What Is House Finch Eye Disease?
During the winter of 1993-94, large numbers of house finches with red, swollen and runny eyes were first seen in Virginia and Maryland. The disease spread throughout eastern North America from Quebec to Florida.
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History
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House finches were not found in eastern North America until the 1940s, when pet stores on Long Island that sold them illegally were forced to release them. They survived in the wild, but there were so few house finches that they became inbred, which made them more susceptible to disease than native birds.
Cause
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House finch eye disease is caused by a parasitic bacterium called Mycoplasma gallisepticum, which causes a respiratory disease common in poultry. In the house finch, it shows up as a conjunctivitis, or inflammation of the mucous membrane that lines the inner surface of eyelids.
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Characteristics
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Some cases of the eye disease are so severe that the eye is swollen shut or so crusted over that the bird is blinded. Death comes not from the disease itself, but from the bird's inability to see to find food or shelter or to escape from predators.
Significance
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The disease spreads quickly because of the large population of house finches. Hundreds of them typically gather in flocks and travel over wide areas, infecting other house finches.
Prevention
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Although a number of common antibiotics can clear infections in finches, it is not practical to administer them to the wild birds that visit feeders. To help prevent the spread of house finch eye disease, the experts at Cornell suggest that if you see an infected finch at your feeder, clean the feeder with a 10 percent bleach solution and rake up the fallen seeds and bird droppings from the ground underneath.
Outlook
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Data collected from 1994 to 2009 by "citizen scientists" through such initiatives as Project Feederwatch promoted by the Cornell Lab of Ornithology suggests that the epidemic was slowing down by 2009. Either because the disease lost its virulence, or the birds became more resistant, only 5 to 10 percent of the house finch population appeared to be infected when the Cornell study ended.
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