Who's Eating Whom and How

One of the more important observations about biodiversity and coffee agroecosystems was that of Russell Greenberg of the Smithsonian Migratory Bird Center, connecting the decline of eastern songbirds with the transformation of coffee farms in Central America, as we noted in Chapter 2. The conservation community could hardly ignore coffee intensification when one of the most iconic symbols of biodiversity, birds, was under threat in this evident albeit indirect fashion. However, birds are more than just biodiversity emblems. Early studies on the effects of birds on arthropods in temperate ecosystems concluded that birds exert little control over arthropods. ¹ However, more recent studies and meta-analyses have shown that vertebrate insectivores, including birds, can be important in reducing arthropod populations. ² Furthermore, recent studies in tropical forests and coffee agroforestry systems found that the effects of birds and bats, ³ and of birds and lizards, ⁴ is additive. These and other studies argue that vertebrate insectivores perform important functions as regulators of arthropods in these systems and may play an important role in the control of herbivores in forests and agricultural systems. ⁵