[Hong Kong] ID please

This is definitly a very interesting bird by many aspect which picked up the attention of many of us.
I think it would be great to post more pictures of it if there is any, as this is far to be a straightforward ID.
Picture showing better the undertail coverts and the tertial pattern would be of great help I think...


Frankly the more I looked into this bird, the more I believed that this is an adult or a 2nd Year Saker Falcon....
There is a very large panel of features pointing out to this species to me :
- the head pattern is just a perfect match
- the barring on the rectrices reduced in the central pair
- the small spot at the base of primaries on the outer vexil
- the underwing pattern, I can't find any picture of a Peregrine showing such a contrast between (underwing)covert, the lesser and median covert are almost unbarred  and heavily contrasting with the greater with dark brown barring...This is again really pro-feature for Saker...

Then the overall color of the bird, the rufous fringed lesser and median covert (upperwing) contrasting with greater covert and primaries/secondaries...

Happy to hear what other think, I think the key point is to age it properly...


to me there are really many features pointing out to Saker.

- the tail projection to me exclude Barbary Falcon, wing tip fall at tail tip in most pictures on OBI for Barbary and it is clearly not the case on this bird.
Other features to me that is wrong for a juvenil Barbary (as I see no point comparing this bird with an Adult Barbary) is the underpart background which is clearly of-white, and should be more warm on a Barbary, the dark marking seems also very bold to me.

- to me the most likely confusion would be with a juv Peregrine. The question is it possible for a juv Peregrine to show such a head pattern, with so poor moustaches, so poorly barred undertail coverts.

To me there is many more features matching an adult Altai Falcon a suggested split from Saker in Birds Of Central Asia which is giving a description that to me is clearly ressembling this bird. A male would explain its small size then...

I think pictures of thisbirds should be sent to people used to deal with these taxa.

Very nice set of pictures and very well documented sighting...Hopefully its ID will be sorted out.