Sumatran elephants eat during a celebration for World Elephant Day at the Bali Zoo in Gianyar regency on Bali island on August 12, 2017. / AFP / SONNY TUMBELAKA

Sumatran elephants eat during a celebration for World Elephant Day at the Bali Zoo in Gianyar regency on Bali island on August 12, 2017. / AFP / SONNY TUMBELAKA

Sumatran elephants prepare to eat during a celebration for World Elephant Day at the Bali Zoo in Gianyar regency on Bali island on August 12, 2017. / AFP / SONNY TUMBELAKA

Tourists watch as Sumatran elephants eat during a celebration for World Elephant Day at the Bali Zoo in Gianyar regency on Bali island on August 12, 2017. / AFP / SONNY TUMBELAKA