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-   -   Phylloscopus, Khao Lak, TH (https://www.birdforum.net/showthread.php?t=358962)

nikothomsen Saturday 24th March 2018 10:17

Phylloscopus, Khao Lak, TH
 
2 Attachment(s)
Hi guys,

I shot this bird December 2016 in Khao Lak, Thailand. I originally logged it as Pale Legged Leaf Warbler, but I am starting to doubt. Was not heard.

Grahame Walbridge Saturday 24th March 2018 15:45

You were right to doubt your original id Nick, PLLW/SLW has a pink-based lower mandible which is noticeably darker distally. Judging by the brownish wash on breast sides and flanks it looks like one of the 'Arctic' complex, most likely borealis given date and location.

Bryon Wright Sunday 25th March 2018 17:23

Hi all,
one to ear-mark and seek opinions from people familiar with Japanese-Leaf warbler. Borealis invariably shows a dark horn, distal tip, on the lower mandible. The silvery, white underparts are not dissimilar to eastern-crowned are typical for JLW as well. Think the visible part yellow suffusion, is not a reflection but this is so difficult to see in the field. Grey contour feathers show through in moulting december birds from all of this group.

Grahame Walbridge Sunday 25th March 2018 19:18

Quote:

Originally Posted by Bryon Wright (Post 3695783)
Hi all,
one to ear-mark and seek opinions from people familiar with Japanese-Leaf warbler. Borealis invariably shows a dark horn, distal tip, on the lower mandible. The silvery, white underparts are not dissimilar to eastern-crowned are typical for JLW as well. Think the visible part yellow suffusion, is not a reflection but this is so difficult to see in the field. Grey contour feathers show through in moulting december birds from all of this group.

Where on earth do get your information from Bryon? Not that I agree the OP bird has silvery white underparts, but where did you get the idea this is a feature in any way associated with JLW? Xanthodryas is known to be on average the brightest within the 'Arctic' complex with generally brighter green upper parts and with more extensive yellow suffusion to the supercilium, face and underparts. http://orientalbirdimages.org/search..._ID=&Location= The OP bird shows no sign of active moult and neither should it do so as early as Dec. And as for the bill pattern, its more variable than generally perceived, which is clearly evident if you look at enough images. A bird with a poorly marked lower mandible here http://orientalbirdimages.org/search..._ID=&Location= to a bird with a darker bill here suggesting LBLW here http://orientalbirdimages.org/search.php?
Bird_Image_ID=137922&Bird_ID=1808&Bird_Family_ID=& Location=
A typical borealis lies somewhere between the two, on that we can agree, but all birds aren't typical.


Grahame

johnallcock Monday 26th March 2018 04:14

My impression of this bird, based largely on the extent of pale on the lower mandible, was more of a Two-barred/Greenish Warbler than an Arctic-type. But based on these two images alone, I personally would suggest it's best left unidentified.

Grahame Walbridge Monday 26th March 2018 06:16

Quote:

Originally Posted by johnallcock (Post 3696063)
My impression of this bird, based largely on the extent of pale on the lower mandible, was more of a Two-barred/Greenish Warbler than an Arctic-type. But based on these two images alone, I personally would suggest it's best left unidentified.

I had considered TBW due to the unmarked lower mandible but dismissed that option because of the combination of clear olive-brown suffusion to breast sides/flanks and yellowish toes and tarsus. I think the location is a also more indicative of AW. A very similar bird herehttp://northernrustic.blogspot.co.uk...-thailand.html However, I can fully understand your your final comment.

Grahame

andyb39 Monday 26th March 2018 06:41

An interesting blog post here showing a probable xanthodryas with several borealis individuals. Note the yellowish wash on the underparts and yellow ear-coverts, neither of which the OP bird shows.

https://digdeep1962.wordpress.com/20...ctic-warblers/

nikothomsen Monday 26th March 2018 07:29

That was a lot of information, but thank you for all your responses. I assume borealis/xanthodyras/examinandrus is as far as we're getting to an ID here?

andyb39 Monday 26th March 2018 13:32

I was trying to say that I don't think it's xanthodryas as suggested. Examinandus also seems unlikely, as it apparently has an extensive dark tip to the lower mandible.

https://birdingbeijing.com/2012/05/1...-leaf-warbler/

http://bangkokcitybirding.blogspot.a...in-autumn.html

gandytron Monday 26th March 2018 14:50

Only one confirmed record of Japanese Leaf Warbler in Thailand (trapped on Koh Man Nai in April a few years ago, confirmed by DNA).

I would leave the OP bird unidentified, but don’t see any Japanese in it.

