One of my 10 hummingbird feeders is a real nuisance when it comes to cleaning it. It was so stained on the inside of the bottle portion that I could not see through. I had tried everything to clean this feeder/bottle and nothing worked. Today I opened my email and there was the Audubon Society's new citizen science email newsletter, called "American Birds". One of the articles in this online publication was entitled Hummingbirds and Nectar Feeders. The part that particularly interested me read as follows: "Clean the feeders with a solution of one part vinegar to four parts water about once a week. If your feeder has become dirty, try adding some grains of dry rice to the vinegar solution and shake vigorously. The grains act as a good abrasive. Rinse your feeder well with warm water three times before refilling with sugar solution." My feeder was so stained that I used all vinegar and no water. It took about twenty minutes of shaking in total, with several breaks, for the bottle to be cleaned, but it worked like a charm.
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