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House Finches face multiple disease threats

September 5, 2011

FeederWatch data show that House Finch populations have declined dramatically since the mid-1990s, and recent research from California suggests that West Nile virus may be contributing to the declines. Researchers Anne Pellegrini and colleagues reported on the survival rates of House Finches in Sacramento County before and after the arrival of West Nile virus in the area*. The researchers took blood samples from wild House Finches and tested mosquitoes (the primary vector for the virus) for infection in order to pinpoint the arrival of the disease. They first detected infected mosquitoes in the county in late 2004. Before the virus arrived, annual survival for House Finches from 2001-2004 was approximately 0.59 (meaning that 59% of birds would survive from one year to the next, on average). Following the arrival of West Nile virus, annual survival probabilities dropped to 0.47 from 2005-2008. The researchers concluded that West Nile virus was contributing to further population declines in House Finches in their area.

Male House Finch by Maria Corcasas.

West Nile virus first appeared in North America in the New York City area in 1999. It rapidly spread across the continent and affected many species of birds in addition to humans, horses, dogs, and other animals. Crows, jays, and other members of the Corvid family were particularly hard hit by the disease. Laboratory studies revealed that approximately 60% of House Finches infected with West Nile virus were killed by the infection. But 40% recovered, and the presence of antibodies against the virus in apparently healthy wild finches suggests that recovery is possible in the wild as well. Further, these survivors have immunity against subsequent infections.

In addition to West Nile virus, House Finches have proven highly susceptible to the “House Finch Eye Disease” caused by the bacteria Mycoplasma gallisepticum, and to avian pox, caused by a virus. Although the combination of these three challenges has certainly contributed to widespread population declines, the House Finch remains one of the most common birds seen at feeders in much of the continental U.S. and southern Canada.

For more information about House Finches, visit the species account on All About Birds.

* Pellegrini, A.R., S. Wright, W. K. Reisen, B. Treiterer, and H. B. Ernest. 2011. Annual survival of House Finches in relation to West Nile virus. Condor 113:233-238.

16 Comments
  1. Peg De Lamater permalink
    October 20, 2011 3:24 pm

    Question: can the virus spread to other birds besides finches? I have had sick finches on my feeders and now have seen cardinals (two males and one female) that are obviously ill so I am wondering if there is any connection?

    • October 20, 2011 4:04 pm

      Peg:

      Yes, Mycoplasmal conjunctivitis can indeed spread to other species, but it generally doesn’t affect other species as strongly as House Finches. Other members of the finch family, including American Goldfinch, are most often affected. Recent research indicates that many species carry the bacteria but few become symptomatic. A large proportion of the chickadees that we study locally, for instance, carry antibodies for the disease. Yet it generally doesn’t cause a respiratory infection or swollen eyes in most birds.

  2. GariRae permalink
    January 28, 2012 12:51 pm

    Within the past 24 hours, I’ve identified 5 house finch with inflamed facial tumors. These tumors are under the left eye at the jaw line and dont appear to interfere with seeing or feeding, despite the size (1/2 inch ball). This is out of a returning flock of only ~15 birds. I live in Sacramento County. Are there any researchers I could report this to?

    • January 31, 2012 10:25 am

      Hi GariRae,

      This could be avian pox (read a bit about it here). If you can get a photo of one of the birds, send it along to feederwatch @ cornell.edu (remove the spaces) and we’ll take a look. If you are a FeederWatcher, you should fill out a Sick Bird Form so that we can include it in our data.

      • Stephannie Smith permalink
        August 4, 2012 6:46 pm

        Within the past month, I’ve had two house finches at different times with the same facial tumor. The first, a male, has died. The second, a juvenile female is still coming to the feeder. What should I do? I don’t want to stress it by trying to catch it, but don’t want it to suffer, either. Is there something I can add to the water or food that all the sparrows and finches access? I live in Broken Arrow, OK.

      • August 8, 2012 3:58 pm

        Anyone who encounters a sick or injured bird should remember that it is actually illegal under federal law to possess or treat a wild bird. If you do encounter a sick or injured bird, your best bet is to contact a licensed wildlife rehabilitator (you can find one in your area here http://wildliferehabinfo.org/). For other information on sick birds, see our page on the topic or follow the links provided on that page.

      • GariRae Gray permalink
        August 8, 2012 5:17 pm

        The birds I encountered in Jan 2012 did have avian pox, confirmed after researching other sites and photos. The recommendation from experts was to remove all feeders to disperse the birds and prevent the spread of the disease. I have to be honest that I did not do that as I had migratory wintering birds using the feeders and I wasn’t going to deprive them of food during the coldest month winter. Here’s what I observed: In over 15 years of feeding birds at this house, I have not observed avian pox in any other species than the house finch; 2) I believe that the pox was confined to one flock of house finch as I might see 4-5 infected birds within 5 minutes, then 30 minutes later, none of the house finch would have the pox. I might be wrong, but I do believe there were two distinct house finch flocks using my feeders and only one flock had the disease. By March, I observed no house finch nor other species of birds with the disease, nor have any of my summering house finch showed the disease. Other wintering and resident species NOT EVER having displayed avian pox (over 15 years), despite using the same feeders as infected house finch: Ore. juncos, Amer, goldfinch, white and gold crowned sparrows, house sparrows, mourning dove, scrub jay.

