Today on the HKWildlife.net.forum there are images from more than one photographer of at least seven Russet Sparrows together. I presume these were taken at Long Valley today. See
http://www.hkwildlife.net/index.php?styleid=17
I mention this because:
i) no images of these birds have appeared on this, the HKBWS website, so they might go unnoticed by interested parties
ii) this species was recently placed in Category III i.e all records are now deemed to refer to escaped/released birds
To me, the birds in the photos look in pristine condition and - although I understand the problems of defining the true status of this species in HK - I can't really see why these birds should not be considered genuine migrants.
David