Damai, a 3-year-old Bornean orangutan plays on the courtyard at the Surabaya Zoo as he is prepared to be released into the wild, May 19, 2014.

The two baby brothers were found in Kutai National Park in critical condition having been abandoned by their mother on May 14, 2014. The Centre for Orangutan Protection (COP) have since been nursing the animals back to health, treating them for malnourishment and 16 wounds predominantly to the feet and hands.

All photos taken on May 19, 2014.

Damai and Rizki, play in the courtyard at Surabaya Zoo.

Ten-month-old Rizki learns to bite.

Surabaya Zoo keeper Rukin plays with Damai and Rizki.

Rizki eats leaves.

Rizki eats leaves.

Three-year-old Damai plays at the zoo, May 19, 2014.

Damai and Rizki, orphaned Bornean orangutans, play on the courtyard at Surabaya Zoo.

Damai plays at the courtyard of the zoo.

Rizki bites the net.

Damai plays at the courtyard of the zoo.

Rizki bites.

Rizki continues to bite.

Rizki plays on the nets.

Rizki rests.

Damai plays at the courtyard of the zoo.

Rizki learns to bite.

Rizki starts learning to bite and eat leaves.

Damai plays at the courtyard of the zoo.

SURABAYA, INDONESIA - MAY 19: Damai, 3 years old Bornean orang utan plays courtyard at Surabaya Zoo as he prepares to be released into the wild on May 19, 2014 in Surabaya, Indonesia. The two baby orangutans, brothers, were found in Kutai National Park in a critical condition having been abandoned by their mother on May 14, 2014. The Centre for Orangutan Protection (COP) have since been nursing the animals back to health, treating them for malnourishment and 16 wounds predominantly to the feet and hands. (Photo by Robertus Pudyanto/Getty Images)

Damai and Rizki play at the courtyard of the zoo.

Damai and Rizki play at the courtyard of the zoo.

Rizki learns to bite.

Damai and Rizki play on the courtyard at Surabaya Zoo.

Rizki learns to bite.

Damai and Rizki play on the courtyard at Surabaya Zoo.

Rizki learns to bite at Surabaya Zoo.

Rizki learning to bite and eating leaves at Surabaya Zoo.

Rizki learns to bite at Surabaya Zoo.