The image below of a male Reed Bunting was taken yesterday by Basil Thornton and shows that the way that birds get their 'smart' summer plumage is not quite as you may expect. The lovely neat browns of the winter plumage actually wear away to produce the mat black of the summer head on this bird. You can actually see where this has started to happen around the eyes and the plumage now look all flat and one colour. I think that may have simplified it a bit but I think you get the idea!