Bryon Wright Monday 2nd April 2018 14:29

Hi all,
there have been one or two postings on the bill colour of Arctic on bird forum which have proved useful.
Was ear-marking this has something that should be shown around not specifically identifying it as such.
Think one would be hard pressed to find a photograph or even a written description of a known borealis without the tell-tale really pronounced, dark bill tip. The examples given are not IMO proven, borealis. John seems to find the OP as having an unmarked bill. Also yellow as is possibly present on the OP.l Do not think many will disagree that the moult of borealis, late July( suspended) and then sometimes as late as April, with the body moult mainly in Dec/Jan! Some may find the underpart colour of borealis noticeably different from all the others during this period. At least this can be tested in the field. Personally this why I believe the other posters have veered off towards TBW and PLW!

Grahame Walbridge Monday 2nd April 2018 16:09

Quote:

Originally Posted by Bryon Wright (Post 3699433)
Hi all,
there have been one or two postings on the bill colour of Arctic on bird forum which have proved useful.
Was ear-marking this has something that should be shown around not specifically identifying it as such.
Think one would be hard pressed to find a photograph or even a written description of a known borealis without the tell-tale really pronounced, dark bill tip. The examples given are not IMO proven, borealis. John seems to find the OP as having an unmarked bill. Also yellow as is possibly present on the OP.l Do not think many will disagree that the moult of borealis, late July( suspended) and then sometimes as late as April, with the body moult mainly in Dec/Jan! Some may find the underpart colour of borealis noticeably different from all the others during this period. At least this can be tested in the field. Personally this why I believe the other posters have veered off towards TBW and PLW!

Firstly, regarding borealis moult timing, you clearly didn't read post 4. All age classes undergo a head/body moult and including some retrices post breeding and prior to autumn migration. A complete pre-breeding moult takes place on winter-quarters (BWP). And this is what Wells has to say: MOULT All age/sex classes moult head/body and some tail-feathers prior to arrival (BWP). No further moult has been reported among autumn passage migrants or in early winterers but, apparently all age classes moult again (fully?) in late winter. Primaries are replaced regular-descendently, and intensively (with up to 5 inner feathers in overlapping growth) as early as February. Most February-and all of March-dated birds handled were in moult, wing moult completing between mid-March and early April (p8-9, 9 or 8-10 on 1 April). T1 drops coincident with p6 or 7 and tail-moult at this season can also be intense (most feathers overlapping growth on 15 March:ZRC-NUS) to finish coincident with p10. Body moult continues longer with latest record (light moult of underparts) on 1 May (UMBRP)

So, they do not undergo a body moult as early as Dec/Jan-perhaps you'd care to provide a reference?

I sent the images to Phil Round and this is his reply:

The default arboreal Phyllosc in S Thailand, once you have excluded YBW and ECLW, especially in coastal woodland and mangroves, would have to be Arctic. I have little doubt that is what this is.

Phil

I have just contacted Phil to ask whether or not borealis can show a completely pale lower mandible i.e, lack a distal dark spot, and he came back to me with an image illustrating this within a matter of minutes! And before you ask, it was trapped and confirmed as borealis (wing 61.5 & short p1: 2.3 <pc) including a sound recording, which 100% eliminates Kamchatka.

Grahame

P.S I would post the image if it were mine and if I knew how....you will just have to take my word for it. It seems they may not be that unusual.

Bryon Wright Monday 2nd April 2018 16:52

Grahame,
Are you saying a borealis never moults in December? You can see the contour feathers breaking up on the throat and upper breast, next to what you describe as a olive-brown breast suffusion. Surely no one can see an olive-brown suffusion on OP bird as you describe? The down feathers are a shade of mid- grey when contours are moulted as you can see in the OP?

Grahame Walbridge Monday 2nd April 2018 17:31

Quote:

Originally Posted by Bryon Wright (Post 3699497)
Grahame,
Are you saying a borealis never moults in December? You can see the contour feathers breaking up on the throat and upper breast, next to what you describe as a olive-brown breast suffusion. Surely no one can see an olive-brown suffusion on OP bird as you describe? The down feathers are a shade of mid- grey when contours are moulted as you can see in the OP?

I am not aware of any literature that records any moult as early as December nor do I see any definite sign of moult in the OP. The grey-gown/olive-brown breast sides are typical of Arctic.

More here from PDR on moult:
Complete moult late winter, as is well known. I have seen Arctic Warblers in moult from about mid-Feb onwards. The only moult-cards I have (birds handled during my own work) are from 7 March onwards (coinciding with my earliest Man Nai captures), with primary moult score of c. 28 already and earliest more or less complete moult (moult score 50) by 30 March.

I'll ask you again-where is your evidence? I have provided references, including from individuals who regularly handle the species, so why don't you?

Your frequent 'hi-jacking' of threads is becoming tiresome.

Grahame

Bryon Wright Monday 2nd April 2018 20:13

Grahame,
why the splenic tantrum? If PR has not handled a December bird he is not able to report on its moult? You are revising the colours that you described originally in your post now as well. I gave empirical information that people can try out in the field in Thailand and then either reject or accept it. If it so important for you to be correct then have it with pleasure!


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