Identifying crow dieases: Avian pox

Recently, I received an email from someone in distress over an obviously sick crow in their yard. They sent some photos and were wondering about the cause of the crusty areas around the bill and eyes. Although I am by no means an expert in avian diseases, there’s one that’s easy to identify and by far the most common I see in the field so I feel it’s appropriate to provide a brief description of it here.

Bird with a likely avian pox infection as identified by the whitish/pink lesions around the exposed skin.  Photo c/o D. Wright

Bird with a likely avian pox infection as identified by the whitish/pink lesions around the exposed skin. Photo c/o D. Wright

Avian pox is a common disease affecting birds across many different orders including songbirds, raptors and game birds. It’s caused by the avipoxvirus of which there are at least 3 different strains. There’s multiple modes of transmission but it’s most often spread by mosquitoes which is why it’s observed more commonly in the spring and summer months. It can also be spread via direct transmission or indirectly through inhalation of dander, feather debris or sharing contaminated food or water sources (a good reminder to regularly clean feeders and bird baths).

There are two types of avian pox: wet and dry. Wet pox affects the mouth, throat, trachea and lungs and is most likely to be fatal because it can eventually cause suffocation. Dry pox infections are easy to identify because they result in visible lesions and scarring on the non feathered areas of the bird. In the early stages small yellow, white or pink blisters form which become large raised areas that eventually burst. This results in the formation of crusty scabs that, on crows, will appear brown or black. As long as the the bird’s ability to feed isn’t influenced by the location of the scabbing the lesions will generally heal in 2-4 weeks. The general health of the bird before the infection, and the presence of any secondary infections that result from the open lesions will influence the bird’s likelihood of survival.

The pox covered feet of a crow fatally weakened by this disease.

The pox covered feet of a crow fatally weakened by this disease. c/o Sarah Ramirez

If you notice pox infected birds at your feeder(s) the best way to protect your visitors is to stop feeding them. This may seem cruel or counterproductive since sick birds need access to consist food sources to fight the infection, but providing food bonanzas concentrate birds and increases the risk of transmission to healthy individuals. Depending on your situation you may be able to provide food to the individual without worry of creating contact between multiple birds.

Please leave a message in the comments if you have high quality photos of your infected birds and would be willing to let me use them in this post.  Thank you!

11 Comments

Filed under Crow disease, Crow life history

11 responses to “Identifying crow dieases: Avian pox

  1. Pingback: Crowpocalypse 2015 | The Urban Nature Enthusiast

  2. Diana

    Hi , my name is Diana and I live in in Vancouver. I have a family of crows that frequents my back yard and has for years. I have noticed for 3 years in a row that they have only had one baby and that each year it was riddled with the Avian Pox. Nothing on the parents at all….I did feed the baby when I could and the one last year practically fed from my hand……the parents would always look at me curiously when it did that. Despite my best efforts I do believe that none of them survived. I have front yard crows as well…….I was lucky enough to have them build a nest right under my bedroom window in a tree…….I could see the babies being raised which I think is a rare thing. I have a few pictures but they are not very clear.
    I do however have some good ones of the babies with the pox. I also taught the parent to say “Hello” which he does frequently when he wants food. It’s such a shame that so many people think of these birds as a nuisance …I find them fascinating .

    • Jean

      I think one of the crows frequenting my backyard may have pox. I noticed a bump/sore close to its bill. I am glad to have found this site because I was wondering what it might be. It is eating and its feathers are fine but it is very noisy. It often makes motions as if it wants to be fed by other crows. I am sure it is past the fledgling stage. I wonder if it is in distress.

      The other birds are fine – so far. I don’t want to stop feeding them all as we are developing a relationship.

      If a crow survives the initial infection, do I see the lesion etc disappear?

      • Hi Jean, yes you’ll see the lesions scab over and heal with time. It is not unusual, however, to see young begging from parents even into the next years breeding season, provided they don’t disperse.

      • Jean

        I am aware that a past year offspring will hang around into the next breeding season. I have heard that they even help raise the next fledglings. I was not aware that they still wanted feeding. I told my husband that I am sure the crow is saying “Ma, ma, ma” NOT “caw, caw, caw”

        My mission is to have people appreciate crows for the amazing creatures they are. I have won over a lot of converts.

  3. Diana

    how do I submit a photo of a bird with Avian pox?

    • Hi Diana, you can’t submit photos to the website. Are you looking to confirm that a bird has pox?

      • Diana Seear

        No, I am very familiar with the disease, I just have an interesting photo of a bird with pox who ended up dying in my arms… He was on the road and not able to move, I picked him up and was going to take him to a wildlife rehab when I noticed how advanced his pox was. He had only a small one under his eye but large bulbous lesions on the top of his legs. He died as I was getting him into the box.

  4. Marie

    Is there any medication one can give this bird we have that comes to eat every morning. He is not afraid and comes very close to us.

    • Hi Marie, since it’s caused by a virus there’s no remedy you can acquire from a vet or OTC. Main worry with dry pic is secondary infections so just make sure to keep your feeding area clean and try and prevent contact with other birds. Best wishes for a full recovery

  5. Pingback: Have you ever seen a caramel crow?  | Corvid Research

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