Oryx leucoryx (Pallas, 1777)

Don E. Wilson & Russell A. Mittermeier, 2011, Bovidae, Handbook of the Mammals of the World – Volume 2 Hoofed Mammals, Barcelona: Lynx Edicions, pp. 444-779 : 647-648

143.

Arabian Oryx

Oryx leucoryx

French: Oryx d'Arabie / German: Arabische Oryx / Spanish: Oryx de Arabia

Other common names: White Oryx

Taxonomy. Antilope leucoryx Pallas, 1777 ,

Arabia.

Although oryxes from northern and southern Arabia have been described as different subspecies, no morphologic or genetic differences have been detected, and they are remarkably uniform in coloration. This species is considered monotypic here.

Distribution. Extinct in the wild by 1972, free-ranging Arabian Oryxes have been reestablished in Israel, WC Oman, and SW Saudi Arabia.

Descriptive notes. Head—body 153-235 cm, tail 45-60 cm, shoulder height 81-102 cm; weight 65-75 kg (males) and 54-70 kg (females). The Arabian Oryx is mostly whitish, but adults vary from cream to gray to brown, with brown and black markings. The bushytail is dark on the end. The lower limbs of adults are chocolate-brown to black, with white patches just above the hooves. Dark markings also occur on the face; a dark line runs down the jaw, connecting to small, triangular patches below the ears, which are connected to a bar through the eyes; a dark upwardly pointing triangle occurs on the nose below the eyes; and a black patch occurs on the forehead between the horns. Young oryxes only have tail and knee markings and are generally various shades of brown. The neck has a sparse mane. Both sexes have long slender horns of 60-150 cm that are less thick at the base (8-9 cm) than on other oryxes. Horns point upward and slightly back, away from the eyes, and are very straight. Female horns are slightly thinner and longer than male horns. The number of horn rings on the Arabian Oryx is 27-34, intermediate between the Scimitar-horned Oryx (O. dammah ) and the other oryx species. The skull and teeth of the Arabian Oryx are much smaller than other oryx species. Diploid chromosome number is 57-58; they are polymorphic for a very rare centric fusion between chromosomes 18 and 19. Dental formulais10/3,C0/1, P 3/3, M 3/3 (x2) = 32. Tooth eruption patterns permit aging of Arabian Oryxes in nine age classes up to 3-5 years, when all permanent teeth are present.

Habitat. The Arabian Oryx can inhabit several desert habitat types, such as stony plains, wadis, and sand dunes. Before extinction in the wild, they were generally found in arid plains and deserts but also in thicker brush and on rockyhillsides. They are able to exist in areas with low humidity, low rainfall, high, sandy winds, and high ambient temperatures over 45°C in summer, and can withstand droughts of 4-6 months. They also can inhabit flat limestone areas in Jiddat al Harasis that have shallow alkaline soils and rocky ridges and harsh diurnal temperature changes throughout the year. Vegetation consists of scattered grasses, shrubs, and small trees and shrubs such as Acacia. Rainfall is unpredictable and sporadic, averaging less than 50 mm /year.

Food and Feeding. Herbivorous, mixed feeder but primarily a grazer. The Arabian Oryx can survive on poor-quality forage and eats various grasses, herbs, roots, and tubers. The main diet includes ephemerals, forbs, coarse grasses such as Stipagrostis, and dwarf shrubs such as Zygophyllum. They will drink water from ephemeral streams and waterholes, but such sources are rare and dispersed. When standing water is not available, Arabian Oryxes can go for indefinite periods without it, obtaining all they need from their food (e.g. succulent bulbs and melons). They can maintain an adequate water balance at 31°C if their diet contains at least 35% water. The Arabian Oryx also obtains moisture from condensation on rock surfaces and vegetation after thick fogs. It has a very low mass-specific water-influx rate compared to other bovids.

Breeding. Female Arabian Oryxes are polyestrous, and males follow them throughout the year, courting and attempting to breed. There is no set reproductive season, and a female can produce a calf once a year during any month. Captive females initially give birth at 2-5-3-5 years of age to a single offspring. Gestation is about 240 days. Young are weaned by 4-5 months. A postpartum female is consorted by an adult dominant male during the calf’s hiding phase, which occurs in its first month. Neonates spend most of the hiding period lying motionless, with short periods of activity. When the calf rises to approach its mother, the male often positions itself a few meters behind it, growling and directing it straight to its mother. The attending male is usually the dominant herd male even if the calf was fathered by another male. Captive Arabian Oryxes have lived over 20 years;little is known about longevity in the wild.

