While staying in Ba Sing Se, Aang found a gloomy and desolated zoo where all the animals were kept in small cages. One of the present beasts was an elephant mandrill, who lay in a pen that was too small for his size. Upon deciding to help the animals, Aang released all the creatures in order to guide them to a larger facility in the Agrarian Zone of the city. However, upon being freed, the elephant mandrill rampaged through the streets of Ba Sing Se, scaring a number of civilians. The animal was out of control until it heard the signal of Aang's bison whistle and followed the sound outside the city's wall, where it ended up in a larger and greener pen in the newly created zoo.