Sunday, September 14, 2008

A Sight for Sore Eyes

It is easy for backyard birders to believe that their flighty populations of eagerly eating guests are happy, healthy, and content, but unfortunately that is not always the case. With some birds, such as Fluffy, illness is apparent through listless, uncharacteristic behavior, while others may visually appear different yet act in no way apart from their peers. That is the case with another distinctive guest at my feeders, Cyclops.

That may seem a cruel name for a bird, but this female house finch suffers from Mycoplasma gallisepticum, better known as house finch eye disease or avian conjunctivitis. First reported in eastern house finch populations in 1994, the disease has spread to western populations and is highly contagious. Symptoms include:
  • Swollen or crusty eyes, possibly swollen shut
  • Excessive wiping of eyes (not beak) on branches
  • Respiratory distress, including coughs or sneezes
  • Disoriented behavior from lack of sight

As the birds grow ill, they have difficulty feeding and are more likely to become scruffy and scraggly, and will often fall prey to predators because they cannot see well enough to seek shelter when necessary to hide. They may seem more approachable at feeders, if only because they do not feel well enough to flee or cannot see well enough to recognize dangers.

Cyclops does not appear to suffer the more pronounced ill effects of this disease; she eats heartily and is as alert and active as her cohorts. While she does feed more frequently alone or away from other birds in the flock, she has no trouble fleeing from any sign of danger. The disease flares and recedes at times, as the swelling may become more or less pronounced. As yet I have not noted any other house finches affected, but the disease is highly contagious. To some birders, this may be a warning sign of failing house finch populations, but the proclivity of the birds precludes that and there is no need to fear that the population numbers will be drastically affected. There are precautions to take in one's backyard, however, including:

  • Regularly clean and disinfect all feeders -- inside and out -- to inhibit the spread of the disease. Tube feeders are especially apt to harbor bacteria because of the limited perching space. If infected birds are observed, clean feeders with a bleach solution of 1 part bleach to 9 parts water.
  • Clean beneath feeders frequently to remove infected seeds or droppings.
  • Remove any dead birds quickly, but do not bury them or dispose of bodies in areas where other birds may come into contact with the remains.
  • Space feeders widely to discourage crowding that could promote the spread of the disease.

I am following my own advice to protect my flock of house finches, I encourage all backyard birders to do the same to keep their own flocks healthy. For more information including additional pictures of infected birds, visit the Cornell Lab of Ornithology.

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