Bats and birds increase crop yield in tropical agroforestry landscapes

• Published in: Ecology letters 2013-12, Vol.16 (12), p.1480-1487
• Main Authors: Maas, Bea, Clough, Yann, Tscharntke, Teja
• Format: Article
• Language: English
• Subjects: Agricultural and farming systems; Agricultural production; Agriculture; Agronomy. Soil science and plant productions; Animal and plant ecology; Animal populations; Animal, plant and microbial ecology; Animals; Araneae; Arthropoda; Arthropods; Aves; Bats; Biodiversity conservation; Biological and medical sciences; biological control; Birds; Cacao - growth & development; Chiroptera; Conservation of Natural Resources; ecosystem services; exclosure field experiment; Food Chain; Forests; Formicidae; Fundamental and applied biological sciences. Psychology; General agroecology. Agricultural and farming systems. Agricultural development. Rural area planning. Landscaping; General agronomy. Plant production; General aspects; Generalities. Agricultural and farming systems. Agricultural development; Herbivory; Indonesia; land-use management; Landscape ecology; Linear Models; Mammalia; mesopredators; multitrophic interactions; Predatory Behavior; shade cover; Southeast Asia; Theobroma cacao; Tropical Climate; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution
• ISSN: 1461-023X; 1461-0248
• DOI: 10.1111/ele.12194

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.