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Animal Info - Scimitar-horned Oryx

(Other Names: 弯角剑羚, 弯角大羚羊, 彎角羚, シロオリックス, Algazelle, Antilope Oryx, Begar al Ouach, Orix de Cimitarra, Oryx Algazelle, Oryx Blanc, Oryx de Libye, Sahara Oryx, Säbelantilope, Scimitar Oryx, Wach)

Oryx dammah (O. tao)

Status: Extinct in the Wild


Contents

1. Profile (Picture)
2. Tidbits
3. Status and Trends (IUCN Status, Countries Where Currently Found, Population Estimates, History of Distribution, Threats and Reasons for Decline)
4. Data on Biology and Ecology (Weight, Habitat, Age to Maturity, Gestation Period, Birth Season, Birth Rate, Maximum Age, Diet, Behavior, Social Organization, Density and Range, Mortality and Survival)
5. References


Profile

Pictures: Scimitar-horned Oryx #1 (Huffman 2004); Scimitar-horned Oryx #2 (62 Kb JPEG) (AZA Antelope TAG) 

The scimitar-horned oryx, named for its scimitar-shaped horns, weighs up to 220 kg (480 lb). The scimitar-horned oryx inhabits the sub-desert lands - the transition zones between true desert (Sahara) and the Sahel, with a rainfall of between 75 and 150 mm (3 - 6"). It is found in rolling dunes, grassy steppes and wooded inter-dunal depressions. It very rarely penetrates either true desert or true Sahel country. The scimitar-horned oryx selectively feeds on a variety of foods - primarily grasses, but also legumes and leaves and the fruit of trees and shrubs.  It is well adapted to arid lands, being able to go for 9 - 10 months without drinking water by utilizing the moisture in the vegetation it eats.

The scimitar-horned oryx is a gregarious, living in groups with a wide range of sizes. In the past, at certain times of the year, in areas of fresh pasture or surface water after rainfall, or during the wet season migrations, herds numbered up to 1000 or more. Herds of scimitar-horned oryx migrated north into the Sahara during the wet season and returned south at the beginning of the dry season.

The scimitar-horned oryx was formerly distributed from Mauritania in the west to the Red Sea in the east, but it declined drastically, apparently to extinction in the wild. Overhunting is the major cause of the decline, especially after motorized hunting with modern firearms began. Hunting has been carried out by nomads, oil surveyors, and military personnel, for meat, hides and sport. In addition, its habitat became increasingly drier and less suitable, due to long-term climate change as well as to overgrazing by livestock and man's destruction of tree cover. Furthermore, the increasing presence of livestock drove the oryx away from the pastures where it formerly obtained both food and water.


Tidbits

*** In the early 1970's, the scimitar-horned oryx, together with the addax, were considered the most endangered of the African antelopes (Curry-Lindahl 1972). The scimitar-horned oryx has proved to be even more vulnerable to human disturbance than the addax, because of its inability to penetrate the harsh desert except when scarce rain has fallen to promote plant growth. 

*** The scimitar-horned oryx has a number of physiological adaptations to conserve body water that help it survive in its desert habitat. For example, its kidneys are very efficient at minimizing the loss of water in urine, and it sweats only when its body temperature exceeds 46 deg C (116 deg F). 

*** In 1986, a breeding herd of 10 juvenile scimitar-horned oryx (5 males and 5 females), were released into the Bou Hedma National Park in Tunisia. These oryx reproduced successfully and by 1997, the first ten oryx had produced a herd of 84 animals. (Intl. Found. Cons. Wildl. 2004)


Status and Trends

IUCN Status:

  • 1960's - 1970's: Vulnerable
  • 1980's - 1994: Endangered
  • 1996: Critically Endangered (Criteria: A1c, C1+2a)
  • 2000 - 2004: Extinct in the Wild (IUCN 2004)

Countries Where the Scimitar-horned Oryx Is Currently Found:

2004: Occurs in Israel (introduced populations) and Tunisia (re-introduced populations).  May occur in Niger(IUCN 2004)

Population Estimates:

[Note: Figures given are for wild populations only.]

History of Distribution:

During the Middle Ages the scimitar-horned oryx was probably the most numerous large mammal of the semideserts just south of the Sahara. It was distributed from Mauritania in the west to the Red Sea in the east, along the interface between true desert and less arid Sahelian or Mediterranean habitats under an annual rainfall of between 75 and 150 mm (3 - 6"). Even as late as the 1920's and 30's it was considered common over much of its range from the Atlantic to the Nile. By the 1950's its range was fragmented, although substantial numbers survived in some areas. By the late 1970's it only survived in scattered populations. By the mid-1980's it was said to be on the brink of extinction. By 2000, it was thought to be extinct in the wild, although there was a recent unsubstantiated sighting of four animals in northern Niger (IUCN 2004).

A summary chronology of extinctions of the scimitar-horned oryx in the wild: Tunisia (1910), Morocco (1973), Egypt (1975), Algeria (1987), Mali (1990), Niger (1990), Sudan (?), Libya (?), Chad (2000) (Mallon & Kingswood 2001, IUCN 2004)

Distribution Map (15 Kb GIF) (African Mammals Databank 2004)

Threats and Reasons for Decline:

The original decline of the scimitar-horned oryx started with climatic changes that led to the drying out of the Sahara. As the desert expanded to north and to south, the scimitar-horned oryx was pushed northward and southward, and desertification divided it into two isolated populations. The northern group probably was never as common as the southern group. 

