arctic warbler-ish? | Hegurajima, jp | may 2018 (1 Viewer)

HouseCrow · Jan 30, 2019

Here's a second Leaf Warbler of my 4 day trip to Hegurajima, Japan.
It was seen together with an Eastern Crowned Warbler and there's plenty of choice really: Sakhalin, Kamchatka, Japanese, Arctic, (Pale-legged). Fact is, it may be that a sound recording is needed for a positive ID. There are 10's of soundfiles in my archive but they don't match in time with the photo-files yet...

Do you have a suggestion?
Hope to hear from you

cheers,
Gerben

arcadillor · Jan 31, 2019

its a member of Arctic group，I think Arctic warbler

Grahame Walbridge · Jan 31, 2019

arcadillor said:
its a member of Arctic group，I think Arctic warbler

Agree its one or other of the Arctic complex but beyond that it's not identifiable to species in the absence of a sound file. Higher quality images might provide some clues.

Grahame

MacNara · Jan 31, 2019

arcadillor said:
I think Arctic warbler

I'd be interested to hear why.

Arctic, after the split, is the least likely of the three to be seen in Japan, even in Hegura. Kamchatka seems to be by a long way the most common in Hegura. None of the very expert Japanese birders (not me, I'm just an intermediate) I know would give an ID on an 'Arctic complex' photo without a sound file that was definitely from the same bird.

What features make you think it's Arctic?

arcadillor · Jan 31, 2019

MacNara said:
I'd be interested to hear why.

Arctic, after the split, is the least likely of the three to be seen in Japan, even in Hegura. Kamchatka seems to be by a long way the most common in Hegura. None of the very expert Japanese birders (not me, I'm just an intermediate) I know would give an ID on an 'Arctic complex' photo without a sound file that was definitely from the same bird.

What features make you think it's Arctic?

in my impression Kamchatka has a thinner and yellower supercilaris，and Japanese's underparts much yellower
but these characters are not accurate completely

HouseCrow · Jan 31, 2019

Having read through quite a few pages on the subject i think it's safe to say that on sight alone this bird is hardly ID-able. If you're good in reading wingformulae (not me!) you might be able to tell apart Japanese Leaf from the other 2, since they have -apparently- a very long longest flightfeather (P9 it is I think)

Grahame, are there features I missed that might be in higher quality photos? I could upload some others to flickr for a better view...but none are really HQ photos.

MacNara, you are probably right that Kamchatka is the commoner species there. But since my first Leaf Warbler there was an apparent Eastern Willow Warbler...anything goes (well...almost)

Arcadillor, the yellower supercilium vs yellower underparts may be features but I doubt they are to be judged in fieldshots like these. In the hand of course, then it'll be a different matter.

I will try to find more info on it...and try to fix my video-photo-timematching problems (thanks Sony)
I don't think i have a definite soundfile of this bird but who knows.

cheers
Gerben

MacNara · Jan 31, 2019

HouseCrow said:
MacNara, you are probably right that Kamchatka is the commoner species there. But since my first Leaf Warbler there was an apparent Eastern Willow Warbler...anything goes (well...almost)

Eastern Crowned? I meant that Kamchatka was the commonest of the three birds split from the (old) Arctic Warbler. (Although, in fact, I imagine Kamchatka is the commonest of all the leaf warblers.) Eastern Crowned seems to be the next most common. (But this may be a prejudice because this is true where I live.) Arctic (borealis after the split) is very rare in Japan, and would attract birders from a long way (which is why I asked arcadillor why he went for Arctic). I also have the impression that Japanese Leaf heads straight for the mountains of Honshu, and is only found on places like Hegura when it's lost it's way.

HouseCrow said:
Arcadillor, the yellower supercilium vs yellower underparts may be features but I doubt they are to be judged in fieldshots like these. In the hand of course, then it'll be a different matter.

I wonder about this. Although some books try to differentiate between the three on looks, experienced Japanese birders I know say voice is the only way to be sure. Possibly if you had all three in hand at the same time there might be visual differences strong enough to differentiate, but on a single bird, even in hand, unless it makes a sound I'm not convinced. After all, there are seasonal (and individual) differences in plumage to consider. I have seen it said that Hokkaido 'Kamchatka' and Russian 'Kamchatka' vary in their greyness or yellowness.

