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Warbler ID, South Korea (Eocheong Island), 9/10/21 (1 Viewer)

sandwich311

Well-known member
I wasn't able to get any sound recordings unfortunately. Would this be most likely Arctic Warbler or is it simply Yellow-browed?
Thanks, Rob
 

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HouseCrow

Well-known member
just a quick note, if it is Arctic Warbler-like, then I suppose in Korea too it would be Arctic Warbler complex as Arctic Warbler, Kamchatka Leaf Warbler and Japanese Leaf Warbler are considered not distinguishable in the field. Or is that information already outdated?

a 2014 article about the issue: Ask The Experts: The Arctic Warbler Splits

sidenote: With Eastern Crowned Warbler also recorded in Western Europe, I wonder why migrating Arctic Warbler would still be ID'd to species level there though (on sight alone, of course)

cheers,
Gerben
 
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Jean FRANCOIS

Well-known member
Borealoides and examinandus are still quite different in appearance and Korea is rather off their roads, especially for borealoides. Borealis is by far the most likely.
 

HouseCrow

Well-known member
If I am not mistaken Japanese Leaf Warbler (Phylloscopus xanthodryas) is a split from Arctic Warbler, just like Kamchatka Leaf Warbler (P. examinandus). I understand that in direct comparison they may look a bit different but that is hardly ever the situation in the field of course, hence Per Alstrom's remark that they can only be safely distinguished by call or song (referenced in the article I mentioned above)

I am not saying it is this or that, just that I wonder how far we are now with this issue.


cheers
Gerben
 
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HouseCrow

Well-known member
you're most welcome

@sandwich311 do you upload your records to any of the recording sites?
I generally find that all three I know are very useful (each in their own way): ebird,org inaturalist.org and observado.org (the latter two for all nature records)

I am always interested in seeing records of the East Asian coastal region.

cheers,
Gerben
 

andyb39

Well-known member
borealoides is Sakhalin Leaf Warbler...another species forming a pair with yet another species: Pale-legged Leaf Warbler (P. tenellipes)

tough matter these leafers )

cheers
Gerben
I see - for some reason I thought Jean Francois was referring to xanthodryas by a different name. I'm not sure where the idea of Sakhalin came from, to be honest. The OP bird is clearly one of the Arctic complex - both borealis and examinandus are possible.
 

HouseCrow

Well-known member
I don't know if Jean Francois really intended to talk about borealoides. Why though would Japanese Leaf Warbler not be an option too. It may be a rare vagrant in Korea but it is next door and Japanese Leaf Warbler not rare in Japan itself. It is a migrant too; again if Eastern Crowned Warbler is considered a vagrant in Western Europe, why not Japanese Leaf in Korea.

I am not saying it is one, I only suggest that I think a choice cannot be made between these three species (IF it is actually Arctic-warblerish) I would be dishonest if I said that I can decide that. I am too much of a eagerly learning novice in East Asian Phylloscopus matters to take an active stance.


cheers,
Gerben
 

Grahame Walbridge

Well-known member
I don't know if Jean Francois really intended to talk about borealoides. Why though would Japanese Leaf Warbler not be an option too. It may be a rare vagrant in Korea but it is next door and Japanese Leaf Warbler not rare in Japan itself. It is a migrant too; again if Eastern Crowned Warbler is considered a vagrant in Western Europe, why not Japanese Leaf in Korea.

I am not saying it is one, I only suggest that I think a choice cannot be made between these three species (IF it is actually Arctic-warblerish) I would be dishonest if I said that I can decide that. I am too much of a eagerly learning novice in East Asian Phylloscopus matters to take an active stance.


cheers,
Gerben
Gerben, in terms of status, xanthodryas is a very scarce/rare visitor to Korea (< 10 annually) whereas, borealis is by far the most numerous and examinandus is a regular, but much scarcer, passage migrant (< 100 annually) per BirdsKorea. Since the question was asked earlier, there have been no advancements in field identification of the complex, vocalisations are still key to substantiated claims to species level. JLW is the largest, averaging heavier-billed (deeper and broader-based) and plumage-wise, it's the brightest, with strongest yellow saturation, AW is the smallest and dullest with KLW somewhere in between but, crucially, differences are average so, there is overlap between the 3 species. In the hand, crucial measurements include bill, length of P1 and wing.

Looking closer at the OP, which appears to be a 1st-w on account of it's fresh remiges and coverts, plumage-wise, there seems no reason to suspect xanthodryas IMHO, the yellow tones are very reduced/almost absent, upprparts are quite dull and bill doesn't look particularly heavy so, suspect it's likely a AW/KLW. However, for recording purposes safest to put down as an 'Arctic' warbler sp- AW/KLW/JLW.

Grahame

.
 
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andyb39

Well-known member
I see Grahame has since replied, but I was going mostly on the lack of records of JLW for S Korea on eBird - only 8 observations, chiefly in spring. There's a link to 2 images but they've been removed, suggesting misidentification or lack of certainty. Whatever your source, it seems that JLW is by far the least likely to occur in S Korea. I would say that the OP bird doesn't look that much like this species either. Apart from the colour tones and bill shape Grahame has mentioned, there's a distinct black mark on the lower mandible, which is often reduced or absent in JLW, and the supercilium is long and distinct after the eye - in JLW, it's often thin and weak, sometimes broken, beyond the eye. Another supposed pointer is that the lower half of the eye-ring is sometimes thicker and more prominent than on the other two. These features can be observed in the main image on eBird but it doesn't take much browsing to find other images in which they're not apparent!

I would agree with Grahame that this bird is best left as AW/KLW. They look practically identical in images, although it seems that spring KLW individuals have a more khaki tone and sometimes sport a yellowish vent - this was the case with a bird I saw in Japan two years ago and the vent can be seen in this individual: Kamchatka Leaf Warbler.
 

HouseCrow

Well-known member
thanks Grahame and Andy for the status info and further information on the small differences between the three species.
I put maybe too much emphasis on the strict use of the Arctic Warbler Complex label in areas where none of the three species is highly unlikely (East Asia, Alaska, Western Canada (?) to occur. I accept that the regular arctic warbler in Northern Scandinavia is recorded as Arctic Warbler....even though a singing Kamchatka Warbler turned up in Finland in july a few years ago.

back to my own Japanese brown little leafers

cheers,
Gerben
 

sandwich311

Well-known member
you're most welcome

@sandwich311 do you upload your records to any of the recording sites?
I generally find that all three I know are very useful (each in their own way): ebird,org inaturalist.org and observado.org (the latter two for all nature records)

I am always interested in seeing records of the East Asian coastal region.

cheers,
Gerben
Yes, I upload my records to ebird. I usually try to get a photo and a sound recording to confirm an ID, especially for when it come to leaf warblers! I did manage to get a recording on the BirdNET app earlier in the day which picked up an Arctic Warbler in a different area on the island. I'll put this one down as AW/KLW/JLW as Grahame and Andyb39 mentioned.
 
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