Effects of shade tree removal on birds in coffee agroecosystems in Chiapas, Mexico

Abstract

Coffee agroecosystems with complex shade canopies provide refuges for biodiversity, and reductions in complexity cause biodiversity loss. However, no studies directly compare farms before and after a management shift. We surveyed birds before and after a drastic canopy reduction. We compared abundance and richness of all birds, migrants and residents, and bird guilds, and examined impacts on functional group richness for insect-feeding birds and abundance of two key insectivore groups. Finally, we used confidence inference trees to examine which vegetation variables best explained bird abundance and richness for all birds and different groups. We observed 113 bird species from over 7700 individuals. Surprisingly, there were no changes in cumulative bird richness in the cut and uncut areas; however, bird abundance and mean richness was 3–6 times higher in uncut areas. Abundance and richness of all birds, migrants, residents, and individual guilds was higher in shaded areas, as was functional group richness of insectivores and abundance of key insectivore species. Canopy cover and canopy depth best predicted bird abundance and richness. Birds prey on arthropods including coffee pests. Most coffee farmers eliminate shade trees to increase yields; however, management changes that negatively affect insect-feeding birds may indirectly affect the coffee crop.