When the liquid in your feeder starts turning cloudy, that's bacteria growing, and it's time to clean and refill the feeder. Prevent contamination and mold by giving your feeder a good scrubbing with a mixture of vinegar and water. A bottlebrush and a pipe cleaner can help you get those hard to reach places and clean out the feeding ports.
"This juvenile male had mold on its chin, perhaps from a dirty feeder. Mold is a big problem for hummingbirds. If the mold gets wrapped around the hummingbird's bill, it cannot open its bill and, thus, starves to death. Please keep your feeders clean."
Deborah Repasz