Tuesday, May 28, 2013
I thought it was a little unusual. A newly fledged House Finch was perched over the same hanging basket on the porch where another pair had raised their brood earlier this season. I had moved the hanging plant to another spot and removed the three nests this pair had built. After that, they didn't come back. What was unusual was that the baby stayed in the same place for over an hour. I took this photo after it had been there all that time, but I didn't really look at it in the camera.
I happened to look out the window a little while later and saw both parents with it on the hanging basket, then they flew into the trees on the edge of the yard. The chick followed, but it appeared clumsy in flight and had trouble landing on a branch. It was only then I began to suspect something was wrong with it.
After taking a couple more photos and looking at them on camera, I realized the chick had an eye disease I had seen on a couple of finches a few years ago. It is called mycoplasmal conjunctivitis, a bacterial infection that renders the bird all but blind. It actually is transmitted as a respiratory infection.
The parents would fly in to feed it every so often followed by the other young from the same brood. These other chicks seemed to be unaffected. The chick mostly sat on a tree limb, occasionally scraping it's eyes on the branch to try to clear them.
The disease was initially seen in House Finches in the winter of 1993-94 right here in Maryland and in neighboring Virginia. It has since spread throughout the East Coast. It mainly effects this one species although it has occasionally been seen in a few other finch species and is also found in domestic turkeys and chickens. The disease, rampant at first, has stabilized over time. Birds that have had the disease and survived do not appear to build up an immunity to future infection. It is estimated that 5-10% of the population has the disease at any one time.