Activity patterns. Activities of the Arabian Oryx are concentrated in the morning and evening. During the heat of the day, groups seek shade to minimize heat gain and to rest/ruminate in. To provide more protection from the heat, they dig depressions in the ground, bedding in the cooler sand beneath. Shrubs and trees provide protection from high winds. Time spent in the shade depends on the ambient temperature; on very hot days, Arabian Oryxes spend seven hours or more in the shade, within 1-2 m of one another. To compensate for this inactivity, they forage longer at night. During colder seasons, the Arabian Oryx will bask in the sun, feed throughout the day, and become inactive at night to prevent heat loss.

Movements, Home range and Social organization. The Arabian Oryx is gregarious; typical group size is ten individuals, but herds as large as 100 individuals have been noted. Groups usually contain one adult dominant male, several adult females, and their young; group size varies with weather and forage conditions. Before their extinction in the wild, total annual home ranges were probably several thousand square kilometers. During a reintroduction effort in the United Arab Emirates in 2007, radio-collared Arabian Oryxes initially wandered over a large area (some individuals more than 1000 km?), and then settled into a pattern of occupying smaller seasonal ranges, about 5 km? during the hottest months of the year and about 100 km ” during milder months. Their movements are highly dependent on rainfall, which they can sense from considerable distances. Because desert rainfall patterns are unpredictable, herds travel in no set pattern. After grazing in one area, the Arabian Oryx typically does not return to the same area for several months. As the size of a population increases, large groups may break up into several smaller groups. These groups develop their own home ranges, which often overlap. Independent movements occur within herds and vary depending on age and gender. Subordinate adult males often leave the herd, looking for new territories in which to establish their own herds. When calves are young, they follow their mothers closely while grazing. With maturity, mother—calf relationships become looser. While the herd grazes, females without young calves lead the way; females with young calves trail behind, followed by the dominant male, and lastly subordinate males. Average distance between individuals is 5-10 m when feeding in a concentrated food patch, but a group will spread out over larger areas when food resources are widely scattered. A herd travels close together and in single file when making long-distance movements; the dominant male brings up the rear. Herd cohesion is maintained by visual contact during the day and soft mooing at night.

Status and Conservation. CITES Appendix I. Classified as Endangered on The IUCN Red List, but may meet the criteria to be down-listed to Vulnerable in 2011. Formerly present throughout the Arabian Peninsula, extending north to Israel, Jordan, Kuwait, Iraq, Syria, and Sinai and including the Dahana, the Rub’ al-Khali, and Great Nafud deserts. The Arabian Oryx existed in the wild until 1972, when poaching and overhunting led to the loss of the last wild individuals at Jiddat al Harasis, Oman. Because of concern about the imminent extinction of the Arabian Oryx , captive breeding programs were started in several Arabian countries as early as the 1950s. In 1962, wild Arabian Oryxes were brought to the Phoenix Zoo in Arizona, USA,to serve as the foundation for subsequent international breeding and reintroduction efforts. Offspring from this pair, and from a separate breeding group with new founders at the Los Angeles Z00, were sent to other breeding programs around the world, including the Middle East. Captive-bred Arabian Oryxes were sent to Oman for the first reintroduction effort in 1982. Subsequently, Arabian Oryxes have also been repatriated in two reserves in Saudi Arabia and three locations in Israel. A reintroduction effort started in 2007 in the United Arab Emirates. Future reintroductions are planned for Jordan and possibly Yemen. There are 6000-7000 Arabian Oryxes in captivity throughout the world, most of them on the Arabian Peninsula and some in large enclosures, receiving various amounts of supplemental food and care, in Syria, Bahrain, Qatar, and the United Arab Emirates. Only about 250 mature individuals exist among the reintroduced free-ranging populations.

Bibliography. Ancrenaz & Delhomme (1997), Ansell (1972), El Algamy et al. (2008), Gilad et al. (2007), Gerth et al. (1991), IUCN/SSC Antelope Specialist Group (2008a0), Marshall et al. (1999), Mésochina et al. (2003), Molcanova & Wacher (2008), Ostrowski, Bedin et al. (1998), Ostrowski, Williams & Ismael (2003), Ostrowski, Williams, Mesochina & Sauerwein (2006), Seddon & Ismail (2002), Stanley Price (1989), Tear et al. (1997), Treydte et al. (2001), VlIé (1996), Weigl (2005).

Figures

138. Beisa Oryx (Oryx beisa), 139. Galla Oryx (Oryx gallarum), 140. Fringe-eared Oryx (Oryx callotis), 141. Gemsbok (Oryx gazella), 142. Scimitar-horned Oryx (Oryx dammah), 143. Arabian Oryx (Oryx leucoryx)

Distribution. Extinct in the wild by 1972, free-ranging Arabian Oryxes have been reestablished in Israel , WC Oman , and SW Saudi Arabia .