Oribi (Ourebia ourebi)
Size:
Head and body length:
92 – 140 cm
Tail length:
6-15 cm
Height: 50 – 67
cm
Weight: 12 – 22
kg
Description:
Small, light-colored antelope
with short, straight horns and black spots (scent glands) under the ears, white
undersides and throat. Muzzle slants
steeply from forehead. There are also
dark preorbital glands in front of the eyes.
It runs away with a characteristic “rocking-horse” gait.
Breeding:
Gestation is about 7
months. Young are precocious and hide
for 3-4 days after birth. After that it
follows its mother around with occasional retreats into hiding until it is
about 3 months old at which point it joins the mother full-time. They can stand within 30 minutes after birth,
and within 5 hours are able to jump small barriers.
Where to look for them:
They are common in the open
savannah areas of the park, often mixed with herds of other antelopes. They prefer flat or gently sloping areas,
especially those where the longer grasses have been eaten or trampled by larger
animals.
What to notice:
- Oribi spend much more time scent-marking their
territory than most other antelopes.
In the picture to the right, this male is inserting the long grass
into his pre-orbital gland in the front of his right eye, and leaving a
secretion on it for other oribi to find.
You can also clearly see the scent gland under the ear on the side
facing the camera. Oribi have a
total of 14 scent glands on their bodies.
- When predators are near, oribi tend to lay down
to avoid notice rather than running.
If you are fortunate enough to watch a lion chasing prey, observe
the different reactions of the different species.
Conservation Status:
While not threatened
themselves, they rely on herds of larger animals to eat or trample longer grasses
in order to expose the fresh shoots that they prefer. Because of this, their survival depends on
the survival of habitats that support herds of large herbivores.
Lifespan: Up to 14
years.
Detailed Information:
Order: Artiodactyla
Family:
Bovidae
Subfamily:
Antilopinae
Tribe: Neotragini
Genus:
Ourebia
Species:
ourebi
My impression is that this animal has been
studied in a number of different parks, but that the variation between results
show much regional variation in behavior.
I think the information I have gathered may be too generalized, so take
all of this with a grain of salt and trust your own observations.
Habitat:
Fire-climax
grasslands with reliable rainfall or grasslands that are kept short by grazing
(by buffalo?). On floodplains, they
prefer the less waterlogged areas where they can take cover behind termitaries
or in woody growth. (Kingdon, p.389)
Avoids woodland
and bush habitats. Prefers open mosaics
with ecotones that allow for hiding.
They may be dependent on burns during the dry season that stimulate new
growth. Where fire is inhibited, they
move during the dry season to low-lying areas that still have green growth.
(Estes, p. 58)
Range/Parks:
Patchy, but
widespread south of the Sahara. (Estes, p. 58)
Food/Water:
Many varieties of
grasses are eaten, as well as other herbs and the foliage of shrubs and
trees. They will leave favored habitat
occasionally to visit known mineral licks. (Kingdon, p. 389)
Water-dependent.
(Walker, p.
146)
This is the only
“dwarf antelope” that is primarily a grazer.
They are the first to begin feeding on new growth after a burn. (Estes, p. 58)
There is some
evidence that they may be water-independent, according to Estes. (Estes, p. 58)
Breeding:
Gestation is
about 7 months. Young are precocious and
hide for 3-4 days after birth. After
that it follows its mother around with occasional retreats into hiding. They reach close to their adult size by 4
months. Females may conceive by 10
months and males become sexually active by 14 months (Kingdon, p. 390)
Most births
happen during the rainy season. Calves
remain mostly concealed for up to a month, and join mother full-time by 3
months. They can stand within 30 minutes
after birth, and within 5 hours are able to jump small barriers. They begin eating small amounts of grass
within a week. Males begin marking with
preorbitals and have achieved adult coloration by 5 weeks, but are not fully
weaned until 4-5 months. (Estes, p. 61)
Social Organization:
They are
associated with larger herbivores. The
herds of larger animals help keep grass short through grazing and trampling
vegetation and also probably draw off predation. In areas where larger herbivores have been
reduced, oribi numbers also tend to decline. (Kingdon, p. 389)
Females are
larger than males and move independently of the males. They will encourage the attentions of a
single male, and will be intolerant of other males once she has chosen her
mate. The two will each then defend the
territory against others of the same gender.
These pairings sometimes last for years.
Territories adjoin communal grazing areas. Males daily delineate territory by scent
marking plants and soil. (Kingdon, p. 390)
Most often found
in pairs or small groups. (Walker,
p. 146)
Associated with
hippo, buffalo, cattle, zebra, topi and kob. (Estes, p. 58)
Oribis have been
considered to possibly be an evolutionary link between monogamous/polygynous
mating systems and solitary/gregarious social systems. They tend towards solitariness, but after
fires they lose their cover and there is a safety advantage in herds. When startled by a predator, however, they
scatter rather than maintaining a herd identity. Herding still has an advantage for spotting
and warning about predators. (Estes, p. 58)
Tendency towards
polygyny varies by location. Ugandan
populations are about 50% polygynous. Other
populations have been found to be almost 90% monogamous. (Estes, p. 59)
Female offspring
may be allowed to remain in territory, although stranger females are chased
off. Male offspring are chased away at
adolescence. (Estes, p. 59)
Communication:
They whistle
to indicate alarm or to signal a move to another grazing area. Puffing, breathy whistles are used like
birds’ “chip calls” to stay in contact.
They bleat if pursued or captured. (Kingdon, p. 390)
Olfactory:
The females are believed to excrete “attractants”, which keep males
continually attentive. This causes the
male to scent-mark relentlessly, perhaps leading to the development of 14
different scent-glands. This scent-saturation of the environment helps avoid
confrontations between males, and also causes the female to habituate to the
male’s scent as an essential attribute of her habitat. (Kingdon, p. 390)
Female crouching after defecating will
stimulate a dunging ceremony with the
dominant male: 1. The male sniffs the female’s anogenital
region, causing her to move away. 2. The male marks a grass stem with his
preorbital glands. 3. He sniffs her deposit. 4. He paws her deposit
‘vigorously’. 5. He urinates and defecates on the same spot. The other family members may also be
stimulated to urinate and defecate on the same spot by the activity, but they
will not paw the ground or mark with their preorbital glands. (Estes, p. 59)
Activity
Patterns:
Varies by season,
predators and reproduction. They rest
longer on hot afternoons, lie up during heavy rain, and graze at night in open
terrain, especially during the full moon. (Kingdon, p. 390)
They spend about
one quarter of their time grazing, with a peak early and late in the day.
(Estes, p. 59)
Sign:
Dung often left
in middens. Track is sharply pointed at
the tip. (Walker, p. 147)
Predators:
They are preyed upon by the usual cast of
carnivore characters. Their avoidance
tactic is to lay in hiding until the predator is close, and then flush and
quickly reach a speed of 40 – 50 kph.
They often stop and look back after running 200 meters or so. (Estes, p.
62)
References:
Estes, R. (1991).
The Behavior Guide to African Mammals. Berkeley, CA:
The
University of California
Press.
Kingdon, J.
(1997).
The Kingdon Field Guide to
African Mammals. Princeton,
NJ:
Princeton
University Press.
Walker, C.
(1996).
Signs of the Wild: A Field Guide
to the Spoor & Signs of the Mammals of Southern Africa.
(5
th Edition).
Cape
Town, South Africa:
Struik Publishers Ltd.
Photo by Mark Jordahl