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Warbler ID in National Arboretum, South Korea - August (1 Viewer)
- Thread starter sandwich311
- Start date
Any more images, Rob?
Claudia's would be a vagrant to S Korea and the bill shape (long, strong and slightly hooked) doesn't point to the Blyth's Leaf complex. The impression I'm getting from the head pattern (long, thin supercilium,long flaring eyestripe, dark sides to the crown), bill size and shape and general size and shape is more a member of the Arctic Warbler complex or Eastern Crowned, especially as the P1 (first primary) appears to be short. Pale-legged Leaf Warbler does occur in S Korea but the feet on your bird are yellowish-brown, not whitish pink, and this species has a distinct black frontal portion to the lower mandible of the smaller weaker bill, with a pale tip.
The unmarked orange-yellow mandible on your bird points to Eastern Crowned, although some Arctic can also have one. Eastern Crowned has a yellow vent, which your bird does appear to have, but I'm not sure we can rely on this, as there's also a yellow suffusion on the belly which shouldn't be there in real life. What puts me off is the two rather distinct wingbars - Eastern Crowned doesn't often show much of an upper wingbar, let alone one this distinct. Two-barred is a vagrant and doesn't have such a strong head pattern or strong bill, so my suggestion is ECW for the moment.
Hopefully Grahame or John Allcock will have a look shortly.
Claudia's would be a vagrant to S Korea and the bill shape (long, strong and slightly hooked) doesn't point to the Blyth's Leaf complex. The impression I'm getting from the head pattern (long, thin supercilium,long flaring eyestripe, dark sides to the crown), bill size and shape and general size and shape is more a member of the Arctic Warbler complex or Eastern Crowned, especially as the P1 (first primary) appears to be short. Pale-legged Leaf Warbler does occur in S Korea but the feet on your bird are yellowish-brown, not whitish pink, and this species has a distinct black frontal portion to the lower mandible of the smaller weaker bill, with a pale tip.
The unmarked orange-yellow mandible on your bird points to Eastern Crowned, although some Arctic can also have one. Eastern Crowned has a yellow vent, which your bird does appear to have, but I'm not sure we can rely on this, as there's also a yellow suffusion on the belly which shouldn't be there in real life. What puts me off is the two rather distinct wingbars - Eastern Crowned doesn't often show much of an upper wingbar, let alone one this distinct. Two-barred is a vagrant and doesn't have such a strong head pattern or strong bill, so my suggestion is ECW for the moment.
Hopefully Grahame or John Allcock will have a look shortly.
sandwich311
Well-known member
This is the only picture I'm afraid. Unfortunately it was only there for a split second then flew off.
Thanks for the great detail and information. I really appreciate it.
Thanks for the great detail and information. I really appreciate it.
johnallcock
Well-known member
Hmmm. A tricky angle.
For me, the structure and the head pattern suggest the Arctic complex, as well as the greyish underparts and hint of streaking on the breast. Arctic Warbler usually have a darker tip to the bill, but not all show this, so I don't think this a problem here. The main problem that I can see is in the strength of the wing bars, which look too broad and contrasting for Arctic. Maybe this is due to the angle?
I would expect Eastern Crowned to look cleaner and whiter than this below. I also think they usually look to have a longer bill than this bird and the supercilium usually seems to sweep upwards towards the rear, which is doesn't seem to here (but that's tricky to judge because of the angle). As Andy has mentioned the wing pattern would be unusual for Eastern Crowned.
The wing pattern and pale lower mandible could perhaps suggest Two-barred, but as Andy has already mentioned, the outer primary looks shorter than would be expected. The head and bill structure and head pattern also don't look right for Two-barred to me.
Overall I'd say Arctic complex on this bird, but I could be wrong.
Of course I've been avoiding the question of which species from the Arctic complex. I would expect Japanese to look brighter/yellower than this (and perhaps less likely in Korea), but that's based only on literature not personal experience. I have no idea how to separate Arctic and Kamchatka Warblers from this photo.
