A Thesis Submitted in Partial Fulfillment of the Requirements for the Masters of Environmental Studies Program, The Evergreen State College, December 2005. Abstract: The last 15 years have seen the most dramatic and prolonged collapse in coffee prices in the history of the global coffee trade. In response to this "coffee crisis," many coffee farmers have been forced to abandon their land or change to other crops, including cattle pasture. This study looks at the environmental effects of these decisions at a local scale, focusing on the district of Agua Buena in southern Costa Rica. Interviews with 59 farmers were used to assess the nature and extent of land-use change on coffee farms, and 96 timed area-search bird surveys were used to assess the effects on avian communities of conversion of coffee to pasture. The interviews revealed that, in the study area, farmers were changing from coffee to other crops, with 93.3% of respondents listing coffee prices as a motivating factor in their decision. Pasture represented, by area, 64.3% of the land area converted, with other crops and land abandonment representing 15.3% and 14.0%, respectively. The bird surveys showed a reduced diversity at the species level, and reduced richness and diversity at the family level. The bird surveys also revealed changes in community composition with conversion to pasture – most notably the disappearance of four of five detected species of understory insectivores, a nine-fold increase in the relative number of detections of sparrows and finches (family Emberizidae), and a four-fold increase in the relative number of detections of granivores. The study concludes that, due to the scale of conversion of coffee to pasture revealed by the interviews, and the diminished habitat quality in pasture as indicated by the bird surveys, the coffee crisis has had negative effects on biodiversity at a local scale. The conclusions suggest that new price and supply controls are desirable to mitigate both the environmental and social effects of the coffee crisis.