Density-dependent Decline of Host Abundance Resulting From a New Infectious Disease The eye disease affecting House Finch populations has been in poultry populations in the United States since the 1930s. However, the disease was only recently found to affect wild birds, when it was discovered in House Finches in the Washington, DC area in 1993. For this paper, scientists at the Cornell Lab of Ornithology used data contributed by FeederWatchers to describe the rapid movement of this disease across North America. They were able to show that, after the arrival of the disease, House Finch populations declined in areas where they were previously abundant. They found that populations declined most rapidly in areas with large finch populations. Thus, the influence of the disease on finch populations was dependent upon the number of birds in the area. In regions that were seriously impacted by the disease, finch populations stabilized at a lower level after the initial decline. Information stored in the FeederWatch data base proved critical to this research, as population data were available from before and after the disease reached a region. Most studies of infectious disease in wildlife only have data from during and after the outbreak, limiting what scientists can learn about the disease. This article was written by Wesley Hochachka and Andre Dhondt, who are research scientists at the Cornell Lab of Ornithology. It appeared in the May 9, 2000 issue of the Proceedings of the National Academy of Sciences, one of the world’s most prestigious scientific journals. For a more detailed summary of this research, click here.