Scimitar oryx

Appearance

The scimitar oryx is a spiral-horned antelope that stands just over 1 m at the shoulder. The males weigh 140–210 kg and the females 91–140 kg . The body measures 140–240 cm from the head to the base of the tail. The tail is 45–60 cm long and ends with a tuft. Males are larger than females.

Its coat is white with a red-brown chest and black markings on the forehead and down the length of the nose. The coat reflects the sun's rays, while the black portions and the tip of the tongue provide protection against sunburn. The white coat helps to reflect the heat of the desert. Calves are born with yellow coats and lack distinguishing marks, which appear later in life. Their pelage changes to adult coloration at 3–12 months old.

Both sexes have horns, but those of the females are more slender. The horns are long, thin, and symmetrical; they curve backwards and can reach 1.0 to 1.2 m on both the males and the females. The horns are so thin that they can break easily. The female has four nipples. The large, spreading hooves are well adapted to allow these antelopes to walk on the sand of their dry habitats. A scimitar oryx can live as long as 20 years. At Smithsonian National Zoo, a female oryx died at 21, an exceptional age since females generally have a lifespan of about 15 years.

Naming

The scimitar oryx is a member of the genus ''Oryx'' and family Bovidae. The German naturalist Lorenz Oken first described it in 1816, naming it ''Oryx algazel''. The nomenclature has undergone various changes since then, with the introduction of names like ''Oryx tao'', ''O. leucoryx'', ''O. damma'', ''O. dammah'', ''O. bezoarticus'' and ''O. ensicornis''. In 1826, Philipp Jakob Cretzschmar used the name ''Oryx ammah'' for the species. A year later, the name ''Orys leucoryx'' came into use, but as this was a synonym of the Arabian oryx , it was abandoned, and ''Oryx algazel'' was accepted once more. Over a hundred years later, in 1951, Sir John Ellerman and Terence Morrison-Scott realized the invalidity of the name ''Oryx algazel''. Finally, in January 1956, the International Trust for Zoological Nomenclature accepted ''Oryx dammah'' as the scientific name. There have been no more changes since then, though many papers published after 1956 created confusion by using names like ''O. gazella tao''....hieroglyph snipped...

Its scientific name, ''Oryx dammah'', is derived from: Ancient Greek , meaning a gazelle or antelope ; Latin ''damma'' ; and Arabic ''dammar'' . The scimitar oryx is named for its horns, which resemble scimitars. Its common name in English is "scimitar-horned oryx", or simply "scimitar oryx".

Distribution

The scimitar oryx once inhabited grassy steppes, semideserts and deserts in a narrow strip of central north Africa . It was widespread on the fringes of the Sahara, mainly in the subdesert Great Steppe, the grassy zone between the real desert and the Sahel, an area characterized by an annual rainfall of 75–150 mm . In 1936, a single herd of 10,000 oryx was seen in the steppe area of Chad. By the mid-1970s, Chad was home to more than 95% of the world population of this species.

Status

The scimitar oryx was hunted almost to extinction for its horns. Its population decline began as a result of major climatic changes that caused the Sahara to become dry. The northern population was already almost lost before the 20th century. The decline of the southern population accelerated as Europeans began to settle the area and hunt them for meat, hides and horn trophies. World War II and the Civil War in Chad that started in the 1960s are thought to have caused heavy decreases of the species through an increase in hunting for food. Roadkill, nomadic settlements near waterholes and firearms for easy hunting have also reduced numbers.

The IUCN lists the scimitar oryx as regionally extinct in Algeria, Burkina Faso, Chad, Egypt, Libya, Mali, Mauritania, Morocco, Niger, Nigeria, Senegal, Sudan, Tunisia and Western Sahara, and has assessed it as extinct in the wild since 2000. Reports of sightings in Chad and Niger remain unsubstantiated, despite extensive surveys carried out throughout Chad and Niger from 2001 to 2004 in an effort to detect antelopes in the Sahel and the Sahara. At least until 1985, 500 oryx were estimated to be surviving in Chad and Niger, but by 1988, only a few individuals survived in the wild.

There is now a global captive breeding program for the scimitar oryx. In 2005, at least 1,550 captives were managed as part of breeding programs, and in 2008, more than 4,000 were believed to be held in private collections in the United Arab Emirates. Reintroduction plans involve fenced-in herds in Bou Hedma National Park , Sidi Toui National Park and Oued Dekouk National Park in Tunisia; Souss-Massa National Park in Morocco; and Ferlo Faunal Reserve and Guembuel Wildlife Reserve in Senegal.

