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Keeping It Clean: Bird Feeder Diseases and Challenges

Salmonellosis outbreaks are common at bird feeders in late winter and early spring. The Evening Grosbeak in this photograph is likely to be suffering from Salmonellosis, as her puffed up appearance and swollen eyes attest. The bird in the corner of the photograph shows a healthy grosbeak.

In early spring, as feeders become overrun with new birds migrating through our area and our ever active population of local year-round birds continue to dine, those of us who enjoy feeding the wild birds face a series of interesting — and sometimes heartbreaking — challenges.

One of the issues that I have found most challenging is the recent influx of owls, hawks and other meat-eating birds to my backyard.

There are no less than five different species of hawks and four different owls hunting and haunting my backyard on any given day or night. I have seen many injured birds at my feeders and spotted several piles of feathers and pairs of wings while out walking.

When my bird feeders become a self-serve dinette station for birds of prey, I am saddened by the sight. But, it’s just nature taking its course. Birds of prey need to eat too.

Ill health and disease are part of Nature’s ways also, but there are ways that we contribute to Nature’s despicable way of getting rid of the weak and the helpless — through our dirty bird feeders, bird baths and nesting boxes.

The photographs included with this story may be hard to look at, but the sight a diseased bird at your own feeder at home is heartbreaking.

You can help your wild birds by knowing the signs and learning how to prevent the spread of disease.

Deadly Encounters

This Purple Finch suffers from Avian Pox, a disease which causes wart-like growths to appear on the featherless areas of the body — the eye, the base of the bill, the legs, and feet. There is no evidence that avipoxvirus affects humans.

Avian Pox

Two forms of avian pox exist. In one form, wart-like growths appear on the featherless areas of the body — around the eye, at the base of the bill, and on the legs and feet.

In the second form, plaques develop on the mucous membrane of the mouth, throat, trachea, and lungs, resulting in impaired breathing and difficulty feeding. These birds eventually starve to death.

Avian pox can be caused by several strains of the pox virus and has been reported in at least 60 species of birds, including turkeys, hawks, owls, and sparrows. The virus can be spread by direct contact with infected birds or contaminated surfaces or by ingestion of contaminated food or water.

Mold: Aspergillosis

Bird seed left to mold in feeders or on the ground is a killer.

Ground feeders such as juncos, sparrows, Mourning Doves and pigeons contract aspergillosis by inhaling mold spores. It can also be a serious problem for waterfowl.

Aspergillosis attacks the lungs, air sacs, and occasionally the windpipe. Look for birds at your feeders that gasp and wheeze or sit quietly for long periods of time.

This male House Finch is likely suffering from the early stages of avian conjunctivitis (House Finch Eye Disease), a form of conjunctivitis.

House Finch Eye Disease

Avian conjunctivitis (commonly referred to as House Finch disease) can also affect the American Goldfinch, Purple Finch, Evening Grosbeak and Pine Grosbeak.

Symptoms include swollen eyes, oozing and crusty eyes, but this is primarily a respiratory infection.

You may see an infected bird sitting quietly in your yard, clumsily scratching an eye against its foot or on a perch. Some infected birds recover, but many die from starvation, exposure, or predation.


Salmonellosis has been seen in many avian species throughout the world including the following local birds: American Goldfinch, Bald Eagle, Black-capped Chickadee, Brown Creeper, Cooper’s hawk, Dark-eyed Junco, Double-crested Cormorant, Evening Grosbeak, Great Blue Heron, House Finch, House Sparrow, Mallard duck and, what seems to be the most common of all the suffers in our area, the Pine Siskin.

Salmonellosis is transmitted directly through fecal contaminated food products or from bird to bird.

Signs range from sudden death to a gradual onset of depression over 1 to 3 days, accompanied by huddling of the birds, fluffed-up feathers, unsteadiness, shivering, loss of appetite, markedly increased or absence of thirst, rapid loss of weight, accelerated respiration and watery yellow, green or blood-tinged droppings.

How You Can Help

Mourning Dove found near death, sitting beneath the bird feeders on an icy cold January morning.

If you see sick birds, take down your bird feeders and put them away for at least 1 week and up to 4 weeks.

With the food supply removed, birds will be dispersed, and the carrier and susceptible birds will be separated.

How to Clean Bird Feeders

Clean your feeders about once every two weeks, more often during times of heavy use.

For best results wash your feeder thoroughly in soapy water, then soak or rinse it in a solution of one part bleach to nine parts water. Dry the feeder thoroughly before refilling.

There are products available at local feed stores that are specifically made to dissolve bird droppings and old feed crust. These products can be used on wood, plastic, glass or metal. After cleaning feeders with these products, you must still disinfect with a bleach solution.

Hummingbird feeders should be cleaned every time you refill the nectar (every three to five days).

Kimberly Mason is a freelance writer and photojournalist. She is the founder of The (Almost) Daily News website, loves playing Words with Friends, and probably spends more money on bird seed each month than she probably should. You can find her on Facebook, call her with questions or outdoors news tips at 360-269-5017, or email her at kim@almostdailynews.com.

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