Fruit Supplementation Affects Birds but not Arthropod Predation by Birds in Costa Rican Agroforestry Systems

As the global demand for the reliable provision of virtually all ecosystem services increases, it is imperative to conduct experimental research that tests specific mechanisms or drivers of the ecological processes that link to services, and whether these management actions can affect biodiversity and processes synergistically. Agroforestry systems are ideal for such experiments due to their increased uniformity and the relative ease with which factors can be manipulated and isolated. Manipulating the availability of food resources, we carried out an experimental test of this potential driver on bird diversity measures and the predatory services provided by birds in coffee agroforests. We constructed exclosures over coffee plants to measure arthropod removal intensity by birds comparing coffee agroforests with and without food resource (fruit) enrichment (the driver). Fruit enrichment agroforests had significantly greater bird species density (50%), overall abundance (55%), and abundance of understory insectivore specialists (89%) compared with control agroforests. Although 48 percent more arthropods were aspirated from coffee plants inside exclosures compared to coffee plants outside exclosures, fruit resource enrichment did not influence predatory activity by birds in the agroforests. The results of this study highlight the difficulties associated with managing lands for ecosystem services in complex ecosystems‐ management actions aimed at increasing numbers of the organisms involved in the interactions of ecological processes is not always equivalent to managing for an increase in the process itself.