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        Discussion Area 討論區 >> Bird Identification 鳥類辨識 >>  Not Manchurian Bush Warbler. Should be Aberrant BW
        
(Message started by: HF_Cheung on Jun 8^th, 2006, 11:37am)

Title: Not Manchurian Bush Warbler. Should be Aberrant BW
Post by HF_Cheung on Jun 8^th, 2006, 11:37am

The former "Chinese Bush Warbler" on the HK list has been split into two species:  Manchurian Bush Warbler and Japanese Bush Warbler.  The one in HK is now Japanese Bush Warbler, which consists of two subspecies, one breeds in Japan and one breeds in NE China.  Manchurian Bush Warbler breeds in Central China.  The following photos is of the same bird, taken in Sichuan Wawushan in 9 May 2006.  The call of song of this bird is totally different to that of Japanese Bush Warbler.  Other than that, there seem to be no concrete ways to separate them, at least not yet.  May be some of our members can help finding out the good field marks.
http://www.geocities.com/aphfcheung/IMG_7154P.jpg
http://www.geocities.com/aphfcheung/IMG_7155P.jpg
HF Cheung

Title: Re: Manchurian Bush Warbler
Post by Michael_Leven on Jun 14^th, 2006, 4:06pm

I think that the bird in the photos is an Aberrant Bush Warbler C. flavolivacea. This is not a species which has any very obvious fieldmarks and the picture in Mackinnon and Phillips is not helpful. I identify this species more on overall jizz - it always appears to show (as in these photos) a rather scruffy, dishevelled tail; and negative features - no obvious rufous tones, little contrast between upperparts and underparts, generally olive tones. However, the song is a highly distinctive tri-syllabic whistle very unlike diphone/canturians.

I just returned from Wawushan where this species was abundant in the bamboo on the summit. As far as I know C. canturians/diphone does not occur there.

I agree with Ho-fai that there is probably more than one species involved in the diphone/canturians complex, but I think that the situation is more complex - the problem is how many species and how to split the seven races.

Note that Dickinson in the Third Edition of the Howard and Moore Checklist states: "...it is very probable that diphone consists of two or even three species and King and Dickinson (1975) separated canturians from diphone, but no detailed explanation has been published. Dickinson et al. (1991) reverted to one broad species, which we follow here, but we recommend further study."

The small olive forms (diphone which I have seen on Honshu and (presumably) the other Japanese island forms) do seem a likely split from the mainland forms.

However, the remaining question is whether there should be a split between the northeast Asia breeding forms (borealis and sakhalinensis) and the central China canturians (which I just found singing in May this year at sea level in reedbed near Shanghai). Any of these three forms are migrants and could occur in HK in winter but there seem to be no published differences in plumage or measurements. However, song could be different and perhaps habitat preferences - are our wintering reedbed birds the same as the upland shrubland birds?

Like Ho-fai I think that more work is needed - good photos and taperecordings as well as trapping and DNA analysis.

Best regards

Mike Leven

Title: Re: Manchurian Bush Warbler
Post by HF_Cheung on Jun 15^th, 2006, 10:39am

Thanks Mike,

I have checked this bird against the Oriental Bird Club image.

http://www.orientalbirdimages.org/search.php?action=searchresult&Bird_ID=1873

There seems to be significant differences in colour between this bird and the images posted there. I am very puzzled when you say there are no clear rufous tone to this bird, while I can see very clear rufous tone on the crown, especially the forecrown.

I have recorded the call and I will check it when I have the chance again. I remember last time I check, it fit the call and song description in Machinnon well. I will ask Forrest how I can post the sound file.

Thanks for the opinion. I hope we can review more difficult bird species in China.

HF Cheung

Title: Re: Manchurian Bush Warbler
Post by miket on Jun 17^th, 2006, 5:25pm

It should be noted that the Aberrant Bush Warbler on the OB images database is of the race weberi, sometimes referred to as Manipur Aberrant Bush Warbler, which is very different in appearance from the birds in China, but which sounds, to human ears, to have the same song, and which even responds to tape playback of Chinese birds, suggesting that, despite appearances, there are no grounds for splitting it.

Having said that I'm not sure what the bird in HF's picture is, but have to agree with him that, on my screen at least, it does show clear rufous tones.

Mike Turnbull.

Title: Re: Not Manchurian Bush Warbler. Should be Aberren
Post by HF_Cheung on Jun 18^th, 2006, 11:11am

Thanks Mike Turnbull and Mike Leven,

I have checked the sound recording already, and it so fit Aberrant Bush Warbler better.  The illustration in Craig Robson "A field guide to the birds of SE Asia" is good for this species"  On the OBC Image Gallery, John Holmes photo in Mynamar (Photo no. 3) is also this species.

So it leave a question of whether there is a good photo of Manchurian Bush Warbler, and what are the good field marks.

Any interest in starting a new discussion area on the difficult birds of China?

HF Cheung

Title: Re: Not Manchurian Bush Warbler. Should be Aberran
Post by Michael_Leven on Jun 19^th, 2006, 5:02pm

I'm glad that we agree. I probably confused the issue by writing "no obvious rufous tones" - better wording would have been "crown and wings no so obviously rufous as on Manchurian".

However, Ho-fais's original point is still valid - how to separate canturians from borealis/sakhalinensis and which form(s) occur in HK? As I said before, the singing birds that I saw near Shanghai (which should, on range, be canturians seemed in the field like HK birds (see, for example Peter and Michelle Wong's excellent photos on OBC).

However, how these differ from the northern forms I don't know (the only OBC photo which might be one of these is a presumably passage bird from either Beidahe or Happy Island.

I like the idea of a discussion forum on the difficult birds of China - as well as ID issues this could cover priorities for photos and sound recordings as well as issues like those species that no one seems to see (like Biet's Laughingthrush and Przewalski's Parrotbill - Mackinnnon and Phillipps call them White-speckled Laughingthrush and Rusty-throated Parrotbill).

Best regards

Mike Leven