As birds crowd to feeders during the winter months, they can spread disease. To keep the birds healthy, it's important to clean their feeders regularly and take precautions as you feed them.
"You can spot sick birds in a crowd," says Dana Sanchez, wildlife biologist with the Oregon State University Extension Service. "They are less alert and less active. They feed less and often cower on a feeder, reluctant to fly. Sick birds are more vulnerable to starvation, dehydration, predation and severe weather."
"Sick birds show up at feeders, and other birds get sick as a consequence," says Sanchez. "But this does not mean that bird feeding should be stopped."
To minimize the spread of disease at your feeder, Sanchez recommends following these steps:
- Give the birds enough space. If you have one feeder that is crowded, consider getting an additional feeder.
- Clean away droppings on the feeder's perching area each time you fill it.
- Disinfect the feeder once or twice a month with one part liquid chlorine household bleach in nine parts warm water. If possible, immerse the feeder for two to three minutes and allow to air dry.
- Feed birds only high-quality food. Moldy seed or bread or spoiled leftovers don't do them any good.
- Keep rodents out of the food. Mice can carry bird diseases.
- When you see sick birds huddled at the feeder, spread the word quickly in your neighborhood.
- Check your feeder for sharp edges where birds might cut themselves. Small scratches or cuts allow bacteria and viruses to infect a bird more easily.
Keep in mind that if you practice all the procedures, you may still see a sick bird at your feeder. Salmonellosis is the most commonly spread disease at feeders and can kill birds quickly. Infected birds spread the bacteria in their droppings.
There are other diseases that affect birds typically using feeders.
Trichomoniasis is caused by a one-celled protozoan parasite. Mourning doves are particularly susceptible. The disease spreads when sick birds drop contaminated food or water at a feeder or watering area.
Aspergillosis is a mold that grows on damp feed and in the debris beneath feeders. Birds inhale the mold spores, and infection spreads in the lungs, causing bronchitis and pneumonia.
Avian pox is a virus that causes wart-like growths on featherless surfaces of a bird's face, feet, legs or wings. The virus spreads by direct contact, by insects or by viruses shed on food by infected birds.
Avian influenza, or the H5N1 virus, has been in the news. This disease has infected poultry, and although one strain is known to infect humans, most strains do not.
"Remember, a sick bird is not necessarily your fault," says Sanchez. "Birds die of natural causes all the time. We just tend to see them more when we feed them."
Judy Scott writes on garden topics for the Oregon State University Extension Service.