Economic research on biodiversity conservation has focused on the costs of conservation reserves and the benefits of intact ecosystems; however, no study has simultaneously considered the costs and benefits of species diversity, a fundamental component of biodiversity. We quantified the costs and benefits of avian biodiversity at a rainforest reserve in Uganda through a combination of economic surveys of tourists, spatial land-use analyses, and species-area relationships. Our results show that revising entrance fees and redistributing ecotourism revenues would protect 114 of 143 forest bird species (80%) under current market conditions. This total would increase to 131 species (≈90%) if entrance fees were optimized to capture the tourist's willingness to pay for forest visits and the chance of seeing increased numbers of bird species. In contrast, the cost of purchasing agricultural land for ecological rehabilitation of the avian habitat would be economically prohibitive. These results suggest that local biodiversity markets could play a positive role in tropical conservation strategies if the appropriate institutions for redistribution can be developed.