<p><br /> A gorilla at Australia's Taronga Zoo in Sydney has been surprising crowds as he walks around upright on his hind legs.<br /> </p><p><br /> Mahale, who is two and a half years old, is a Western Lowland gorilla.<br /> </p><p><br /> According to Taronga Zoo's gorilla keeper Laura Fidler, his human-like behaviour is not entirely new.<br /> </p><p><br /> "We are surprised at how often Mahale does it. He seems to do it all the time," Fidler said.<br /> </p><p><br /> No one knows why he does it, but zoo officials think it is purely out of curiosity.<br /> </p><p><br /> Western Lowland gorillas are endangered and Taronga Zoo is part of a global breeding program.<br /> </p><p><br /> The World Wildlife Fund estimated that there are only 90,000 Western Lowlands gorillas in the wild, with numbers dwindling due to the destruction of their habitat, and the bush-meat trade in Africa.<br /> </p>