Grahame Walbridge · Jan 31, 2019

MacNara said:
Eastern Crowned? I meant that Kamchatka was the commonest of the three birds split from the (old) Arctic Warbler. (Although, in fact, I imagine Kamchatka is the commonest of all the leaf warblers.) Eastern Crowned seems to be the next most common. (But this may be a prejudice because this is true where I live.) Arctic (borealis after the split) is very rare in Japan, and would attract birders from a long way (which is why I asked arcadillor why he went for Arctic). I also have the impression that Japanese Leaf heads straight for the mountains of Honshu, and is only found on places like Hegura when it's lost it's way.[/QUOTE}

The earlier phylloscopus to which Gerben is referring to can be seen in this thread https://www.birdforum.net/showthread.php?t=371745 which is a yakutensis Willow Warbler.

Grahame

MacNara · Jan 31, 2019

Grahame Walbridge said:
The earlier phylloscopus to which Gerben is referring to can be seen in this thread https://www.birdforum.net/showthread.php?t=371745 which is a yakutensis Willow Warbler.

Thanks Grahame. Mark Brazil says Willow Warbler is a 'rare, probably annual' migrant in Japan, other books say 'annual in Hegurajima, occasional elsewhere'. So Gerben was lucky. On my first visit to Hegura (a one night stay in the autumn not long after I started birding), we got Booted Warbler and Grey-necked Bunting, each of which had only a handful, if that, of records in Japan. Hegura is a strange place.

But I don't think this actually affects my main point which is that the three 'Arctic complex' birds can't be split visually, certainly with only one bird. I wasn't saying any of the three couldn't be there; just that Kamchatka was much more likely than the other two (and new Arctic by a long way the least likely of all), and that only sound would enable you to give a certain ID.

Grahame Walbridge · Jan 31, 2019

I am not disagreeing with the main thread of your argument but I should make the point, that in fresh plumage at least, Japanese Leaf should be diagnosable in the hand to an experienced observer. I was recently in conversation with Phil Round on the very subject had here is what he had to say:

'JLW is larger than KLW as you say, with a markedly thicker bill. There is overlap in wing length, at least, between the largest (male) Kamchatka and the smallest (female) Japanese, just as there is, say, between large male Arctic and female Kamchatka. The bill of Japanese is markedly stouter Calls are diagnostic.
I have now had four Japanese LW in the hand and besides being obviously brighter, more or less evenly yellow on the underparts, they are obvious on size right away. Even a (relatively short-winged -70.5 mm-by Japanese LW standards) female was obviously a large warbler right away. But it can be surprisingly difficult to see the extent of yellow in the field, with reflected green light off foliage (from observations on a newly released bird that was subsequently watched, perched, while preening after release).'

It's worth restating his word of caution re field ID; the amount of yellow saturation, which includes the ventral region, is a key feature but it can be tricky to see in the field, equally these yellow tones are often 'lost' in digital images which presents its own problem with regards image-based identification.

In short, like you, I would not advocate making a firm ID from images in the absence of a sound recording.

Some useful reading https://www.researchgate.net/publication/280383942_A_record_of_Japanese_Leaf_Warbler_Phylloscopus_xanthodryas_in_Thailand and an autumn individual here for comparison; the heavy bill is obvious but the yellow tones are rather more subdued though there is no way of knowing whether or not this is a true likeness http://orientalbirdimages.org/search.php?Bird_ID=1808&Location=

Grahame

MacNara · Jan 31, 2019

Grahame Walbridge said:
I was recently in conversation with Phil Round on the very subject and here is what he had to say:

'JLW is larger than KLW as you say, with a markedly thicker bill. There is overlap in wing length, at least, between the largest (male) Kamchatka and the smallest (female) Japanese, just as there is, say, between large male Arctic and female Kamchatka. The bill of Japanese is markedly stouter. Calls are diagnostic.
I have now had four Japanese LW in the hand and besides being obviously brighter, more or less evenly yellow on the underparts, they are obvious on size right away. Even a (relatively short-winged -70.5 mm-by Japanese LW standards) female was obviously a large warbler right away. But it can be surprisingly difficult to see the extent of yellow in the field, with reflected green light off foliage (from observations on a newly released bird that was subsequently watched, perched, while preening after release).'

In short, like you, I would not advocate making a firm ID from images in the absence of a sound recording.

Grahame

Well, Mark Brazil (Birds of East Asia) says that Kamchatka LW in Kamchatka is slightly larger and with a heavier bill than Japanese, thus contradicting Phil Round (I'm sorry, but I have no idea who Phil Round is). Brazil also says that Sakhalin / Hokkaido Kamchatka are smaller than Kamchatka Kamchatka, but without reference to JLW.

