Addax nasomaculatus (Blainville, 1816)

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 : 642-643

137.

Addax

Addax nasomaculatus

French: Addax / German: Addax / Spanish: Adax

Taxonomy. Antilope nasomaculata de Blainville, 1816 ,

Senegambia.

The question of whether there could be differences between the eastern and western Saharan populations of this species has been raised several times, but there appears to be nothing to substantiate it. This species is considered monotypic here.

Distribution. Only confirmed existing population in Termit and Tin Toumma regions of EC Niger; however, there is a recent confirmed sighting from C Mauritania and sporadic records from E Air Mountains in Niger, the Equey region in W Chad, S Algeria, Libya, and the Mali / Mauritania border.

Descriptive notes. Head—body 120-130 cm, tail 25-35 cm, shoulder height 105-115 cm (males) and 95-110 cm (females), ear 17-20 cm, hindfoot 44-45 cm; weight 100 —125 kg (males) and 60-90 kg (females). The Addax is a rather heavily built antelope; its barrel shape reduces the surface-to-volume ratio, advantageous for thermoregulation. The muzzle is hairy except for a thin strip between and above nostrils. The terminal tail tuft is small. Hooves are wide, low, rounded anteriorly and posteriorly; lateral hooves are well developed. Foot glands present in all four feet; inguinal glands absent and, unlike the oryx , preorbital glands are absent, but the area is covered by a large tuft of hair. Both sexes have horns, but those of the male are longer (males, 70-85 cm, max. 109-2 cm; females, 55-80 cm). Horns are spirally twisted, with 2-5-3 loose turns in males and 1-5-2 in females, diverging from base; the tips generally point outward. Horns are ringed strongly at the base, but the rings become reduced along the length. Color pale gray-brown on nose, neck, and body, whitish on legs and haunches as well as on underparts; the tone becomes paler with age. The pelage of the Addaxis grayer in the winter, paler in the summer. The forehead is dark, sometimes blackish-brown; a white H-shaped band occurs across the nose,its lower edges extending almost to the Jaw line and its upper edges extending back above the eyes. There is a scruffy short mane around the neck. The diploid chromosome number is 58. Molars are hypsodont, and the dental formulais10/3,C0/1,P3/3,M 3/3 (x2) = 32.

Habitat. Deserts and semi-desert country, even going into sand dunes, to which it is well adapted, with its wide, spreading hooves.

Food and Feeding. Desert grasses, shrubs, and trees; capable of going for long periods without water. It has been found that dietary fluids are retained in the stomach for an average of 20 hours, and non-fluid particles for an average of 42 hours, longer than most other ruminants—an evident adaptation to the slow-fermenting grasses ofits diet and the need to conserve water. Addaxes do not require standing water, but they will drink if it is available.

Breeding. Addax courtship includes ritualized foreleg kicking called “laufschlag,” as with its close relatives. The bull rests his chin on the female’s croup as a prelude to mounting. The female responds by circling, her head low, like the Roan Antelope ( Hippotragus equinus ), the Southern Sable Antelope ( H. niger ), and oryx species. While mating, the male rears upright, firmly grasping the female's loins. Estrus lasts 24-48 hours, gestation is 257-270 days, and postpartum estrus occurs within 2-3 days. Females give birth to a single offspring, weighing about 5 kg, at any time during the year, with modest peaks in winter and spring. Females alternately stand and lie down during parturition. Neonates are hiders, rejoining the herd, but forming a créche with other calves, after about two weeks. The calves stand to suckle at first, and then, after about 15 weeks, kneel; they are weaned at 23-29 weeks. Maximum longevity was about 28 years for a captive female, but survival of both sexes is no doubtfar less in the wild.

Activity patterns. Addaxes are active in the morning and evening, lying in the shade of vegetation during the heat of the day. Because of their build, they move heavily and are not fast runners. Addaxes once moved north and south across the Sahara according to season. In cold or windy weather, they dig depressions in the sand in which theylie for protection. Oryxes and Addaxes amble, nodding their heads when walking fast. An addax walks with one foot behind the other, leaving a single line of tracks. It has a flat, ratherstiff-legged gallop.

Movements, Home range and Social organization. Apparently, the Addax is not territorial but lives in harems of a single male and several females and young. Group sizes are typically 5-20 individuals. Groups undertake long-distance movements in search of food under the leadership of a dominant female. Movements have been described as nomadic, but rainfall can trigger directed movements. Females in these herds are ranked, with well-marked dominance and subordination rituals. The extreme defecation crouch of the male Addax (and other oryx species) is a striking visual and olfactory act that advertises rank. Surplus males apparently tend to associate with groups of Dama Gazelles ( Nanger dama).

Status and Conservation. CITES Appendix I. Classified as Critically Endangered on The IUCN Red List. Formerly found across the Sahara as far S as 15° N and E across the Nile and into the Middle East. The Addax is almost extinct in the wild, with a maximum of only about 500 individuals over its former vast distributional range. Because the Addax is slow-moving and relatively docile around humans, overexploitation has been the primary cause of population declines, along with loss of prime habitat from extended droughts and encroaching human settlements and associated livestock. The Addax breeds well in captivity and has been introduced into some ranches in Texas and New Mexico, USA, where it can be hunted. There are about 1700 Addaxes in captivity. Reintroductions in Morocco and Tunisia (Jebil National Park) are contemplated, and there are herds in fenced enclosures also in Morocco (Souss-Massa National Park) and Tunisia (Bou-Hedma National Park).

Bibliography. Asa et al. (1996), Claro et al. (1996), Dolan (1966), East (1999), Estes (1991a, 1991b), Haltenorth & Diller (1980), Hummel et al. (2008), Krausman & Casey (2007), Newby & Wacher (2008), Reason & Laird (1988), Spevak et al. (1993), Weigl (2005).

Figures

134. Roan Antelope (Hippotragus equinus), 135. Southern Sable Antelope (Hippotragus niger), 136. Roosevelt's Sable Antelope (Hippotragus roosevelti), 137. Addax (Addax nasomaculatus)

Distribution. Only confirmed existing population in Termit and Tin Toumma regions of EC Niger ; however, there is a recent confirmed sighting from C Mauritania and sporadic records from E Air Mountains in Niger , the Equey region in W Chad , S Algeria , Libya , and the Mali / Mauritania border.