Background/Question/Methods In our increasingly urban world, indigenous knowledge of local ecology is declining rapidly, because survival in industrialized urban environments does not depend on knowing the details of local flora, fauna, or phenologies. While traditional ecological knowledge has been documented since 1980s, this is has been largely descriptive, e.g., ethnobotany of sacred groves, cultivation practices, or use of medicinal plants. Until recently, conservation biologists and managers of protected areas have followed western models of conservation that exclude local people and often abandon local ecological knowledge. However, many scientific studies of local ecosystems would not have been possible without the knowledge-base of indigenous people helping researchers. Yet, careful scientific analysis of such knowledge systems is scarce, except in some commercial applications such as forestry or fisheries. Further, even in rare instances when park managers have recruited knowledgeable locals as partners in PA management, the bureaucracy ended up dissipating ecological knowledge rather than sustaining it. The challenge therefore is to understand the epistemology of ecological knowledge, especially the costs and benefits to local people, to help create novel management regimes which provide new incentives for sustaining such knowledge even as traditional dependencies on natural resources are transformed for long-term sustainability of biodiversity. Results/Conclusions This paper reviews the literature on indigenous ecological knowledge in South Asia, to establish a baseline for systematic epistemological analyses. Examples include the Bihari bird-trappers assisting the Bombay Natural History Society's bird-ringing projects, Irulas helping snake research at Madras Crocodile Bank, Kanis supporting a variety of research projects, including our own, in Kalakad-Mundanthurai Tiger Reserve over the past two decades, and Andamanese who have turned from overharvesting to sustainable cultivation of Edible-nest Swiftlets. We argue that indigenous knowledge is useful not only for monitoring ecosystems or determining use of natural resources, but more importantly for generating fundamental scientific insights, and adding to the knowledge part of our collective social capital. Even as indigenous knowledge is being lost, volunteer-based Citizen Science projects are recruiting amateur naturalists, especially in urban areas, to monitor and study local biodiversity. Such approaches need to be extended into genuinely participatory research programs where indigenous people are engaged in generating and sustaining ecological knowledge, from traditional and modern scientific perspectives, to become well-informed stewards of the socio-ecological systems we inhabit from local to global scales. This is a crucial step towards slowing the loss of biodiversity by reversing our collective loss of knowledge of biodiversity.