Forests need apes as much as the apes need the forests. They are the gardeners of the forest - keystone species in the ecology of African and Southeast Asian forests, dispersing seeds, creating light gaps and pruning branch-tips whilst feeding. Their habitat comprises two of the planet's three major tropical forest blocks that are essential for global climate regulation. But the economic pressures that are destroying ape habitats are much greater than current available conservation finance. This unique case study from the Kibale national park illustrates how biological research has had diverse consequences for conservation. It examines effects on habitat management, community relations, ecotourism and training. Lessons learned from this project over the last 20 years will inspire researchers and conservationists to work together to promote biodiversity through field projects.