Indonesia
Borneo Nature Foundation - Support orangutan conservation in the tropical jungles of Sebangau National Park and Rungen Forest in Borneo. Volunteers are involved in conservation and youth education activities. No prior field experience necessary; 18 years and up. BNF Volunteer Brochure.
Little FireFace Project - Get involved in the first ever long-term project studying wild slow loris at the LFP field site in Java. LFT provides other opportunities for trained scientists, such as research about slow and slender lorises in the illegal wildlife trade, captive care in rescues centres, their population status, habitat use, diet and so much more.
The Kukang Rescue Program - Based in Sumatra, this organisation has many volunteering opportunities available, both in-country and internationally, with the first Sumatran rescue centre for slow lorises.
Philippine Tarsier Foundation - A non-profit organisation offering volunteering opportunities from 1 week up to 3 months on Bohol.
Selamatkan Yaki - Volunteer for the Critically Endangered Sulawesi crested black macaque through in- and ex situ research, education, and improving ecotourism infrastructure and sustainable development to address their conservation objectives.
Laos
Lao Conservation Trust for Wildlife - Volunteer with a variety of rescued and rehabilitating wildlife affected by the illegal wildlife trade, including husbandry, enrichment and veterinary opportunities.
Singapore
Wildlife Reserves Singapore - Volunteering opportunities are available within the four zoos under the WRS umbrella: Singapore Zoo, Night Safari, River Safari and Jurong Bird Park.
Thailand
Gibbon Rehabilitation Project - Currently seeking in-country volunteers here.
Wildlife Rescue Centre, Wildlife Friends Foundation Thailand (WFFT) - Volunteering opportunities at the rescue centre. WFFT also has a gibbon release research project.
Vietnam
Endangered Asian Species Trust (EAST) - Volunteering opportunities available and also university research projects at the Dao Tien Endangered Primate Species Centre.
Endangered Primate Rescue Centre (EPRC) - Volunteering opportunities at the EPRC in Cuc Phuong National Park, with a range of primates, confiscated by the Vietnamese authorities, including gibbon and langur species.