Care and Safety

Why Does the Bird at My Feeder Have Growths on Its Feet and Face?

Warty lumps on the bare skin of a finch, dove or cardinal are almost always avian pox. The feeders and bird bath come down for at least two weeks, and the reason is how long the virus lasts on a perch.

Wart-like growths on a feeder bird's bare feet, legs, bill base or eye rims are, in North America, most likely the dry form of avian pox. It is a virus, spread mainly by mosquitoes and also through broken skin from contaminated feeders and perches, and the Cornell Wildlife Health Lab has recorded it in over 200 wild bird species, finches and mourning doves among the most common.

Take every feeder and the bird bath down, disinfect them in 1 part household bleach to 9 parts water, and keep them down for at least two weeks, longer if birds with growths are still coming in. Cornell says avian pox does not infect people, and Missouri finds no evidence it affects mammals. It does infect chickens and pet birds.

What pox looks like, stage by stage#

Cornell describes the dry form as "slowly developing wart-like growths on the featherless parts of the bird": feet and legs, the base of the beak, around the eyes. Wisconsin adds the bare skin of the head and neck. The Michigan DNR's wildlife disease manual gives the sequence, which is why two people can describe the same disease so differently:

1. Blister. A small white, pink or yellow vesicle on bare skin.
2. Nodule. The blisters grow, run together and burst, and the fluid crusts into scabs.
3. Dark wart. The surface turns rough and dry and darkens to brown or black.
4. Scar. The scab falls off and a scar forms. Michigan gives 2 to 4 weeks for the skin to heal, provided the growths are not so large the bird cannot feed.

The wet form sits inside the bird: yellow or white, moist, cheese-like plaques in the mouth, throat and windpipe. Both forms can occur in the same bird, and Michigan's list of signs also includes conjunctivitis and swollen eyelids.

Pox or something else: the look-alikes side by side#

Three questions sort most birds. Lumps or crust? Pox makes separate raised lumps, crusted on top once they mature; scaly leg is a crust spread over the leg itself. One place or several? A finch with a swollen eye and a lump at the base of its bill or on a toe is a pox bird, because eye disease shows in the eyes. One bird or several? One bird with one swollen foot could be bumblefoot from a single wound. Several birds with growths in the same summer is an outbreak, and pox is the only outbreak disease here that puts lumps on the feet.

Know the limits of the last three rows: the BTO describes them from British garden birds, and none of the four North American agency pages used here mentions them. Use them to rule pox out, not to diagnose. Even pox is a field call; Cornell says confirmation takes PCR, virus isolation or microscopy.

Which birds get it#

Cornell names finches, mourning doves, bobwhite quail and wild turkeys, and says young birds are hit harder. Michigan's manual lists 22 species diagnosed in that state, about half of them feeder regulars: American goldfinch, house finch, northern cardinal, black-capped chickadee, American robin, song and chipping sparrows, house sparrow and mourning dove among them.

How it gets from bird to bird#

Mosquitoes are the main route. A mosquito that has fed on an infected bird carries the virus on its mouthparts to the next bird it bites, and Cornell says it can harbor the virus for more than a month. Cornell, Missouri and Michigan all tie pox to seasonal mosquito cycles in warm, humid places.

The feeder is the second route. The virus enters through breaks in the skin or mucous membranes, from contact with an infected bird or with contaminated surfaces, and Cornell names feeders and perches. Michigan names what does the contaminating: virus-laden scabs shed from the growths, which end up in food and water and on feeders, perches and even clothing.

Cornell adds that avipoxviruses are highly resistant to drying and can survive outside a host for months to years, depending on temperature and humidity. Drying a feeder does not finish pox off; bleach does.

Several days or two weeks: how long to keep the feeders down#

The agencies disagree on paper. Missouri says to stop artificial feeding "for several days." Cornell says feeders and baths should be disinfected "and kept down for at least two weeks." Wisconsin gives no number: they "should not be put back up until the affected birds are gone from the area."

Use at least two weeks, and longer while birds with growths are still around. The pause is not there to outlast the virus, which can sit on a surface for months. It is there to break up the crowd, what Cornell calls "removal of feeders and birdbaths to reduce congregating", while infected birds still carry growths. Michigan gives 2 to 4 weeks for skin lesions to heal. Rehang after several days and the same warty-footed bird is back on the same perch, shedding scabs onto it.

Missouri's figure persists because it carries a state agency's name, but the page gives no basis for the number, and the weekly bleach cleaning on the same page is offered as routine maintenance, not outbreak control. Why a long pause costs the birds nothing is covered in do birds depend on feeders, and the other reasons to pause in when to take your feeders down.

What to do today#

1. Take down every feeder and the bird bath. One feeder left up concentrates the flock onto it.
2. Clear the ground. Michigan names food contaminated with shed scabs as a route, so rake up and bag the spilled seed and hulls, as in seed mess, hulls and dead grass, and bin the seed left in the feeders.
3. Scrub, then bleach. Hot soapy water, then 1 part household bleach to 9 parts water, the 10% solution all four agencies name. Rinse and dry. Method: how to clean a bird feeder; why not vinegar: safe disinfectants.
4. Do the perches and poles. Wipe hooks, poles, perches and the rim of the bath with the same solution.
5. Change before the coop. If you keep chickens or a pet bird, wash up and change clothes first. Michigan names clothing as a carrier, and Missouri says all pet and domestic birds, including poultry, are at risk.
6. Rehang one feeder after two weeks with no birds showing growths, and watch it.

Mosquito season and the bird bath#

Cornell says transmission peaks when mosquitoes are abundant and that removing standing water where they breed helps; Missouri and Wisconsin agree. The bird bath is the standing water you put out on purpose, and in pox season it is both a shared surface for scabs and a mosquito nursery where birds gather.

Taking it down during an outbreak deals with both. When it goes back up, follow the bird bath routine: dump, scrub and refill every 2 to 3 days in warm weather rather than topping it up, which is shorter than the time mosquito larvae need to develop. Then tip out plant saucers, gutters and tarps.

Will the bird recover?#

Often. Cornell says most mild cases resolve on their own with minimal scarring, and Wisconsin says birds with mild skin lesions generally recover. Large growths that block vision, feeding or breathing can kill, Cornell says. Michigan states there is no known treatment in wild birds. Put nothing in the seed or water. A bird that cannot see to feed or is struggling to breathe is a case for a licensed wildlife rehabilitator, with the steps in there is a sick bird at my feeder.

When this page does not apply#

• Doves drooling or dying, with cheesy matter in the mouth and no growths on the skin. Wet pox is possible, but canker is the usual dove disease: see why mourning doves are dying under your feeder.
• Fluffed, lethargic finches in winter with no lesions. That is the pattern of salmonella at feeders, which does infect people.
• A chaffinch with warty legs in Britain or Europe. Papillomavirus is a cause the BTO describes there.

When the feeders go back up for the finches, the spread-out, less-seed setup that suits them is in how to attract house and purple finches.