Shade grown coffee has become increasingly fashionable among American consumers. The beans are produced and harvested under trees in Central and South America, and the product is generally believed to be more environmentally friendly than the process of growing coffee in open sunshine. Tropical birds, it has been assumed, are better able to make use of the altered landscape of a shade-grown coffee plantation than they are an open-sun coffee area. A new study compares the two styles of coffee plantations, and evaluates the efficacy of using shade grown coffee as a bird conservation measure.
Published in the ESA peer-reviewed journal Ecological Applications (October issue 10,5), the study was led by Dina L. Roberts from the University of Georgia. Roberts and her colleagues Robert Cooper (University of Georgia) and Lisa Petit (Smithsonian Migratory Bird Center) spent two years studying the birds which live in and around the coffee plantations and forests of western Panama. Specifically, the scientists examined mixed-species assemblages of birds that follow swarm raids of army ants. In a phenomenon unique to tropical regions, these birds feed not on the ants themselves, but on other insects which are flushed from the leaf litter by the raiding ants. The swarms provide a unique opportunity to assess how different levels of disturbance may affect different forest bird species, because a wide variety of species typically use the swarms to obtain food. During the course of this study, 126 bird species were observed attending swarms.
The researchers observed and quantified ant-bird interactions in several different landscapes: areas of intact forest; shade growing coffee lands which were adjacent to forests; shade growing areas which were some distance from forested areas; and areas where coffee was grown in full sun.
Ant swarms did not occur in the full sun areas. In all shade coffee and forest plots, however, the abundance of ant swarms was hig
Contact: Alison Gillespie
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Ecological Society of America