Vietnam - Part 2 - One more warbler (1 Viewer)

[Fwin71]

Bird 3: Pic 6, 7 and 8. We had trouble with this bird that we first identified as an eastern crowned warbler but it has pale legs and the bars and supercilium are too marked so we now think it could be a Claudia's leaf warbler (excluding Kloss's because of the undertail which isn't white). We saw this one in Cuc Phuong national park, 3h south of Hanoi (Northern Vietnam).

 

[andyb39]

It could be Claudia's, but I think we also have to consider Hartert's, although it doesn't look bright enough, and Blyth's, if it occurs there (not sure if it does or not). I've lent my Lynx guide out, so can't check distribution there.

I don't believe Kloss's has a white undertail, by the way - perhaps you're thinking of Davison's/White-tailed? If you look at this image, you'll see the undertail is quite dark but with white edges (2nd image): https://ebird.org/species/klolew1?siteLanguage=pt_PT. I don't believe it's found there though.

 

[johnallcock]

It could be Claudia's, but I think we also have to consider Hartert's, although it doesn't look bright enough, and Blyth's, if it occurs there (not sure if it does or not). I've lent my Lynx guide out, so can't check distribution there.

It's not bright enough for goodsoni, but it could be fokiensis Hartert's. At the moment I don't think we know enough about ID of these to say which of the three species is most likely.

I don't believe Kloss's has a white undertail, by the way - perhaps you're thinking of Davison's/White-tailed? If you look at this image, you'll see the undertail is quite dark but with white edges (2nd image): https://ebird.org/species/klolew1?siteLanguage=pt_PT. I don't believe it's found there though.

Kloss's breeding in China could probably turn up in winter I guess. Again, I don't think we really know enough about the movements. But I don't think this bird is Kloss's, which should seem small and small-billed, approaching Pallas's in structure.

 

[Fwin71]

Here are the maps for those species in the Lynx.

Kloss has variable white on the outertail feathers while there is none. Plus, it isn't as yellow (although the disturbans wintering in North Vietnam is quite dull) and for us it looks like a bigger warbler than Kloss's.
Could be Hartert's or Blyth's indeed but it isn't supposed to be in north-eastern Vietnam

 

[johnallcock]

Here are the maps for those species in the Lynx.

Kloss has variable white on the outertail feathers while there is none. Plus, it isn't as yellow (although the disturbans wintering in North Vietnam is quite dull) and for us it looks like a bigger warbler than Kloss's.
Could be Hartert's or Blyth's indeed but it isn't supposed to be in north-eastern Vietnam

I wouldn't trust range maps for any of these species, especially in winter. ID features are not known so species could be overlooked outside the published ranges, even if they actually occur commonly. Similar problems have occurred with other species complexes (eg 'Arctic' warblers, 'Pale-legged' Leaf Warblers), where the actual ranges are still not clear.

 

[andyb39]

According to both the Lynx guide and HBW, Blyth's is an altitudinal migrant and is only present in NW Vietnam (I know they're there as I've seen a couple at Sapa). Therefore it seems unlikely at Cuc Phuong.

Claudia's certainly does occur at CP - if Macaulay wasn't down, like OBI (for a couple of weeks now!), I could link the photos taken by a friend of a bird he saw there, which has been identified by the Thai crew as Claudia's.

Is it just me, or does Hartert's have a slightly downcurved bill (a slight hook)? This is one image from Wushiyan - I'm not sure which race this is, but the bill shape is distinctive: https://zootherabirding.blogspot.com/2012/05/wuyishan.html

I noticed the same feature in the bird in the attached photos, photographed at Dalat and identified as Kloss's. Could this bird be Hartert's? I don't see the same bill shape in Fwin's bird.

 

[johnallcock]

My main concern is that I find that many of the conclusions about separation of Blyth's, Claudia's and Hartert's are based on observations in the wintering ranges, following assumptions about the species present. They have not been tested on birds that are identified by DNA or song (which is the basis of the split), and they have not been tested on the breeding grounds.

