When first set up, the feeders attracted Goldfinches by the dozen, feeding and fighting each other. The Robin kept out of harm's way and foraged for odd bits of food dropped on the ground. Recently though, the Robin has plucked up courage and started perching on the feeder itself, ignored by the finches, who in between brief spells of feeding, devote their energies solely to attacking each other.
There may be more than one Robin hereabouts, but I never see more than one at a time.
Through window glass. Thank you for your comments, and good birding!
John