White antelope, Screwhorn antelope
The addax is an antelope of middle size, perfectly suited to living in harsh desert landscapes. A native of the Sahara Desert for thousands of years, it has thrived in regions where few other animals could survive. As with most other antelopes, male and female both have horns, which are slightly spiraled and can be more than a meter long. Their hooves are splayed so that they can travel on sand. Their short, glossy coat is grey-brown in the winter, fading during the summer months to almost white. Out of the antelopes, the addax is the one most adapted to the desert. It drinks very little water, surviving on the moisture from the vegetation it eats.
Found across northern Africa in the past, on both the west and east sides of the Sahara, today addax populations exist in just a fragment of their former range in Chad, Niger, and possibly along the Mali - Mauritania border. These animals inhabit semi-deserts, arid regions, and stony and sandy deserts. They can occur in extremely arid regions that have less than 100 mm rainfall per year. They also live in deserts where tussock grasses and the succulent thorn scrub cornulaca grow.
Addax are active mainly during the night, especially in the hot season; during the day, they will dig 'beds' under shade into the sand to avoid the desert sun’s heat and to shelter from sandstorms. Individual addax can live some distance from one another in their habitat without causing any problems because of their sensory skills whereby they can detect and find each other over huge distances. They are also able to track rainfall, heading for rainy areas where there is more vegetation. Some addax live with others in herds of 5-20 individuals of males and females. The herds usually stay in one place, though they may wander when searching for food. The eldest dominant male usually leads the herd. Females establish a dominance hierarchy, the oldest animals having the highest ranking. Addax are known as "short leg" runners and cannot run very fast, so fall prey to predators which are faster.
Addax exhibit polygynous mating behavior. Males try to establish a territory of their own, attempting to keep breeding females inside the boundaries. A male will mate with a number of females in his territory. Year-round breeding occurs, with birth peaks in early spring and winter. Gestation lasts for 257-264 days, with one young being almost always the case. The calf is hidden for about the first 6 weeks and its mother suckles it 2 – 3 times each day. It is weaned at 23-39 weeks. Males are reproductively mature by about 24 months, and females at the time of the second or third summer.
Addax are slow running, heavily built antelopes and so are easy prey for people with modern weapons. Many resident populations have been decreased or eliminated by hunting in many parts of this animal’s original range. Four-wheel-drive vehicles with tourists also affect addax by chasing them to the point of exhaustion and death. Recent droughts, increasing human population, and desertification of savanna lands have all contributed to decreasing addax populations.
According to the IUCN Red List, the total addax population size is around 30-90 mature individuals. Currently this species is classified as Critically Endangered (CR) and its numbers today are decreasing.