The Addax (Addax nasomaculatus) is a critically endangered desert antelope that lives in several isolated regions in the Sahara desert. Although extremely rare in its native habitat, it is quite common in captivity and is regularly bred on ranches where they are hunted as trophies. The Addax stands about 1 metre tall at the shoulder and weighs 60 to 120 kilograms. Their coat is white but their chest, neck and head are mainly brown with a white patch over the bridge of the nose and another around the mouth. They have a scraggly beard and prominent red nostrils.During summer their coat is white and during winter it is brown. Horns, found on both males and females, have two twists and can reach 80 centimetres in females and 120 centimetres in males. The hooves are broad with flat soles and strong dewclaws to help them walk on soft sand. Addax live in desert terrain where they eat grass, and leaves of what bushes there are. Addax don't drink, but get all the moisture they need from their food. Addax are nocturnal: they rest during the day in depressions they dig for themselves. Addax herds contain both males and females and have from two to twenty animals, though they had more in previous times. They wander widely in search of food. Addax have a strong social structure, probably based on age, and herds are led by the oldest male. The Israeli Yotvata Hai-Bar Nature Reserve is breeding Addax in the Arava desert for possible release in the Negev desert, although this is outside their natural range. One of the biggest captive breeding herds for Addax exists at the Hanover Zoo, Germany. They are raised there and some groups have been sent to fenced areas in Morocco and Tunisia, from where it is hoped they will be reintroduced into the wild.