Thank you for the additional photo. The rung number starts with AB, but this will not help to work out which individual this is. Several birds ringed over the last year or two will have these letters. If you have any photos showing the bird from a different angle, this may help.
As Mathew mentioned, one of the main aims of these rings is to study migratory movements, but they can also tell us more about how long the birds live and how long they stay in Mai Po. It is almost certain that the Cinereous Tit was ringed in Mai Po, and probably also the Black-faced Bunting.
