The northern race of the square-lipped rhinoceros Ceratotherium simum cottoni is disappearing in Africa and is now believed extinct in Uganda. Commonly called the white rhinoceros because of its wide (weit) square mouth, it differs from the black rhino in size, habits and disposition. The white rhino occurred naturally in three countries: the West Nile Province of Uganda, north-east Zaire, and the Bahr el Ghazal and Equatorian provinces of Sudan. The Nile limited its eastern spread, although fossils show that it existed in Tanzania some 400,000 years ago. Its extreme southern limit was the river Ora which enters the Nile opposite Wadelai, from where it extended northwards along the western bank of the Nile through to Shambe, and then north-west through the Bahr el Ghazal drainage to the borders of Chad, where in the 1890s it was abundant. Harper reported the collection of many rhino horns yearly in Abecher. At the beginning of this century Sidney described the species as numerous in the upper waters of the Bahr Azoum and the Bahr Aoule, plentiful in the Birao area, fairly numerous north of the Uele river in what is today in Zaire's Garamba National Park, and abundant in Okolo, Aringa and West Madi in Uganda.18Rhinos were so common in all these areas that in 1919 Theodore Roosevelt's headquarters for the Smithsonian African Expedition collecting rhino products was named Rhino Camp. Here in 1932 Captain Pitman encountered 30–40 groups of at least seven individuals each within a day's walk, and he could approach to within 7–8ft because they were unharried by hunters and poachers.
Spatial variability of concentration and aggressiveness of precipitation in North-East of Algeria