For me, the structure and the head pattern suggest the Arctic complex, as well as the greyish underparts and hint of streaking on the breast. Arctic Warbler usually have a darker tip to the bill, but not all show this, so I don't think this a problem here. The main problem that I can see is in the strength of the wing bars, which look too broad and contrasting for Arctic. Maybe this is due to the angle?
I would expect Eastern Crowned to look cleaner and whiter than this below. I also think they usually look to have a longer bill than this bird and the supercilium usually seems to sweep upwards towards the rear, which is doesn't seem to here (but that's tricky to judge because of the angle). As Andy has mentioned the wing pattern would be unusual for Eastern Crowned.
The wing pattern and pale lower mandible could perhaps suggest Two-barred, but as Andy has already mentioned, the outer primary looks shorter than would be expected. The head and bill structure and head pattern also don't look right for Two-barred to me.
Overall I'd say Arctic complex on this bird, but I could be wrong.
Of course I've been avoiding the question of which species from the Arctic complex. I would expect Japanese to look brighter/yellower than this (and perhaps less likely in Korea), but that's based only on literature not personal experience. I have no idea how to separate Arctic and Kamchatka Warblers from this photo.
I have removed what I perceived as a yellowish/greenish colour cast on the photo, and attach the result here.
Obviously, this perception of colour cast is subjective. But, for a few years I have photographed and recorded (because visual separation is difficult or impossible, but voice separation possible) Arctic complex birds on migration in my local spot in central Japan. And the adjustment is based on my judgement of how I need to adjust photos I have taken to reconcile what my eye saw with what my camera produced. My aim in recording was to find a Japanese Leaf Warbler going through the patch, which seemed possible, and which I finally managed last year. Otherwise all the (dozens, maybe hundreds of) birds that were recorded, both on spring migration (mid-June) and in autumn (mid-October) were Kamchatka Leaf Warbler (and Arctic Leaf, borealis, will not be in my area even on a wildly optimistic view). The Japanese Leaf was in mid-May.
If you look at my adjusted photo, you will see that the yellowish vent has gone, but a slight yellow chest wash and the yellow wing tuft remain. Both of these features are common or expected in Kamchatka Leaf in my experience, even though they are hardly shown at all in the illustrated books I have, though they can be seen in some photo books. (The illustrations in Mark Brazil's 'Birds of East Asia' for Arctic complex have been printed with the yellow turned up to 11 in my opinion and experience, and cannot be trusted.)
So, I would go for Arctic complex, probably Kamchatka Leaf (I've never seen Arctic new form, borealis). The lower mandible does look yellow in the photo, but it does often in real life - my experience is that if you look from below you see a black patch in the centre and/or at the tip, but from the side you often don't see it (I think that if you look at my adjusted photo you can see that the lower centre of the lower mandible is darker than the edges, and that if you saw this area from below it would look dark or black).
Apart from other features, the fact that the yellow vent disappears but the yellow chest and tuft stay when adjusted for colour cast point away from Eastern Crowned. As Andy says, the bill is surely too robust for Pale-legged. (However, I have little or no experience of other continental possibilities, so I'm not ruling other things out, if others think they are a good fit.)
Edit: Looking at my own post, I'm not as confident as before that this is not Eastern Crowned. I still think that my adjusted photo has a cream, not yellow vent, and the bill is OK for Kamchatka, and I still think that the yellow tuft which Eastern Crowned also has, wouldn't be so yellow in a photo where the vent had been reduced to cream. But I'm not quite as sure as when I first posted this.
