Epidemic Mycoplasmal Conjunctivitis in House Finches from Eastern North America. Dhondt, André A., Diane L. Tessaglia, Roger Slothower. 1998. Journal of Wildlife Diseases 34(2): 265-280.

House Finches (Carpodacus mexicanus) with severe conjunctivitis (later shown to be caused by Mycoplasma gallisepticum, a parasitic bacterium) were first observed in suburban Washington D.C. in January 1994. Using a large network of volunteers in eastern North America, most of whom also participate in Project FeederWatch, one of the citizen science projects of the Cornell Lab of Ornithology, we were able to track the prevalence of the disease month by month between November 1994 and March 1997. We use the information on 24,864 monthly data forms to describe the very rapid spread of the conjunctivitis epidemic through the eastern House Finch population. The epidemic first expanded mainly North, probably carried along by House Finches on their return migration, then towards the SE, and later West. By March 1997 conjunctivitis had been reported from most of the eastern range of the House Finch. The prevalence of the disease seemed to fluctuate seasonally, with increases in the fall, probably as a result of dispersing juveniles. House Finch numbers decreased throughout winter in areas with cold winters and high conjunctivitis prevalence, suggesting significant mortality associated with the disease.