The decline of the southern group worsened beginning with the arrival of Europeans in western and westcentral Africa in the latter part of the 19th century and the installation of numerous military posts in the arid regions. As firearms and horses increased, and then motorized vehicles were introduced, hunting began to take a major toll. The hunting was carried out by nomads for meat and hides for domestic consumption and trade, and by oil surveyors and troops. Not only were animals shot from motorized vehicles, sometimes with automatic weapons, but many of the slow-running desert animals died of heat exhaustion, calves were abandoned in the chase and unborn young aborted. During World War II, military operations probably led to considerable additional hunting to feed the armies. Finally, the civil war which began in Chad in the 1960's had a serious effect.

In addition to the major impact of overhunting, the increasing presence of livestock, stimulated by deep wells for watering cattle on the edge of the Sahel, drove the oryx away from the pastures where it formerly obtained both food and water.


Data on Biology and Ecology

Weight:

The scimitar-horned oryx weighs up to 220 kg (480 lb).

Habitat:

The scimitar-horned oryx inhabits the sub-desert lands - the transition zones between true desert (Sahara) and the Sahel, with a rainfall of between 75 and 150 mm (3 - 6"). It is found in rolling dunes, grassy steppes and wooded inter-dunal depressions. It very rarely penetrates either true desert or true Sahel country (Newby 1980).

The scimitar-horned oryx occurs in the Mediterranean Basin Biodiversity Hotspot (Cons. Intl.).

Age to Maturity:

Young are sexually mature by 2 years of age (Burnie & Wilson 2001).

Gestation Period:

8 - 8.5 months.

Birth Season:

Births may occur throughout the year but with peaks occurring during the late cold/early hot season (February - April) and the late rainy/early cold season (September - November) (East 1990).

Birth Rate:

A female scimitar-horned oryx has 1 young per birth.

Early Development:

The mother leaves the herd to calve but returns within hours. Young are weaned by 14 weeks (Burnie & Wilson 2001).

Maximum Age:

Captive animals have lived for 17 years (Kingdon 1997).

Diet:

The scimitar-horned oryx selectively feeds on a variety of foods - primarily grasses, but also legumes and leaves and the fruit of trees and shrubs (Mallon & Kingswood 2001).

Like many arid-area adapted mammals, scimitar-horned oryx are able to survive without drinking water for 9 - 10 mouths, drawing sufficient moisture from their plant food (Newby 1980).

Behavior:

In the Sahelian range of the scimitar-horned oryx, seasonal migrations over significant distances, up to several hundred km (1-200 miles), have been recorded. During the hot season, from March to May, the oryx are found in the southern part of their range. At the beginning of the rains, that appear in the south of the Sahel at the end of May or the beginning of June, they move further south, to the sub-Sahelian wooded steppes. At the end of June or in July, they perform rapid, massive migrations towards the north of their range, where the rains have started, taking advantage of the pastures to the extent that competition with domestic herds permits. In August they reach the northernmost latitudes, between 16 and 17 deg N latitude. In October and November, the larger herds disperse for the cold season. They return in March towards the summer quarters. This cycle varies as a function of variations in the annual rainfall. (Beudels-Jamar et al. 1998)

The scimitar-horned oryx is primarily crepuscular, although it also feeds during moonlit nights.  During the day it rests in the shade if available. (Mallon & Kingswood 2001)

Social Organization:

Scimitar-horned oryx are gregarious. They are found in herds whose size constantly changes, depending on the size of the patches of vegetation they are feeding on. New herds collect and disperse as ephemeral vegetation comes and goes in response to irregular rainfall. In the past the groups could be quite large - a single herd of 10,000 oryx was sighted in 1936. As oryx populations shrank, so did the herd size.  

Density and Range:

One estimate of typical density suggested one scimitar-horned oryx for every 40 sq km (15 sq mi) of desert habitat (Kingdon 1997).

Mortality and Survival:

Observations in Chad showed that the scimitar-horned oryx had an annual birth rate of approximately 12 - 15% of the total population, and the number of surviving juveniles may have been as high as 10 - 14% annually (Newby 1980).


References

African Mammals Databank 2004, Arkive, AZA 1994a, AZA Antelope TAG, Bassett 1975, Beudels-Jamar et al. 1998, Burnie & Wilson 2001, Burton & Pearson 1987, Cons. Intl., Curry-Lindahl 1972, East 1990, Fossil Rim Wildlife Center, Huffman 1999f, Intl. Found. Cons. Wildl. 2004, Huffman 2004, IUCN 1969, IUCN 1994, IUCN 1996, IUCN 2000, IUCN 2003a, IUCN 2004, Kingdon 1997, Macdonald 1984, Mallon & Kingswood 2001, Newby 1978, Newby 1980, Nowak & Paradiso 1983, Oryx 1970, Oryx 1982c, Oryx 1984, Oryx 1986g, Oryx 1987, Oryx 1989e, Stuart & Stuart 1996


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