Behavior

The scimitar oryx was a very sociable animal and traveled in herds of between two and forty individuals, generally, led by a dominant bull. This species once gathered in groups of several thousand for migration. During the wet season, they migrated north into the Sahara. Scimitar oryx are diurnal. In the cool early mornings and evenings, they rest under trees and shrubs, or if neither are available, they dig depressions in the soil with their hooves and rest there. Males fight often, but not for long and not violently. Predators, such as lions, leopards, hyenas, cheetahs, golden jackals, vultures and Cape hunting dogs, mostly kill weak and young oryx....hieroglyph snipped...

The play activity of eight calves in captivity was observed in a 1983 study. Male calves played for longer than females calves did. Mixed sex play was usual; selection of partners depended on age, but not on sex or genetic relatedness. Results suggested that size dimorphism was an important factor responsible for sex differences in play.

Habitat

The scimitar oryx was a very sociable animal and traveled in herds of between two and forty individuals, generally, led by a dominant bull. This species once gathered in groups of several thousand for migration. During the wet season, they migrated north into the Sahara. Scimitar oryx are diurnal. In the cool early mornings and evenings, they rest under trees and shrubs, or if neither are available, they dig depressions in the soil with their hooves and rest there. Males fight often, but not for long and not violently. Predators, such as lions, leopards, hyenas, cheetahs, golden jackals, vultures and Cape hunting dogs, mostly kill weak and young oryx....hieroglyph snipped...

The play activity of eight calves in captivity was observed in a 1983 study. Male calves played for longer than females calves did. Mixed sex play was usual; selection of partners depended on age, but not on sex or genetic relatedness. Results suggested that size dimorphism was an important factor responsible for sex differences in play.The scimitar oryx once inhabited grassy steppes, semideserts and deserts in a narrow strip of central north Africa . It was widespread on the fringes of the Sahara, mainly in the subdesert Great Steppe, the grassy zone between the real desert and the Sahel, an area characterized by an annual rainfall of 75–150 mm . In 1936, a single herd of 10,000 oryx was seen in the steppe area of Chad. By the mid-1970s, Chad was home to more than 95% of the world population of this species.

Reproduction

Both males and females reach sexual maturity at 1.5 to 2 years of age. Births peak between March and October. Mating frequency is greater when environmental conditions are favorable. In zoos, males are sexually most active in autumn. The estrous cycle lasts roughly 24 days, and females experience an anovulatory period in spring. Periods between births are less than 332 days, showing that the scimitar oryx is polyestrous.

Courting is done by means of a mating circle: the male and female stand parallel to one another, facing in opposite directions, and then circle around each other until the female allows the male to mount from behind. If the female is not ready to mate, she runs away and circles in the reverse direction. Pregnant females leave the herd for a week, give birth to the calf and conceive again during their postpartum estrus; thus they can produce a calf a year. Gestation lasts about nine months, after which a single calf is born, weighing 20 to 33 pounds . Twin births are very rare - only 0.7% of the births observed in one study. Both mother and calf return to the main herd within hours of the birth. The female separates herself from the herd for a few hours while she nurses the calf. Weaning starts at 3.5 months, and the young become fully independent at around 14 weeks old.

Food

The habitat of scimitar oryx in the wild was steppe and desert, where they ate foliage, grass, herbs, shrubs, succulent plants, legumes, juicy roots, buds, and fruit. They can survive without water for nine to ten months because their kidneys prevent water loss from urination – an adaptation to desert habitats. They can get water from water-rich plants such as the wild melon and ''Indigofera oblongifolia'' and from the leafless twigs of ''Capparis decidua''. In the night or early morning, they often search for plants such as ''Indigofera viscosa'', which produce a hygroscopic secretion that fulfils water requirements. They eat tuft grasses such as ''Cymbopogon schoenanthus'' after it has rained, but they normally prefer more palatable grasses, such as ''Cenchrus biflora'', ''Panicum laetum'' and ''Dactyloctenium aegyptium''. When the dry season begins, they feed on the seedpods of ''Acacia raddiana'', and during the dry season, they rely on perennial grasses of genera such as ''Panicum'' and ''Aristida'', and browse plants such as ''Leptadenia'' species, ''Cassia italica'' and ''Cornulaca monacantha''.

Evolution

The scimitar oryx has 58 chromosomes. It has one pair of large submetacentric autosomes and 27 acrocentric autosomal pairs. The X and Y chromosomes are the largest and smallest acrocentrics. The first molecular study of this species observed genetic diversity among European, North American and some other captive groups. Divergence was found within the mitochondrial DNA haplotypes, and was estimated to have taken place between 2.1 and 2.7 million years ago. Population increases occurred approximately 1.2 and 0.5 million years ago.

In another study, intended to note genetic differences between ''Oryx'' species, karyotypes of ''Oryx'' species and subspecies – namely ''O. gazella'', ''O. b. beisa'', ''O. b. callotis'', ''O. dammah'' and ''O. leucoryx'' – were compared with the standard karyotype of ''Bos taurus''. The number of autosomes in all karyotypes was 58. The X and Y chromosomes were conserved in all five species.