A good session this morning resulting in a couple of interesting birds. A total of seven Bullfinches (2 ads, 5 juvs) were caught including this male, easily aged as a 3JP!
http://www.britishringers.co.uk/blog/#January%202010 where they make reference to "Ageing and Sexing in the European Treecreeper" by Suorsa and Hakkarainen. This study also mentions a contrast in the colour of the alula feathers in juveniles. I didn't detect this in the hand and I don't think the photos are conclusive either.