Yup, it was Jazzerkins and I who had thought we had seen somebirdy on West Radisson. I think J said it was early morning on ledge next to the nestbox. It was later in the morning when I spied what looked to be a smallish bird (ie not as big as Sandy) almost exactly in the middle of the ledge where the nest box is situated, tail hanging over the edge (so not facing out) but not a really dark bird either. Of course with the naked eye, in dull light, colour can play tricks, but I'd say there was definitely a bird there.