Obviously, this perception of colour cast is subjective. But, for a few years I have photographed and recorded (because visual separation is difficult or impossible, but voice separation possible) Arctic complex birds on migration in my local spot in central Japan. And the adjustment is based on my judgement of how I need to adjust photos I have taken to reconcile what my eye saw with what my camera produced. My aim in recording was to find a Japanese Leaf Warbler going through the patch, which seemed possible, and which I finally managed last year. Otherwise all the (dozens, maybe hundreds of) birds that were recorded, both on spring migration (mid-June) and in autumn (mid-October) were Kamchatka Leaf Warbler (and Arctic Leaf, borealis, will not be in my area even on a wildly optimistic view). The Japanese Leaf was in mid-May.
If you look at my adjusted photo, you will see that the yellowish vent has gone, but a slight yellow chest wash and the yellow wing tuft remain. Both of these features are common or expected in Kamchatka Leaf in my experience, even though they are hardly shown at all in the illustrated books I have, though they can be seen in some photo books. (The illustrations in Mark Brazil's 'Birds of East Asia' for Arctic complex have been printed with the yellow turned up to 11 in my opinion and experience, and cannot be trusted.)
So, I would go for Arctic complex, probably Kamchatka Leaf (I've never seen Arctic new form, borealis). The lower mandible does look yellow in the photo, but it does often in real life - my experience is that if you look from below you see a black patch in the centre and/or at the tip, but from the side you often don't see it (I think that if you look at my adjusted photo you can see that the lower centre of the lower mandible is darker than the edges, and that if you saw this area from below it would look dark or black).
Apart from other features, the fact that the yellow vent disappears but the yellow chest and tuft stay when adjusted for colour cast point away from Eastern Crowned. As Andy says, the bill is surely too robust for Pale-legged. (However, I have little or no experience of other continental possibilities, so I'm not ruling other things out, if others think they are a good fit.)
Edit: Looking at my own post, I'm not as confident as before that this is not Eastern Crowned. I still think that my adjusted photo has a cream, not yellow vent, and the bill is OK for Kamchatka, and I still think that the yellow tuft which Eastern Crowned also has, wouldn't be so yellow in a photo where the vent had been reduced to cream. But I'm not quite as sure as when I first posted this.
Last edited:
Grahame Walbridge
Well-known member
There is absolutely no doubt in my mind that we are dealing with one of the Arctic Warbler complex versus Eastern Crowned which seems to be the concensus. However, as John alludes, this single image from the trickiest of angles makes a firm identification far from straightforward.
Now to address a few of the issues raised. Regarding bill, there is almost total overlap in length between AW (borealis) and ECW, though the latter may average a little longer; Arctic (12.7-15.6) vs ECW (13-16). That said, I would agree with John that Eastern Crowned often appears longer billed in the field, possibly and illusion created by a combination of the bill averaging paler and a subtle differences in structure. KLW averages larger and longer billed (> 16 top end) than AW, while JLW averages heavier billed again. The literature consistently cites a dark tip/distal area to the lower mandible for AW but the reality is, though this might be the most typical pattern, its highly variable; the lower mandible can be unmarked (confirmed in the hand) to all dark, the latter often has dark legs raising potential confusion with Larg-billed Leaf Warbler. Birds like this are known from Alaska
https://macaulaylibrary.org/asset/1...0.1830260848.1610791608-1351674767.1609754812 these breeders formerly treated as a distinct ssp. kennicotti but now subsumed by borealis may account for similar birds encountered within the region on passage/in winter
http://orientalbirdimages.org/search.php?Bird_Image_ID=137922&Bird_ID=1808&Bird_Family_ID=&Location= As for the OP, contra MacNara, it has an unmarked lower mandible, the slight darkening he refers to is clearly not black (or even dusky) IMHO but likely a different tone as illustrated here
http://orientalbirdimages.org/search.php?Bird_Image_ID=124769&Bird_ID=1808&Bird_Family_ID=&Location= That said, I concur with his point made about a small area of black distally at the side of the bill would not always be visible, particularly from below, but that does not apply here.
