Bird‐Arthropod Interactions in Fragmented Agroecosystem Landscapes: Possible Effects on Coffee Traits

ABSTRACT Trophic interactions between birds, arthropods and plants are expected to be altered by anthropogenic factors, particularly in tropical mountain agroecosystems, where fragmentation affects ecological networks. However, little is known about how changes in forest cover influence insectivorous bird diversity and, in turn, affect arthropod communities and coffee crop productivity. In this study, we investigated how the extent of natural and semi‐natural forest cover impacts bird‐arthropod interactions and coffee plant traits in the Colombian Andes by combining bird and arthropod censuses, diet analysis and exclusion experiments. For 6 months, we conducted standardised mist‐net bird sampling and faecal analyses to assess bird diets in coffee plantations, and we implemented bird exclusion treatments in four farms with varying forest cover. We assessed arthropod communities and vegetative and reproductive traits of Coffea arabica (Castillo variety) in both control and bird‐excluded plants. We recorded 56 insectivorous bird species, with higher diversity and food web functionality in farms with greater forest cover. Key insectivorous birds, such as the Spot‐breasted Woodpecker ( Colaptes punctigula ) and the Golden‐crowned Warbler ( Basileuterus culicivorus ), primarily consumed arthropods from the orders Hymenoptera and Coleoptera. Bird exclusion increased arthropod biomass by 330%, species diversity by 33.4%, and abundance by 78.7% compared to control plants. Reproductive traits of coffee plants, such as fruit number, seed weight, fruit diameter and sugar content, were negatively associated with arthropod biomass and abundance but positively correlated with the abundance of predatory arthropods. These results supported the hypothesis that the greater the extent of forest cover, the greater the diversity of birds forming the insectivory network, and that coffee plants from which birds are excluded exhibit higher abundance or biomass of phytophagous arthropods, thereby affecting foliar and reproductive traits. The study underscores the importance of preserving natural and semi‐natural forest remnants as safe habitats for insectivorous birds in coffee plantations.