An adult male orangutan has secondary sexual characteristics that are like a man's beard. They only get these features when they reach sexual maturity at around 15 to 20 years old. The other unusual feature of the male orangutan's face is the large sac under their chin. This call is used to attract females and to warn other males to stay out of his territory. The objects are replicas of a durian fruit.
Durians grow in Southeast Asia and are considered a favorite fruit of orangutans.
These artificial durians were created from a latex mold by zoo staff. They are filled with a variety of treats such as pumpkin, jam, applesauce or peanut butter. It is challenging for the orangutans to scrape the contents out from the inside in order to eat it. The big adult twins, Towan and Chinta, and the female Melati were all raised in a nursery by humans. They especially like young children and visitors who come on a regular basis.