This is difficult! I have done some more research and still have not reached a firm conclusion though still tend towards Verditer for the reasons discussed below:
First of all, I echo Mike T's suggestion that we may be looking at more than one species in the Pale Blue Flycatcher complex. The three taxa: nominate with an Indo-Himalayan distribution (which is the possible one in HK); diaoluoensis, endemic to Hainan and harterti in SE Asia, turn out to be very different. All the descriptions I have read (Rassmussen, Robson, HBW) seem to ignore this (reasonably in Rassmussen's case as she has only one taxon to feal with). Based on very few photos (one in HBW and eight on OBI), I have some tentative suggestions about separating these (males), as follows:
harterti seems to be very distinct (and has to be a possible split), with not just a large bill, but a distinctly hooked upper mandible, buffy undertail coverts with no pale tips giving a barred appearance and (usually at least) very turquoise tones echoing Verditer.
diaoluensis seems to be intermediate in bill between harterti and nominate (large but no hook)and based on J&J Holmes photos on OB is a very even blue bird with no turquoise tones.
unicolor (nominate) even blue colour (as dialuoensis) but perhaps lighter, no turquoise, not particularly big billed. Note, though, that there is only one photo on OBI of this taxon. Unfortunately in this photo under tail coverts are completely hidden!
Now, compare the above (and the photos) with Robson's descriptions in Birds of South East Asia (2nd ed. 2002, I have the new one on order!). Here, he describes male nominate (which I agree with Mike T has a number of similarities with the HK bird - though note that he states that this has no turquoise in plumage) but only female harterti (which implies to me that he considers males are not that different): however, I suggest that the photographs tell a different story!
Thus, based on photographs, the HK bird does not match (admittedly, the only) nominate Pale Blue on OBI, but is very similar to a photo of Verditer from Sai Kung on 20 Dec 08 from P&M Wong. It is also quite similar to a 31 May 07 photo from Uttaranchal by Singh (though the latter has darker lores and a smaller bill).
The upshot of the foregoing is:
- I think all published text descriptions are too oversimplified to be of much use;
- I can't find a published photo of the likely taxon of Pale Blue which matches this bird as closely as published photos of the likely taxon of Verditer;
- but, I agree with Mike T that this bird does seem to be big billed and does not quite have the 'feel' of Verditer.
I join the appeal for detailed explanation of where this bird was seen - without further evidence I am not sure that this bird can be identified from a single photo - I would love it to be a Pale Blue and to start off 2010 with a 'Planet Earth Tick'!
Finally, and I confess somewhat mischievously, why is J&J Holmes's photo under Verditer on OBI from TPK in January 2002 not (as likely to be) a Pale Blue?
Happy New Year to all
Mike Leven
