As Koel says, there is uncertainty in identifying 'female-type' (i.e. including some first-summer males) Green-backed Flycatchers as either Green-backed (elisae) or Narcissus (owstoni).
None of the records of female-type Green-backed since 2005 have been accepted to species. There have been five, including this one, three in spring and two in autumn. So it's possible the spring ones are owstoni (which winter in Philippines) and the autumn ones are Green-backed (which winter in SE Asia). All the accepted male owstoni (four since the first in 2002) have been in spring. There haven't been any male Green-backed since the late 90's (although the two accepted records from 1996 and 1997 were spring, so that's a bit confusing).
There are other factors. The Philippines is so large and underwatched, we don't know for sure which species winter there and the populations of elisae and owstoni is small.
I prefer to use nominate Narcissus and Yellow-rumped as examples. These are annual spring and autumn migrants respectively in Hong Kong and are known to winter fairly exclusively in Philippines and SE Asia respectively. But even then, we get the occasional ones in the 'wrong' season.
[ Last edited by wgeoff at 23/10/2011 09:00 ]