Grahame Walbridge · Jan 31, 2019

MacNara said:
Well, Mark Brazil (Birds of East Asia) says that Kamchatka LW in Kamchatka is slightly larger and with a heavier bill than Japanese, thus contradicting Phil Round (I'm sorry, but I have no idea who Phil Round is). Brazil also says that Sakhalin / Hokkaido Kamchatka are smaller than Kamchatka Kamchatka, but without reference to JLW.

With respect MacNara you are quoting an out-of-date reference and I pointed this obvious error out to you in an earlier PM; JLW is (on average) the larger and with a broader-based bill and further, the plates of JLW and KLW in the new Brazil field guide are the wrong way round! The latter may be a simple error, but the text is quite simply incorrect.

Grahame

MacNara · Jan 31, 2019

Grahame Walbridge said:
With respect MacNara you are quoting an out-of-date reference and I pointed this obvious error out to you in an earlier PM; JLW is (on average) the larger and with a broader-based bill and further, the plates of JLW and KLW in the new Brazil field guide are the wrong way round! The latter may be a simple error, but the text is quite simply incorrect.

Well, Grahame, I'll take your word for that. The latest Japanese book I have does indeed say that JLW is slightly larger (lenghtwise, it doesn't say anything about the bill).

If you look at HBW, there is almost no detail about Kamchatka and Japanese LW. And I have the impression that they haven't changed their text for Arctic much since the split.

There are brief entries for Kamchatka and Japanese, but the much longer entry for Arctic still talks about this bird breeding in Japan, despite the fact that part of the point of the split is that (new) Arctic doesn't breed in or near Japan - or at least that's how I have understood the split.

My latest Japanese book from 2016 (and since you say that Brazil's new Japan book is has the plates the wrong way around, you presumably won't argue that the 2016 book is out of date compared to Brazil) tries to differentiate the three new species, but specifically states that (new) Arctic is a passage migrant and not a breeding bird. Thus, HBW would be seriously incorrect about this.

I have the impression that a lot of things are still up in the air about this split, except the vocalisation.

Grahame Walbridge · Jan 31, 2019

arcadillor said:
in my impression Kamchatka has a thinner and yellower supercilaris，and Japanese's underparts much yellower
but these characters are not accurate completely

If only it were so simple, even Arctic can be very bright in fresh plumage https://www.shanghaibirding.com/2017/07/01/kamchatka2/ and here is one of three JLW's trapped on Koh Man Nai in Apr 2018 for comparison-note extensive yellow tones and heavy bill. https://www.facebook.com/wettrustasia/photos/pcb.1759305074113031/1759302644113274/?type=3&theater and https://www.facebook.com/wettrustasia/photos/pcb.1759305074113031/1759302610779944/?type=3&theater

Grahame

HouseCrow · Feb 1, 2019

Thanks again for your replies. I was expecting this to end it this way. But since some people were so determined about my Willow Warbler I was somehow hoping this too turned out to be a doable ID: "3 species in the arctic warbler complex but this one is Japanese Leaf because of the long 9th primary"

Probably in a forest near Saitama it would be a different matter, but on Hegura anything goes. The one downside to an otherwise great Treasure Island for birdwatchers.
I will sadly put the record down as leaf warbler spec (kamchatka, Japanese Leaf or - unlikely - Arctic Warbler)

It looks as though there will be no agreement in the forseeable future on defining features for all three arctics in the field.

sidenote: I came across a research paper (2011) somewhere online which mentioned about 7 yearly records of Willow Warbler in Japan.

sidenote: I recently subscribed to HBW hoping to have a Cramp-experience (Birds of the Western Palearctic) but it's a bit less impressive to be honest.

On to the next ID

regards,
Gerben

interesting reads on the subject (including those mentioned above by Grahame)
https://www.researchgate.net/profile/Per_Alstroem/publication/322665905_Identification_of_vagrant_Asian_leaf_warblers_in_Europe/links/5a67aa16a6fdcce9c106e8cd/Identification-of-vagrant-Asian-leaf-warblers-in-Europe.pdf
https://www.shanghaibirding.com/2017/06/06/kamchatka/
http://www.bird-research.jp/1_shiryo/seitai/meboso.pdf
https://www.researchgate.net/publication/280383942_A_record_of_Japanese_Leaf_Warbler_Phylloscopus_xanthodryas_in_Thailand

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