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Damaliscus dorcas phillipsi- Blesbok
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Legal status
Categorised as "Open game" in KwaZulu-Natal, and not listed in the S A Red Data Book nor any
CITES appendices.
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Distribution and status
In former times blesbok occurred only on the plains of north-western and western
KwaZulu-Natal, as well as East Griqualand (du Plessis 1969, Skead 1987) - possibly in the same
areas in which black wildebeest occurred.
Blesbok became extinct in KwaZulu-Natal, probably during the first decade of the twentieth
century. During the past thirty years blesbok have been introduced, mainly from the Orange Free
State, to numerous properties in KwaZuku-Natal, many of them outside of the former range.
There are currently about 7000 blesbok in 140 separate populations. Twelve of these (about
1500 animals) are in protected areas, viz Vryheid, Chelmsford, Spioenkop, Moor Park, Kamberg, Queen
Elizabeth Park, Midmar, Himeville, Coleford, Highmoor, Mount Currie, and Vernon Crookes. On private
land Howard & Marchant (1984) reported increasing populations on 56 % of the properties on
which they occur, and stable populations on 44 %.
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Living requirements
Open grassland, on flat to gently undulating terrain, is the only favoured habitat (Rowe-Rowe
1983, 1988 a). Such areas occur in the grassland bioclimatic regions between 920 and 1900 m above
sea level, viz Mistbelt, Moist upland, Drier upland, Highland, and parts of Coast hinterland.
Blesbok are grazers which feed mainly on short grass (Rowe-Rowe 1982 a), preferring the young
growth following defoliation. Where defoliation has occurred they are selective for growth stage,
but in older grass they select palatable species (Marchant 1986). In ideal habitat, and in the
absence of competition from grazers of the same feeding class, blesbok can occur at densities of
1/4 ha (Marchant 1986, 1987). A realistic figure for a system in which other short-grass grazers
are present is 1/10 ha. Minimum recommended enclosure size is 100 ha.
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Social organisation
In large populations the social organisation is typical of Jarman's (1974) class D (Lynch
1974) : - Territorial males occur singly. Adult females, sub-adult females, and young form
harem-nursery herds of between 10 and 30 individuals, while sub-adult and non-territorial males
form separate herds. In small populations the territorial male and the harem-nursery herd remain
together throughout the year (Rowe-Rowe 1973 a). Territory size is 5 - 10 ha, and area of home
range depends on herd size.
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Population dynamics
Blesbok are seasonal breeders. The rut takes place during March and April. Calving reaches a
peak during November in KwaZulu-Natal (Rowe-Rowe & Bigalke 1972), following a gestation of 8
months (Mentis 1972). First parturition usually takes place at 3 years, but some females first
calve at 2 years. Longevity in the wild is 12 or 13 years, and females can be expected to produce
one calf per annum. In populations where selective shooting is not practised the male : female sex
ratio is in the region of 1 : 1,7 (Rowe-Rowe 1982 b). Marchant (1986) proposed an adult sex ratio
of 1 : 3 for maximum productivity on farms. In newly established herds the population should
increase by about 20 % per annum.
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Threats
There are no current threats to the future of blesbok in KwaZulu-Natal. Some of the small
populations on farms die out or remain static, mainly owing to lack of suitable habitat management
(Marchant 1987). Certain populations are also likely to be adversely affected by commercial
afforestation.
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Human importance
Blesbok are shot for sport, meat, and trophies: several hundred being shot per year. Many
animals are captured and sold, and the demand for live blesbok in KwaZulu-Natal has remained high.
Some farmers have had problems with cattle contracting ophthalmia from blesbok. On some
properties blesbok have been responsible for site-selective grazing and overgrazing. This problem
usually occurs when blesbok are overstocked, or veld is not managed to suit them.
THE UNGULATES OF NATAL
D T ROWE-ROWE
ISBN 1-874965-07-2
BLESBOK SPOOR
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