Rhinos, on Brink of Extinction     Despite their fierce appearance and often ferocious manner, Rhinos are on the brink of . Three of the five remaining species live in Asia. Two more survive but just barely on the savannas of Africa. It's estimated that more than a million black and white rhinos roam the savanna at the turn of the century. Today only about 11 thousand remain in the wild. The rhino's thick skin protects it from natural predators, but even the thickest skin is no match for the hunter's rifle. In the first half of the 20th century, sport hunting and the loss of the open savanna to farming decimated African rhino populations. But today, poachers are the rhino's deadliest enemy.