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By  Laura Ball

January 1, 2017 (La Mesa/Mt. Helix) -- I have very active hummingbird feeders and have noticed a few birds with tumors on their beaks (see photo). I have been in contact with a specialist at the University of California-Davis Vet Med Center about this, and she had some suggestions on how to help them. The hummingbirds probably have avian pox, which is contagious - to birds only, not humans - and can spread through the feeders we all have in our yards.

Sadly, this disease is usually fatal to the birds, so to minimize the spread of the disease, the feeders need to be cleaned every day when it is hot, and every other day in cooler weather (instructions below). If you can’t manage that, and I know it’s a chore, because I do it, simply take your feeder down. Any black mold or fungus of any kind needs to be fully cleaned or you are doing more harm than good to the little guys. We have a lot of flowers in our yards, so they will manage. Please share this - pass it on to anyone who might use the information.

BEST WAY TO CLEAN: use hydrogen peroxide. It works especially well if you soak the yellow flowers from the feeder to get rid of the black mold. Use bottle brushes to clean out all of the openings. Have two sets of feeders & clean and air out one set then swap them…do every day.


  • The best solution is to have natural food sources (flowering plants) in the yard. Plants that attract both hummingbirds and butterflies include butterfly bush, lavender, fuschia daylily and pentas.  Hedge options include jasmine and honeysuckle.
  • Have enough clean feeders to support the current hummingbird population in your yard - cut down on fighting at the feeder
  • Put multiple feeders in one area
  • Bleach can remain in the plastic on the feeder - if you use it, rinse very well and then air out the feeder before re-use. Soap leaves a residue, so avoid using soap or detergent
  • If you have black fungus - get rid of the feeder if you can’t clean it completely
  • Take off the bee guards; you can’t clean it with those in the way, and mold and fungus build up in that area.
  • Use glass vessels instead of plastic
  • Buy feeders with a wider mouth that a bottle brush will fit in, so you can fully clean them
  • Change out or clean the feeder each day to cut down on transmission of the disease
  • Sugar water goes bad quickly, fermenting in as little as 24 hours in the heat, so change it daily.

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Avian Pox

Hi, I was wondering if you learned any more about hummingbirds with avian pox? I just had my 5th migrator with pox arrive in my yard. So afraid of this spreading to my resident hummingbirds. Thank you!!