The Scimitar-horned Oryx (Oryx dammah) is one of two oryx species that went extinct in the wild (the other being the Arabian Oryx, Oryx leucoryx). The Scimitar-horned Oryx--both sexes of which have long, slender, hollow horns that are annulated (i.e. with ring-like divisions) for the basal third and curve over the back--used to be found on the southern and northern edges of the Sahara Desert. They did not inhabit the desert interior, as does the Addax (Addax nasomaculatus). The former range of the Scimitar-horned Oryx, which encompassed over 4 million square km, experiences prolonged droughts, the most recent of which extended from the 1960s to the early 1990s! The ongoing southward spread of the Sahara Desert likely contributed to the decline of this species. When sedentary, herds consisted of 10 to 30 or even 100 individuals. During migration, groups of 1000 or more would aggregate (an aggregation of 10,000 was reported from Chad in 1936). It is estimated the the wild population of Scimitar-horned Oryx once numbered around a million individuals. In addition to the expansion of the Sahara, the main causes of extinction were human population growth, motorized access to the desert, overhunting, and increased use of key habitats by livestock. The last known wild individuals were in Chad and Niger in the 1980s. Fortunately, captive populations were established beginning in the 1960s (around 4,000 captive animals are in the United Arab Emirates in a private collection and around 2,000 on private ranches in Texas, U.S.A.), so re-establishing wild Scimitar-horned Oryx populations is a possibility that is being actively pursued.
