Avian Pox

Last week a friend and I noticed a lone house finch staying quietly on the ground outside my front door when we walked outside. We stopped to watch it, and after a couple of attempts it managed to fly to a perch on the nearby tube feeder. I expected to see the crusted-over eyes of House Finch eye disease, mycoplasmal conjunctivitis, since we have occasionally seen birds with this debilitating condition, as I wrote about in 2010. However, this bird's eyes were not crusted-over or weepy, but one was greatly overshadowed by a warty-looking bump and there was another bump on its beak. (Now that I look at the 2010 photos, I can see a bump on that bird's beak too, which I didn't notice at the time.)

I consulted my ornithologist friend Dan Tallman, who pointed me to information about avian pox, sometimes abbreviated AVP. This is a disease that affects a wide range of both commercial poultry and wild birds. Warty growths appear on non-feathered areas of affected birds; there is also a variant that affects the mucous membranes and causes breathing problems. It's caused by a virus that can be spread by mosquitoes, by direct transmission between birds, and by contaminated surfaces like feeders. (More info: AVP and conjunctivitis in birds at feeders | Pox from a commercial fowl science perspective)

We've taken down the tube and hopper feeders the finches tend to use, to minimize the risk of transmission between birds at the feeders, and will sanitize them before putting them back up. It's a good practice to clean and sanitize (using a solution of nine parts water to one part bleach) bird feeders every couple of weeks, and if signs of illness are present, more often. Let them dry thoroughly before refilling. (More info: Tips on feeder maintenance)