allwatin

2013-12-01 龍虎山
may be 棕腹大仙鶲 Fujian Niltava, not sure, pls comment. thanks



[ Last edited by allwatin at 1/12/2013 15:53 ]

HFCheung

棕腹大仙鶲 Fujian Niltava
Lower belly and vent paler and more white.

Jonathmartinez

looks like the same Rufous-bellied Niltava taken a few days before, same amount of retained Greater coverts,has irridescence on lesser coverts, the long tail and short PP Paul mention, lack pale base at the lower mandible, just show how variable are the mantle and underpart color appreciation depending on light and angle in my opinion.

tmichael

It definitely IS the same bird - I saw it today.

And, apart from other pretty obvious things like the extensive blue 'cap', as opposed to just a 'peak' on Fujian, it really does have a different jizz from Fujian. I've seen about half a dozen, or maybe more, over 26 years in HK, and though one or two have just been glimpsed and must have some element of doubt, seeing this bird has persuaded me the others were mostly/all Fujian. The wings are shorter and the tail is longer, and the bird seems 'dumpier', more like a  sort of fat Robin-like shape to me.

At least I think so!

Jonathmartinez

agree that there is definitly something with the jizz, and also with the stance, especially with the head that is often more inclined than in Fujian.
This is probably the reason why I found them more easy to ID in the field than on picture.

hmartin

This looks to be an ex-captive bird. This picture was taken yesterday and is of the same individual. Note extensive damage to the longest primary of the left wing. This corresponds to the light area at this position in the original photographs posted by Herman, pictures 2 and 3. Note also primary tip damage to the longest primary of the left wing, in picture 4 of Herman's original post.

[ Last edited by hmartin at 2/12/2013 18:42 ]

tmichael

This is clearly an area in which birds are released, and as such there must be a question mark about its origins, but when birds are as closely scrutinised as in Martin's shot, it makes me wonder how much 'web-splitting' must occur in birds such as this in the normal course of contact with branches etc as they move around and feed. Obviously it'll get repaired periodically, but not immediately, presumably.

I've certainly seen birds undoubtedly wild - I'm thinking of fantails Rhipidura for certain - which have displayed much more incidental tail dishevelment than the flight feathers of this bird show.

And presumably if it's been 'out' long enough to get itself into otherwise tip-top condition - which it surely couldn't be in if it had been in a cage in the last few days - it's had time to preen those wings.

hmartin

Whilst this sort of damage presumably could occur naturally, it's hardly the sort of thing you would like to see on a potential first record of an out of range species.

tmichael

Yeah, basically I agree, it's not ideal, and neither is the location, more significantly. As it got light there on Sunday morning the same trees were full of mesias, some of which looked more than a little bit scruffy to me.

But my main point was; how much web-splitting etc can be seen in birds which are undoubtedly of wild origin, especially when multiple shots are captured with the incredible equipment available today?

hmartin

We are maybe talking at cross purposes here. I'm not referring to "web splitting", but to say a quarter inch of barbs missing from the inner web of the longest primary of the left wing. This feather is partly obscured by the primaries of the right wing in the picture I posted. As such this damage would be visible with any generation of camera, including film cameras.

In 15 years of bird photography I don't have any shots of passerines, that I can think of, that show this level of damage, other than the Autumn Long Valley Japanese Waxwing of many many years ago. This of course was subsequently ruled to be ex-captive. It would be interesting to hear from other photographers about the levels of damage that they have documented in undoubtedly wild birds.

Anyway, ultimately one for the Records Committee to sort out.

[ Last edited by hmartin at 4/12/2013 03:37 ]

HFCheung

I have checked photos on the web.  If the colour of lower belly and vent is not reliable, then may by the easiest field mark is the color of the base of the lower mandible.  Is that right?

HF Cheung

Jonathmartinez

Regarding the dammage to the primary, I think that a 1st winter bird showing primary dammage is less dubious than an adult that has just moulted recently. The dammage is just limited to only one feather, and I would think that dammage on rectrices are more likely the one to be present after a period in a cage rather than a single primary.
Many 1st winter bird at this time of the year are showing less or more strong wear on primary, we're just paying attention on this bird because it is quite a rare one. But the time of the year it appear is quite good and this species range compare to some other birds occuring in Hong Kong makes this species nothing spectacular to occur in HK.

Regarding the features, I think all of them has been said in another post, and the pale base of the lower mandible is at least a solid one only for 1st year birds and has to be confirmed on adult.

ajohn

I would think that damage to primaries is fairly likely in a captive bird, if it flies against the bars of a cage - probably at least as likely as damage to the rectrices (but harder to see in the field). It is also extremely rare in wild birds - while I agree that we are looking particularly closely at this bird, we do also look at other birds (especially when bird ringing) and do not see this sort of damage.

I would also like to point out this picture: http://www.hkbws.org.hk/BBS/view ... &extra=page%3D1 (possibly the only one showing the wing fully extended?) which to my eye seems to suggest that the damage is not restricted to a single primary, but also to other adjacent primaries on the left wing (is the tip missing on the 3rd primary?) and possibly other feathers (there seems to be a gap in the secondaries on the right wing).

I think the most likely explanation for this bird is that the damage has resulted from a period in captivity, rather than the coincidence that a potential first record involves a bird that also shows abnormal plumage damage.