There are usually a couple of Goldfinches which insist in eating upside-down. I think they found that they don't get involved in squabbles quite so often when they avoid the perches.
I had temporarily taken down one of the feeders while I was cutting down the Sunflower. By the lunch time rush I had forgotten to put it back up so there were six perches less than normal and a sudden influx of House Sparrows.
Have a great weekend everyone.