Kobus kob (*)
Kobus kob (Erxleben, 1777)
The Kob (Kobus kob) is an antelope found across Sub-Saharan Africa from Senegal to South Sudan. Found along the Northern Savanna, often seen in Murchison Falls and Queen Elizabeth National Park, Uganda; Garamba and Virunga National Park, Democratic Republic of the Congo, as well as grassy floodplains of South Sudan. Kob are found in wet areas (such as floodplains) where they eat grass. Kob are diurnal, but inactive during the heat of the day. They live in groups of either females and calves or just males. These groups generally range from five to forty animals.
Among the Kobs of Eastern Africa, the Ugandan Kob (Kobus kob thomasi) appears on the coat of arms of Uganda, and the White-eared Kob (Kobus kob leucotis), found in South Sudan, south-west Ethiopia and extreme north-east Uganda, participate in large-scale migrations.
The male kob is robustly built and has a muscular neck and thick, lyrate horns. Females are more slender and lack horns. Males have a shoulder height of 90–100 centimetres (3.0–3.3 ft) and an average weight of 94 kilograms (210 lb). Females have a shoulder height of 82–92 centimetres (2.69–3.02 ft) and weigh on average 63 kilograms (140 lb). The general coloration of the animal ranges from golden to reddish brown and has a white throat patch, eye ring and inner ear with black fronted legs. Males darken as they mature. Males of the White-eared Kob (K. k. leucotis) which is found in the Sudd region (the eaternmost part of the kob's range), are strikingly different and overall dark; rather similar to the male Nile Lechwe, though with a white throat and no pale patch from the nape to the shoulder. Both sexes have well-developed inguinal glands that secrete a yellow, waxy substance, as well as preorbital glands.
The kob has a scattered and patchy distribution ranging from Senegal and Guinea-Bissau to Uganda, South Sudan, and south-east Ethiopia. It requires low-lying flats or gently rolling country close to permanent water with no severe seasonal extremes. Having likely evolved from a reedbuck-like ancestor, the kob is largely tied to floodplain grasslands. However, it is not cover-dependent and avoids flooded ground and steep slopes. Still, its preference for perennial grasses in early, palatable stages and its need to drink daily makes it tied to green pastures that are well watered. During the rainy season, kob concentrate in areas of short grass and higher, dry ground and keep these pastures short while ungrazed grassland grow tall and rank.
Due to its dependence on water, any extension of ecological range into drier habitats stops short of the point where there is no more access to moist green growth, or adequate water. Kobs are able to congregate and move from one resource to another. These movements follow seasonal changes in pasture. In areas with extensive flooding, travelings can involve many hundreds of km. Daily treks to water in the dry season may require a walk of 10 km or more. The more heavily grazed grasses in kob concentration areas have been documented as two Hyparrhenia species, Brachiaria brizantha, Setaria gayanus, Chloris gayana, Echinochloa and Digitaria. Bitter, aromatic species such as Cymbopogon are avoided.
Kobs have few strong social bonds, however females live in herds of they can reach the thousands. They tend to be more mobile and more social then territorial males which remain attached to their static territories as long as possible. It is the females that lend the daily movements to water regardless of the length of term or the scale. Individuals learn their routines from their mothers. However, the higher the density of individuals the more females will take their cues from other females. Males follow the females and may be an integral part of their herds. All-males herds that number up to several hundred individuals may associate with females during the dry season marches.
The social and reproductive organization of kobs can vary. At average or low population densities, males establish conventional territories that are spaced at least 100-200 m apart. Adult males try to establish their territories in the best habitat available which are inhabited by herds of females and their young. These herds are loosely structured and have open, changing composition and size as the animals move about their range searching for greener pastures. Non-territorial males, particularly young males, live in bachelor herds and are segregated from the females by the territorial males. On floodplains, where kobs live in high population densities, around two thirds of the territorial males defend conventional territories while the rest live in clustered territories known as leks. These clusters may be no larger than a single conventional territory. Lek clusters are located on short grass and bare ground and are surrounded by taller grassland. As such, these territories have litter to no value other than the males that reside in them. 8-9 of every 10 females visit leks to mate which makes it worth it for males to forego space and food for greater reproductive success. Females and bachelor males live in large herds of up to 2000 and circulate around a lek. Where are in the middle of the best pastureland and are near waterholes and well-traveled routes.
Aggression between territorial Ugandan kobs (K. k. thomasi) tend to be ritualized and rarely include actual fighting, whether in conventional territories or leks. If a neighbor enters his territory, perhaps to follow a departing female, a males will walk firmly towards the intruder in the erect posture which is usually enough to turn him back. this posture is also displayed when males encounter each other at a common boundry in the lek clusters. Fights are more frequent among white-eared males on leks., which have a restricted mating causing more intense reproductive competition. Among Ugandan kobs, severe and even fatal fights do occur, usually when a male tries to take over a territory. Fights usually involve the combatants clashing, pressing and twisting each other with their horns head on. However a neighbor may launch a damaging attack from the rear or side. In lek clusters, the most dominant males occupy the center. There are at 3-4 and at most 6-7 males in a lek cluster whose territories converge and monopolize copulations with estrous females. Replacement of males in leks are common with competitions so fierce that few males are able to hold central positions for a week and many last for only a day or two. This is an part become males most leave their territories to feed and drink. Centrally located males reduce the chances of being replaced by leaving to feed during tranquilities in mating, yet they are not able to make up for the energetic cost in maintaining a territory and must withdraw from their position. However, a male can recuperate after a week or two and try to take back his position. At every kob lek cluster, there is always a group of kobs trained to take or retake a territory. With conventional territories, replacement of the resident males are less common and these males are able to hold their places for at least a year or two.
Females begin to ovulate at 13-14 months and come into estrous every 20-26 days until they are inseminated. Courtship by males differs between males of conventional territories and lek territories. Males of conventional territories will try to prevent females from leaving and will chase and herd them. Lek males are unable to keep females from escaping, although they try. Kob courtship may last as little as 2-3 minutes and copulation may only last 1-2 seconds.At leks, a females may copulative up to 20 times by one or more of the central males. The gestation period lasts around 8 months and after calving, ovulation resumes 21-64 days later in perennial breeders. For their first month, calves lie concealed in high grass. Mothers and their calves use their noses to indentify one another. When they pass the hiding stage, calves join crèches and rarely go into tall grass. They rest together in available shades. When they are 3-4 months old, the young join the females herds and associate with their mothers until they are weaned at 6-7 months. When they mature, males join bachelors groups.
Hunting as well as loss of habitat to the expansion of settlements, agricultural development and livestock are major causes of population reduction. For example, the Uganda Kob formerly occurred in south-western Kenya and north-western Tanzania in grasslands alongside Lake Victoria, but was exterminated by the spread of settlement and agricultural development. Protected areas important for the survival of Buffon’s Kob, include: Niokolo-Koba in Senegal, Comoe in Côte d’Ivoire, Arly-Singou in Burkina Faso, Mole and Bui in Ghana, Pendjari in Benin, Waza and Benoué and Faro National Parks of the North Province of Cameroon, Zakouma in Chad, and Manovo-Gounda-St. Floris and Sangba in the Central African Republic.
^ a b c d IUCN SSC Antelope Specialist Group (2008). Kobus kob. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 10 May 2008.
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