The Borneo Orangutan Survival Foundation ( BOSF ) released six more orangutans into their natural habitat on Monday, bringing the total number of the critically endangered species released to 100 individual animals since 2012.
'We dedicate this activity in celebration of World Habitat Day, which falls every Oct. 7,' said BOSF program manager Agus Irwanto on Monday, as quoted by Antara news agency.
The six orangutans that were released were named Acong, Agus, Inge, Mayang, Noel and Siwie.
The orangutans were flown from Balikpapan to Kehje Sewen forest in Muara Wahau, East Kutai, at 11 a.m. local time, on Monday.
Earlier, BOSF staffers and officials had brought the orangutans overland from Samboja Lestari, a conservation area located 50 kilometers north of Balikpapan to Sepinggan Airport, the journey took about an hour.
Kehje Sewen forest is around 600 kilometers north of Balikpapan. From Balikpapan the orangutans were flown on a one-hour flight by Cessna aircraft to Muara Wahau Airport in Miau.
From Muara Wahau Airport, the orangutans were taken to Kehje Sewen by helicopter.
'Due to the long-distance travel and other arrangements, each release costs around Rp 600 million ( US$52,800 ),' said Agus.