The Biology, Husbandry and Conservation Scimitar-horned Oryx ...

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Wild Diet
TANIA GILBERT
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Part 1: Biology & Conservation
Scimitar-horned oryx are primarily grazers. However, as an arid land specialist, the species
demonstrates a flexible foraging strategy (Newby, 1975b; Wakefield, 1996a), exploiting a
range of additional plant materials including browse, seedpods of legumes, bulbs, tubers, and
succulents depending on season and availability (table 1.)(Macdonald, 2001; Kingdon, 1997;
Dolan, 1966). Hence, previous authors describe the importance of these different food plants
throughout the course of the year (Newby, 1975b; Devillers & Devillers-Terschuren, 2003).
Information on the diet of wild scimitar-horned oryx is available from observations from
Chad (Gillet, 1966a, 1966b; Newby, 1975b) prior to the species’ disappearance in the wild.
More recently, this has been supplemented with knowledge gained from the reintroduction of
scimitar-horned oryx to protected areas in Tunisia (Bertram, 1988; Gordon, 1991; Wacher,
1986b; Davey, 1999; di Crocio, 2003).
There are three distinct seasons within the natural range of the scimitar-horned oryx: the rainy
season; a cold, drier season; and, a hot dry season. The rainy season lasts from July to
September in the Sahelian range (Devillers & Devillers-Terschuren, 2003), but begins in
September in the northern Sahara fringe countries (E. Flach & S. Wakefield pers. comm.).
During this period, scimitar-horned oryx in the Sahel fed on temporary pastures formed by the
emergence of annuals and the green shoots of shrubs such as Indigofera sp. and Cordia
sinensis. Tuft grasses including Cymbopogon schoenanthus provided grazing immediately
after the rains, but oryx abandoned this species and the browses in favour of more palatable
grasses such as Cenchrus biflora, Panicum laetum and Dactyloctenium aegyptium as soon as
they became available (Newby, 1975b). Scimitar-horned oryx migrated northwards following
the rains and the formation of these temporary pastures (Gillet, 1965; Newby, 1974).
Many plants remain green and thus provided continued grazing for oryx over the subsequent
colder months between November to February. At the end of the cold season and the
beginning of the hot season, scimitar-horned oryx ate large amounts the newly fallen Acacia
seedpods of Acacia raddiana (Newby, 1975b). However, by the hot dry season from March to
June, scimitar-horned oryx became reliant on perennial grasses, notably Panicum turgidum
and Aristida sp., and browse species including Leptadenia sp., Cassia italica and Cornulaca
monacantha also formed an important part of the diet (Newby, 1975b; Devillers & Devillers-
Terschuren, 2003).
In areas with low, sporadic rainfall and high rates of evaporation, the environment may be
waterless for ten months of the year, but scimitar-horned oryx are perfectly adapted to cope
with these conditions (Bremen & de Wit, 1983; Newby, 1981a; Davey, 1999; Dolan, 1966).
The species can cope without free water for several months at a time, and it is reasonable to
assume that they do not drink from the end of the rainy season until the first rains fall, a
period of at least eight to ten months (Newby, 1975b, 1978a, 1978b; Anon, 1987a). However,
when free water is available, the oryx will take considerable risks to get it and will gorge
themselves, making it difficult for them to travel quickly over any distance (Newby, 1975b).