Grackle problems here, too. Other years, in a different location, they had moved on by now, but seem to be staying this year. Still hoping they will leave, I have gone to inexpensive tube feeders (3.50 at my local dollar store) that they can't perch on as a, hopefully, only temporary fix till they do go as cardinals, blue jays and mourning doves cannot perch either. My HUGE problem is suet. I have my feeders fastened to trees and the woodies really like it that way but the grackles have learned to cling to the bark just like the woodies, so only having the bottom open does not work. Tried it. Any ideas? Must I go to hanging the suet cages? Really don't want to if I don't have to.