Contents - Marwell Zoo

Reproduction
Scimitar-horned oryx have a gestation period of between 242 to 300 days (approximately
eight and a half months) and most of the time a single calf in born (Dolan, 1966; Dittrich,
1972; Anon, 1987; Newby, 1988). If a male is present during the female’s post-partum
oestrus, it is possible for females to fall pregnant again immediately. Therefore under
favourable conditions females can have a calf every eight and a half to nine months
(Nishiki, 1992; Wakefield & Engel, 2004). As such it may be necessary to separate the
sexes at certain times of the year to control breeding.
Calves are capable of following their mothers a few hours after birth (Dolan, 1966), but in
the wild lay hidden in vegetation for the first two weeks of their life (IUCN, 1987; Gill &
Cave-Browne, 1988). After two weeks they are crèched with calves of a similar age and
are weaned at four to ten months (Newby, 1974; 1984; Mayor, 1984; Gill & Cave-Brown,
1988). In captivity, the calves will be crèched in a suitable location in the enclosure.
Females reach sexual maturity between 11 and 35 months, and males between 10 and 30
months (Dittrich, 1970, 1972; Dolan, 1976; Gill & Cave-Browne, 1988; Puschmann, 1989;
Nishiki, 1992; Volf, 1994; Engel, 2004b).
Social structure
Before their extinction in the wild, scimitar-horned typically formed herds of between 15
and 40 animals, but at certain times of the year, during their seasonal migrations or in areas
of fresh pasture, aggregations of thousands could be seen (Dolan, 1966; Newby, 1978a,
1988; Barzdo, 1982, Devillers & Devillers-Terschuren, 2004). Some authors have
suggested that herds were led by an adult bull (Dolan, 1966; Kranz & Ralls, 1979), but
Newby (1974) reported that an adult female lead the group. Old males expelled from the
herds and tended to be solitary (Dolan, 1966), although it is possible that bachelor herds
were formed (Engel, 2004c).
Scimitar-horned oryx have a well-defined linear dominance hierarchy (Pfeifer, 1985;
Engel, 2004d) which is evident in zoological institutions and at release sites in Tunisia
(Wacher, 1986; Gordon, 1987; Molcanova, 2004). However, this may be disrupted if an
individual is removed from the herd for some period of time and reintroduced at a later
date (Engel, 2004d).
The social organisation of captive scimitar-horned oryx is dictated either by the institutions
in which they are held or the requirements of the regional coordinated captive breeding
programme. European zoos hold all-female herds, bachelor herds, harem groups with
mixed sex calves, or mixed sex herds with castrated males. The majority of the herds are
all-female or harem groups and this has resulted in a surplus male problem which needs
addressing.
Ecology
Historically scimitar-horned oryx could be found on the arid grassy steppe that lies
between the Sahel and the desert vegetation zones to the south of the Sahara (Newby,
1978a), and the Mediterraneo-Saharan transition zone to the north of the Sahara (Devillers
& Devillers-Terschuren, 2003). These areas are characterised by scrub vegetation,
scattered trees, rolling dunes and wooded inter-dunal depressions receiving an annual
rainfall of 100 to 400mm (Dolan, 1966; Newby, 1978b, 1980, 1988; Anon, 1987). The rain
falls in just one season, to the south of the Sahara this is from June to September (Anon,
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