reality it is not by sure matter of wickedness, but of instinct of survival and of obedience to one law of the Nature, whose rules are at times apparently ruthless but which have always, as final intention, the conservation of the species.

Common names

English, German, Spanish: Oribi; Afrikaans: Oorbietjie; French: Ourébi; German: Bleichbockchen; isiZulu: Iwula ( plural amawula); Camerun: Giabaré; Swahili: Taya.

 

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The photographic file of Giuseppe Mazza

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