The Coal Tits were bolder, flying in up to four at a time even when others were feeding there (it's a big feeder). Note the deformed left foot and stubby tail on the one with his head in the feeder. I called him/her Stumpy. I'll show more images of him/her later, both from that day and from a later visit. Its tail seemed to have grown a bit when I was there again the next weekend, but that deformed foot was the same.