Elephants are regarded as among the most intelligent of mammals and can be trained to work and to perform. Indian elephants are extensively used as beasts of burden, especially in teak forests, where they carry logs with their trunks. They are not considered truly domesticated as they do not breed well in captivity; young animals are captured from the wild. Training and handling take skill, as elephants have complex emotions and vary individually in temperament. African elephants are often said to be less tractable, but they too were formerly used for work, as well as for warfare. Hannibal's army crossed the Alps using African elephants, which were at that time probably found in the Atlas Mts. Elephants seen in zoos and circuses are usually of the Indian species, although the famous Jumbo, who toured the United States in the late 19th cent. giving rides to children, was an African elephant. In Thailand and Myanmar (Burma), so-called white elephants have long been revered; these animals are not truly white but have unusual light-colored skin and other characteristics. Elephants have been extensively hunted for food and for ivory, and their numbers are now greatly reduced. Despite protections in certain areas and a treaty banning the international ivory trade, elephant poaching remains a severe problem.