title: Bats and birds increase crop yield in tropical agroforestry landscapes.
abstract: Human welfare is significantly linked to ecosystem services such as the suppression of pest insects by birds and bats. However, effects of biocontrol services on tropical cash crop yield are still largely unknown. For the first time, we manipulated the access of birds and bats in an exclosure experiment (day, night and full exclosures compared to open controls in Indonesian cacao agroforestry) and quantified the arthropod communities, the fruit development and the final yield over a long time period (15 months). We found that bat and bird exclusion increased insect herbivore abundance, despite the concurrent release of mesopredators such as ants and spiders, and negatively affected fruit development, with final crop yield decreasing by 31% across local (shade cover) and landscape (distance to primary forest) gradients. Our results highlight the tremendous economic impact of common insectivorous birds and bats, which need to become an essential part of sustainable landscape management.
authors.affiliation: Agroecology, University of Goettingen, Grisebachstraße 6, 37077, Goettingen, Germany.
authors.forename: Bea
authors.initials: B
authors.lastname: Maas
authors.forename: Yann
authors.initials: Y
authors.lastname: Clough
authors.forename: Teja
authors.initials: T
authors.lastname: Tscharntke
mesh_terms: D000383:Agriculture; D000818:Animals; D001181:Arthropods; D001717:Birds; D002099:Cacao / Q000254:growth & development; D002685:Chiroptera; D003247:Conservation of Natural Resources; D020387:Food Chain; D065928:Forests; D060434:Herbivory; D007214:Indonesia; D016014:Linear Models; D011235:Predatory Behavior; D014329:Tropical Climate
keywords: Biodiversity conservation; Southeast Asia; Theobroma cacao; biological control; ecosystem services; exclosure field experiment; land-use management; mesopredators; multitrophic interactions; shade cover