Assessment of wing-bars from this angle is extremely difficult, but I would take a slight issue with John when he says this pattern, i.e two wing bars, is unusual for ECW. A feature oft quoted in literature when the reality is a significant number exhibit a second, anterior wing bar. Hellstrom refers to it as 'occasional' in his latest offering Ageing and Sexing of Migratory East Asian Passerines. A feature which is clearly visible are the contrasting paler, yellow-green outer margins to the outer greater coverts which is a feature of ECW vs AW where the coverts are uniform in this respect, similarly TBW http://orientalbirdimages.org/search.php?Bird_Image_ID=163779&Bird_ID=1802&Bird_Family_ID=&Location=
The underparts look much better in the lightened image (thanks MacNara) though the yellow patch in the centre of the lower breast is slightly disconcerting; ECW does have pale yellow streaks to the underparts but these would normally be lost in digital images. The under tail coverts do look like they might uniform yellow. https://macaulaylibrary.org/asset/1...0.1830260848.1610791608-1351674767.1609754812 for comparison. MacNara, the yellow 'wing tuft' you refer to belong to the underwing coverts/axillaries, often yellow in Phylloscopus and usually visible, they are actually brighter in ECW than AW.
One final observation, blowing up the image, there appear to be a couple(?) of pale, loose feathers above (and just beyond) the rear end of supercilium, the position equating to roughly where the coronal stripe may terminate, this for comparison. https://macaulaylibrary.org/asset/1...5.1830260848.1610791608-1351674767.1609754812
This is not an easy bird by any means but I am leaning towards Eastern Crowned.
Grahame
Now to address a few of the issues raised. Regarding bill, there is almost total overlap in length between AW (borealis) and ECW, though the latter may average a little longer; Arctic (12.7-15.6) vs ECW (13-16). That said, I would agree with John that Eastern Crowned often appears longer billed in the field, possibly and illusion created by a combination of the bill averaging paler and a subtle differences in structure. KLW averages larger and longer billed (> 16 top end) than AW, while JLW averages heavier billed again. The literature consistently cites a dark tip/distal area to the lower mandible for AW but the reality is, though this might be the most typical pattern, its highly variable; the lower mandible can be unmarked (confirmed in the hand) to all dark, the latter often has dark legs raising potential confusion with Larg-billed Leaf Warbler. Birds like this are known from Alaska
https://macaulaylibrary.org/asset/1...0.1830260848.1610791608-1351674767.1609754812 these breeders formerly treated as a distinct ssp. kennicotti but now subsumed by borealis may account for similar birds encountered within the region on passage/in winter
http://orientalbirdimages.org/search.php?Bird_Image_ID=137922&Bird_ID=1808&Bird_Family_ID=&Location= As for the OP, contra MacNara, it has an unmarked lower mandible, the slight darkening he refers to is clearly not black (or even dusky) IMHO but likely a different tone as illustrated here
http://orientalbirdimages.org/search.php?Bird_Image_ID=124769&Bird_ID=1808&Bird_Family_ID=&Location= That said, I concur with his point made about a small area of black distally at the side of the bill would not always be visible, particularly from below, but that does not apply here.
Assessment of wing-bars from this angle is extremely difficult, but I would take a slight issue with John when he says this pattern, i.e two wing bars, is unusual for ECW. A feature oft quoted in literature when the reality is a significant number exhibit a second, anterior wing bar. Hellstrom refers to it as 'occasional' in his latest offering Ageing and Sexing of Migratory East Asian Passerines. A feature which is clearly visible are the contrasting paler, yellow-green outer margins to the outer greater coverts which is a feature of ECW vs AW where the coverts are uniform in this respect, similarly TBW http://orientalbirdimages.org/search.php?Bird_Image_ID=163779&Bird_ID=1802&Bird_Family_ID=&Location=
The underparts look much better in the lightened image (thanks MacNara) though the yellow patch in the centre of the lower breast is slightly disconcerting; ECW does have pale yellow streaks to the underparts but these would normally be lost in digital images. The under tail coverts do look like they might uniform yellow. https://macaulaylibrary.org/asset/1...0.1830260848.1610791608-1351674767.1609754812 for comparison. MacNara, the yellow 'wing tuft' you refer to belong to the underwing coverts/axillaries, often yellow in Phylloscopus and usually visible, they are actually brighter in ECW than AW.
