There seems to be a conclusion forming that the departure of the thrushes and bluetails means they must have moved north due to warm weather. Is it not feasible that they have actually moved south following the passage of the cold front from 8th-10th? It seems illogical that they decide a drop in temperatures should be a trigger to move north. The cold front also resulted in the arrival of large numbers of Tristram's Buntings into Hong Kong over CNY. Again, it seems odd that these should have moved south out of China while the thrushes and bluetails moved back north into China.
