I fead a pair of hummers all winter and then found one of them dead on my deck, the second one was around for awhile and then it disappeared also. I clean and refill my feeders regularly and have been for over 40 years so I couldn't figure out what happened. I kept 2 feeders up and filled for over a week before I noticed two new hummers and they only came about every third day for short sip and off they went. They are now feeding everyday and one is taking baths in fountain by one of the feeders. Keep feeders clean and filled and they will come back.