One final observation, blowing up the image, there appear to be a couple(?) of pale, loose feathers above (and just beyond) the rear end of supercilium, the position equating to roughly where the coronal stripe may terminate, this for comparison. https://macaulaylibrary.org/asset/1...5.1830260848.1610791608-1351674767.1609754812
This is not an easy bird by any means but I am leaning towards Eastern Crowned.
Grahame
sandwich311
Well-known member
Thanks everybody for the detailed and incredibly informative responses. I wish I had more pictures from different angles but it was literally a one click and then gone.
I really appreciate the time and effort you have taken.
Thanks again, Rob
I really appreciate the time and effort you have taken.
Thanks again, Rob
I have loooked at this again a few times since yesterday, and increasingly I think this is Eastern Crowned. One thing is the bill colour. Although my experience is that the bill colour of KLW varies with angle and light, I agree with Grahame that in this shot a black tip to the bill should be clearly visible if it was KLW.
Also, I think it's much more likely to be Eastern Crowned in Korea in August. ECW comes through my spot in mid-April going north and mid-October coming south. (Some books show it breeding in my area, but I've never heard of this in real life - if it does, then it's much higher up than the 100m asl where we are.)
Indeed the only book that I have which splits the three Arctic complex species (a Japanese book) doesn't show Kamchatka LW as going anywhere near Korea (and as I said, KLW comes through my area - not that far from Korea - in June and October, significantly later on northern spring passage than ECW), but has ECW breeding in Korea. (Infuriatingly, this book has illustrations of all three Arctic complex birds, but they are all from different angles - side on, side from above, and side from below front - so it's impossible to work out which differences between the three are supposed to be significant.)
(To be clear: my edit to my post #5 was before Grahame posted, so this is not just a reaction to Grahame's comments.)
Also, I think it's much more likely to be Eastern Crowned in Korea in August. ECW comes through my spot in mid-April going north and mid-October coming south. (Some books show it breeding in my area, but I've never heard of this in real life - if it does, then it's much higher up than the 100m asl where we are.)
Indeed the only book that I have which splits the three Arctic complex species (a Japanese book) doesn't show Kamchatka LW as going anywhere near Korea (and as I said, KLW comes through my area - not that far from Korea - in June and October, significantly later on northern spring passage than ECW), but has ECW breeding in Korea. (Infuriatingly, this book has illustrations of all three Arctic complex birds, but they are all from different angles - side on, side from above, and side from below front - so it's impossible to work out which differences between the three are supposed to be significant.)
(To be clear: my edit to my post #5 was before Grahame posted, so this is not just a reaction to Grahame's comments.)
Grahame Walbridge
Well-known member
For up to date information on status of ECW and the 3 members of the 'Arctic' complex in Korea see http://www.birdskoreablog.org/?p=20395
With regards to timing, local breeding Eastern Crowned commence dispersal through July, numbers later augmented by birds from more northerly populations (Jul-Sep) 'Arctic' Warbler passage spans mid Aug-mid Oct, the earliest birds more likely borealis which averages (and peaks) earlier than the scarcer examinandus,
Separation of 'Arctic'warblers remains dependant on vocalisations but perfectly doable with experience and a good ear + recording helps to confirm.
Grahame
With regards to timing, local breeding Eastern Crowned commence dispersal through July, numbers later augmented by birds from more northerly populations (Jul-Sep) 'Arctic' Warbler passage spans mid Aug-mid Oct, the earliest birds more likely borealis which averages (and peaks) earlier than the scarcer examinandus,
Separation of 'Arctic'warblers remains dependant on vocalisations but perfectly doable with experience and a good ear + recording helps to confirm.
Grahame