Even on the breeding grounds, I think that there is a lot of work needed. It's generally assumed that birds in a certain mountain range are a certain taxon but in fact there may be more than one taxon on the same mountain, perhaps separated altitudinally (I have observed this in China, birds with different songs at different altitudes). This complex is a long way from being resolved, and trying to put an ID on every bird based on incomplete information could make the situation worse.


Blyth's ticehursti and Hartert's fokiensis breed in the mountains of China and must move south in winter. Blyth's ticehursti also breeds into SE Asia and I find it improbable that migrant ticehursti would all migrate into the breeding range of the resident birds. So where do these migrants go? They seem not to get reported - most reports in SE Asia seem to be of migrant Claudia's or resident Blyth's.

Just to throw more confusion into this, the problem extends also to other species, especially Emei LW. This is very rarely reported away from breeding grounds. Where does it go? In fact, looking back at the bird in the original post, I'm not sure I could rule out Emei LW as an ID.

 

[andyb39]

Images on eBird/Macaulay are now displaying again, so I'm sharing the link to a friend's checklist from Cuc Phuong that I mentioned earlier, with a collection of images of Claudia's. They often seem to look like this - rather dull without much yellow in the plumage, with a whitish crown-stripe and cream supercilium and wingbars, and a little greyish around the head. I don't think this bird can be Hartert's - it's just too dull - and behaviour seems to rule out Blyth's. It's rather duller than the OP bird too.

https://ebird.org/checklist/S41101577

Re the OP bird, having looked at a few images of Emei online, I'm not sure I could rule it out either.

 

[johnallcock]

Images on eBird/Macaulay are now displaying again, so I'm sharing the link to a friend's checklist from Cuc Phuong that I mentioned earlier, with a collection of images of Claudia's. They often seem to look like this - rather dull without much yellow in the plumage, with a whitish crown-stripe and cream supercilium and wingbars, and a little greyish around the head. I don't think this bird can be Hartert's - it's just too dull - and behaviour seems to rule out Blyth's. It's rather duller than the OP bird too.

https://ebird.org/checklist/S41101577

Too dull for goodsoni, certainly. But is it too dull for fokiensis?

How does the behaviour rule out Blyth's? I've never heard of there being a difference in behaviour before, so not disagreeing, but it may be something useful to look for if true.

we've had more birds lacking yellow tones than usual in Hong Kong this winter. I'm still trying to work out what that means and looking to learn from discussion like this. Are these fokiensis or claudiae or something else?
Only goodsoni is currently on the HK list because of the difficulties of ID, but I've heard birds with non-goodsoni song in the past.

 

[andyb39]

Thanks for your input, John.

I've been having a look at images of both Hartert's and Claudia's on IBC. I would say that even fokiensis is noticeably brighter than Claudia's, even if the images of the latter show birds in fresh plumage. The supercilium on fokiensis[/I seems to be consistently yellower, as do the wingbars and perhaps the crown-stripe too. The rest of the plumage on fokiensis seems to be a more vivid green, with no grey tones around the head and nape. Bill shape is actually very similar, that of Claudia's slightly blunter-tipped.

Overall I would stick to my opinion that Tommy Pedersen's bird is too dull for Hartert's of either race.

Re behaviour, Claudia's (and Hartert's too, apparently) behaves in a distinctive way, spending a lot of time creeping along branches, hanging off creepers, turning upside down and clinging to the trunk. Blyth's, as per Ayuwat, does do some of these things but only momentarily - for example, I saw one at Sapa clinging to a tree trunk, but only for a second, so I would say if a bird is behaving like this in a prolonged fashion, it shouldn't be Blyth's. Birds around Dalat seem to behave slightly differently, behaving a bit more like a Nuthatch. I observed this behaviour in winter, so you might think these birds could have been Claudia's instead, but at the time I remember hearing their calls and even some song and matching the vocalisations to recordings on XenoCanto. This may be adaptive behaviour and it is a disjunct population.

Also, Tommy's bird looks very like a bird I saw at Hoi An (another lowland location) in the winter of 2015, which was behaving in exactly the same way. I couldn't see any yellow tones on it at all. I think we discussed this bird here before. It's my little theory that Claudia's prefers lower elevations on its wintering grounds, but maybe I'm assuming too much.

Are there any images of these dull Hong Kong birds available?