A lot of Yellow-bellied Prinias are trapped and ringed in Hong Kong, especially at Mai Po (57 ringed and 28 retrapped there in 2007). Unfortunately there is not quite enough visible on this ring to work out which individual this is.
It is useful to receive resightings of ringed birds where the ring number can be read, as these help us to understand the movements of Hong Kong birds. A good example was the Japanese Yellow Bunting photographed last autumn, for which we were able to track down details of when/where the bird was ringed (see http://www.hkbws.org.hk/phpBB2/viewtopic.php?t=3772).
Preferably the whole ring number (usually 6 or 7 letters/numbers) should be visible, although for some less-common species it may be possible to recognise the individual from an incomplete number.