Ecosystem services to people are usually assessed at the level of entire ecosystems or large groups of organisms. However, the direct and indirect contributions of biodiversity to ecosystem services, especially at the species level, are complex to understand. The translation of biodiversity-linked ecological functions to ecosystem services is not linear, and has to be often assessed based on indirect and correlative evidence. Additionally, some elements of biodiversity can be both beneficial and harmful to people when examined over space and time. This may lead to biodiversity-driven ecosystem services as well as disservices, creating both synergies and trade-offs for people. It is therefore important to assess the contexts and processes through which ecological functions sustained by specific biodiversity are valued as beneficial or as harmful by clearly identified human actors.

Bats (Mammalia: Chiroptera) are an ideal system to study the tenuous links between biodiversity and trade-offs in ecosystem services, as they can be simultaneously beneficial and harmful to people who they share space with. Frugivorous and insectivorous bats are important seed dispersers, pollinators, and insect-pest controllers, but also cause economic losses to fruit orchards or act as disease reservoirs. Benefits and costs from bats have not been assessed through the ecosystem services perspective, along with emerging zoonotic risks, which together can have consequences both for bat conservation and human well-being. In my PhD research, I addressed this knowledge gap by assessing the simultaneous benefits, costs, and risks from bats to people in agroforestry systems along the Western Ghats. The first two data chapters included studies on seed dispersal, costs of fruit damage, and viral zoonotic risks from fruit bats. The next three data chapters included studies on insectivorous bat activity across land-cover types, insect predation and pest control services from bats, and effectiveness of bat droppings (guano) as agricultural fertilizer and costs of bio-fouling from guano.