Influences of fruit diversity and abundance on bird use of two shaded coffee plantations

We studied avian foraging at two shaded coffee plantations in Ciales, Puerto Rico. Both coffee plantations contained patches of second-growth forest but differed in shade types; one was a rustic plantation with a species-diverse shade including many fruiting plant species and the other was a commercial polyculture shaded almost solely by Inga vera. We quantified foraging activity of five fruit-eating bird species (Euphonia musica, Loxigilla portoricensis, Nesospingus speculiferus, Spindalis portoricensis, and Vireo altiloquous) and monthly fruit abundance in the coffee plantation and adjacent second-growth forest habitats at each site. Fruits comprised more than 50 percent of the diets for four of five focal bird species. We found a significant difference in the number of foraging records for focal bird species between coffee and forest habitats in the commercial polyculture but found few differences between these habitats in the rustic coffee farm. Overall, foraging activity was positively correlated with the abundance of fruits across study sites. Bird foraging was concentrated on plant species in the genera Cecropia, Miconia, Schefflera, Phoradendron, and Guarea, which together accounted for over 50 percent of frugivory records. Plant species in such genera fruited over prolonged time periods and provided birds with a fairly constant fruit supply. Our findings underscore the importance of fruiting plant species in making coffee plantations suitable habitat for birds and suggest that native fruiting plants be incorporated in coffee farms for avian conservation.