House finch eye disease was first identified on the East Coast, in Maryland and Virginia. By 2004, it had spread across the country to the Pacific Coast. Recent reports of this disease showing up locally has prompted a column on the subject. How widespread or prevalent it is within our house finch population is an ongoing study.

This contagious disease is caused by a pathogen common in turkeys and chickens. Cornell Laboratory of Ornithology in Ithaca, N.Y., has determined that between 180-300 million house finches died from this infection known as mycoplasmal conjunctivitis. The figures were based on the National Audubon’s Christmas Bird Count of 2000.

The bacterial disease is primarily a respiratory illness but its most noticeable symptom is red, swollen eyes that may be runny or crusted over. Birds may be so seriously infected that they become blind and unable to care for themselves. Infected birds are lethargic and do not fly off with the rest of the flock when it leaves a feeding area. In its advanced stages the birds do not feed. It has also been noted that this infection is probably uncomfortable as infected birds are often seen wiping their faces on branches and trees as a way of wiping or rubbing their eyes.

Mycoplasmal conjunctivitis has recently been reported in other members of the finch family. Goldfinches, purple finches, evening grosbeaks, pine grosbeaks, dark-eyed juncos and house sparrows have been diagnosed as having the infection. There are even some reports of it spreading to nonfinch species such as blue jays and black-capped chickadees.

Cornell has been conducting a House Finch Disease Survey that details the diagnosis of the disease and provides answers for the most frequently asked questions participants may have. One of these being, “Do feeders encourage the spread of conjunctivitis?”

Noting that disease risk is higher among birds when their population is concentrated in small areas, Cornell also states that, “feeding birds may not necessarily increase the rate of disease spread and should not have a net negative impact on the house finch population.”

It is encouraging to learn that the disease has decreased from earlier epidemic proportions and is now restricted to a smaller percentage of the population. The dramatic spread of a few years ago has leveled off. Only 5% to 10% of the eastern house finch population has the disease. Hopefully, that percentage is even less in western finches where it never reached the levels seen in the eastern part of the country.

If you have concerns about birds at your feeders and/or would like to know more about house finch eye disease, visit Cornell’s website:http://www.birds.cornell.edu. Information about the disease, complete with illustrations, is available. You can also sign up as a participant in the House Finch Disease Survey.

Write to Joan Carson, PO Box 217, Poulsbo, WA 98370. Include a self-addressed, stamped envelope for a reply.