Bird functional diversity supports pest control services in a Costa Rican coffee farm

Abstract

Understanding how species functional traits relate to the delivery of ecosystem services is essential to support on-going biodiversity conservation efforts. While much recent work has been conducted, relatively few studies relating functional ecology to ecosystem services has utilized field experiments, particularly for animal species. We used a functional diversity (FD) approach to study the effect of bird traits on the control of the coffee berry borer (Hypothenemus hampei) and the effect of canopy cover management on bird FD. We conducted an exclosure experiment to test the effect of bird FD on the difference of H. hampei infestation rates between coffee shrubs both exposed to, and excluded from bird foraging activity. We addressed the following questions: (1) is avian FD, at the plot level, a good predictor of H. hampei infestation? (2) do gleaner bird species contribute to the control of the pest? and (3) how does shade management affect avian FD? We found that (1) all four FD indices calculated using bird traits were significant predictors of H. hampei differences in infestation rates, (2) richness of gleaning bird species was also a significant predictor of differences in H. hampei infestation rates, and (3) the interaction between month and canopy cover management affects bird FD, however whether this affects delivery of the pest control service remains unclear due to the particular biology of H. hampei. In revealing the connection between avian traits and the removal and potential control of H. hampei, our study highlights the importance of bird diversity persisting in agricultural landscapes, and the necessity of integrating bird conservation to foster healthy production systems.