  3. Laura permalink
    September 23, 2012 4:35 pm

    Hi GariRae, i have a flock of 5 house finches with avian pox.. at least 5 that i’ve noticed so far. today was the first day i have seen the sick birds, and the first time i’ve ever encountered this in 13 years of feeding. My main concern and what I wanted to know from you is what did you do about your bird bath if you have one? I’m guessing that water would be the easiest method of transport of this disease. I can’t just stop feeding the birds water as it hasn’t rained in months and there are no puddles anywhere; they are very dependant on my water supply! do i get rid of the water for now and hope for the best? i would rather wait until it rains but i’m worried about this disease spreading. i phoned wildlife rescue and they want me to bring in all of the sick birds – catch them all with a butterfly net. I don’t know if I can do that, I don’t have time for that.

    Anyways, let me know what you think about my water situation. thanks.

    • September 24, 2012 10:07 am

      Laura,

      In general, birds are very resourceful. They should b able to find water elsewhere if you remove yours for a while, just as they would be able to find food in natural areas if your feeders were not present. If you have a few birds with avian pox, the best thing you can do is take down feeders and bird baths and give them a thorough cleaning. Keep them down for at least a week. Preventing the spread of the disease is important. If you do have the time, it would be good to take the sick birds to your local rehabilitator.

  4. November 12, 2012 1:04 pm

    I have just got my winter birdfeeding stations set up and a purple finch wiht what appears to be conjunctivitis has begun feeding, in addition to about a hundred other birds. Is there any treatment available for sick birds? I know my feeders were clean when I set up the station less than a week ago. Should I still take them down and clean them again?

    • November 12, 2012 3:03 pm

      Hi Sue,

      It might be a good idea to take down and clean the feeders, even though you just put them up. That one sick finch can contaminate the feeders, thus spreading the conjunctivitis to other birds. This is specially true if you have a feeder where the birds have to stick their head in to grab seeds. If you haven’t already, you can learn a bit more about sick birds and how to clean your feeders here: http://www.birds.cornell.edu/pfw/AboutBirdsandFeeding/DiseasedBirds.htm

  5. Melissa permalink
    December 10, 2012 2:15 pm

    Three times this year I have noticed a House Finch with eye disease. Most recently yesterday. I regularly clean my feeders and always keep them full with fresh seed. The two other times I saw a sick finch I took all my feeders down, cleaned them in 10% bleach (I normally use vinegar and soap as I hate using bleach),and waited a few days to rehang them. I am not sure what to do this time. As winter is trying to set in I have a lot of visitors and I feel it’s unfair to the birds that visit daily to take all my feeders down. I would never want to contribute to the spread of the disease but don’t see how my feeders will not become reinfected as soon as I clean them and put them back out. I read the disease has a an incubation time that can be up to two weeks in some finches. I just cleaned the feeders less than a week ago and will now be throwing out about $20 in seed. Should i discard all the seed in the feeders also? I have different types of feeders including platform and port style. I was also wondering if the port style feeder could aid in the spread of the disease more than the platform type. This type requires the bird to stick it’s beak into the port to reach the seed and I’m sure the infected eye grazes the side of the port occasionally. Thanks for any insight you provide! It just makes my stomach sick when I see a sick bird! They truly add to the enjoyment of my life and I would never want to be aiding in the spread of disease! 

    • December 11, 2012 10:00 am

      Hi Melissa,

      Unfortunately, taking the feeders down and cleaning them is your best bet for slowing the spread of the disease. You are also correct that the port-style feeders contribute more to the spread of eye disease, since the birds can swipe their infected eyes along the port while eating. You may find that your birds return quickly once you put your feeders back up. We do suggest that you leave them down for about a week, but don’t worry – there is plenty of natural food out there for birds to eat while your feeders are down.

      In case you haven’t seen it, check out our Diseased Birds page here: http://www.birds.cornell.edu/pfw/AboutBirdsandFeeding/DiseasedBirds.htm

  6. Matt T permalink
    January 23, 2013 2:04 am

    Use these feeders http://www.wbu.com/ecoclean/usa/

  7. April 8, 2013 6:49 pm

    I had a very sick bird last year in my feeder. He laid down on the tray and didnt move for days. His eyes were even covered over. susan Backyardfeatheredfriends.com

  8. Suzie permalink
    August 13, 2013 2:38 pm

    I haven’t seen a house finch in my yard for at least 2 years now. They used to be the most abundant bird in our neighborhood.

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