In 1978 twins Bono and Suma were born to Olga at the Melbourne Zoo. At the time, they were one of only five sets of orang-utan twins born in captivity across the world.

Bono and Suma's mother Olga became very ill soon after their birth and the twins were hand raised by a team of zoo staff, headed by keeper Uli Weiher. Another orang-utan, Girlie, became a foster mother to the two young primates after the death of their mother.

The orang-utan twins became media darlings, with the press and public being fascinated with the work that went on behind the scenes at the zoo.

Further information:

150 years Melbourne Zoo, Zoos Victoria, Bounce Books, 2012