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Rishiri Island, Hokkaido, Japan - bird identification (1 Viewer)

R

Ross Thompson

Member
United Kingdom
Hello everyone

I've just com back from some birdwatching at the Otatomarinuma Swamps on Rishiri Island, Hokkaido (a really interesting place, btw - got my first Japanese Robin and a vagrant Taiga Flycatcher). I have a few identification questions though.

Pictures 1 and 2 - There were a lot of Masked Buntings around. However, are these photos of a Black-faced Bunting, perhaps? I note the lack of any yellow 'bid'. I know they are not common in Japan, but Rishiri is something of a migrant trap.
Pictures 3 and 4 - This is some kind of Flycatcher, and I am provisionally going for Grey-streaked Flycatcher. However, both Dark-sided and Asian Brown Flycatchers are not impossible either.
Picture 5 - Probably this is a Japanese Bush Warbler. However, it was quite a bit bigger than other JBWs I've seen and, due to the area, I was thinking a Sakhalin Grasshopper Warbler might also be a possibility.

Any help would be appreciated.

Many thanks,
Ross
 

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I'll leave the separation of the buntings and the bush warbler to those who've seen them, but your flycatcher should be asian brown - note broad bill, with yellow base to the lower mandible - clincher for ABF. Grey streaked has an all dark bill, with just a pale marking at join of the mandible gape.
 
The bush warbler-ish bird looks like JBW and -to me at least, they look very variable in size (and shape). But I don't see clear distinction points between the two species. On the other hand, should Sakhalin not have a shorter tail and a less yellowish rump area? I have no experience with Sakhalin though, not even online, as in inaturalist they are not recorded in Japan (which needs some looking into).

cheers,
Gerben
 
Its a Japanese Bush Warbler Ross. Gerben mentions size variability which is due to sexual dimorphism, males appreciably larger than females. Sakhalin Grasshopper has a totally different structure; bill is heavier, P1 is much shorter, pp is much longer, undertail coverts are long and tail is evenly graduated and much fuller. Plumage is warmer brown above and darker overall. Compare ML361333311 - Sakhalin Grasshopper Warbler - Macaulay Library

Grahame
 
The bunting is not a classic adult male Black-faced. On Black-faced, the throat and upper breast would be darker greyish, similar to the rest of the head and distinctly different from the underparts. It's a bit tricky to judge on your photo because of the backlighting but on your bird these areas appear to be yellowish, more similar to the underparts and contrasting with a black throat/grey head (more obvious on the 2nd photo). Young male Black-faced can show a pattern similar to this as they moult into breeding plumage, but I would expect most to be more advanced by now.

I'm not experienced with Masked, so it might be useful to get feedback from someone who is. But personally I don't really see anything here that wouldn't fit Masked, especially as it is the more likely of the two species.
 
Grahame Walbridge said:
Its a Japanese Bush Warbler Ross. Gerben mentions size variability which is due to sexual dimorphism, males appreciably larger than females. Sakhalin Grasshopper has a totally different structure; bill is heavier, P1 is much shorter, pp is much longer, undertail coverts are long and tail is evenly graduated and much fuller. Plumage is warmer brown above and darker overall. Compare ML361333311 - Sakhalin Grasshopper Warbler - Macaulay Library

Grahame
Click to expand...
How common is that in passerines Grahame, not sure I've read this before?
 
dwatsonbirder said:
I'll leave the separation of the buntings and the bush warbler to those who've seen them, but your flycatcher should be asian brown - note broad bill, with yellow base to the lower mandible - clincher for ABF. Grey streaked has an all dark bill, with just a pale marking at join of the mandible gape.
Click to expand...
Many thanks - They're all new species to me, so I'm grateful for the input.
 
Grahame Walbridge said:
Its a Japanese Bush Warbler Ross. Gerben mentions size variability which is due to sexual dimorphism, males appreciably larger than females. Sakhalin Grasshopper has a totally different structure; bill is heavier, P1 is much shorter, pp is much longer, undertail coverts are long and tail is evenly graduated and much fuller. Plumage is warmer brown above and darker overall. Compare ML361333311 - Sakhalin Grasshopper Warbler - Macaulay Library

Grahame
Click to expand...
Many thanks. Being up in Hokkaido I was hoping for some of the Grasshopper Warblers from that area. How would my bird compare with a Middendorf's Warbler? Again, from superficial inspection of the photos, I struggle to see much of a difference.
 
johnallcock said:
The bunting is not a classic adult male Black-faced. On Black-faced, the throat and upper breast would be darker greyish, similar to the rest of the head and distinctly different from the underparts. It's a bit tricky to judge on your photo because of the backlighting but on your bird these areas appear to be yellowish, more similar to the underparts and contrasting with a black throat/grey head (more obvious on the 2nd photo). Young male Black-faced can show a pattern similar to this as they moult into breeding plumage, but I would expect most to be more advanced by now.

I'm not experienced with Masked, so it might be useful to get feedback from someone who is. But personally I don't really see anything here that wouldn't fit Masked, especially as it is the more likely of the two species.
Click to expand...
Thanks for the input. A Masked Bunting was my first thought, but what made me wonder was the lack of yellow connecting the throat to the bill. In every male Masked Bunting that I've seen (which is a lot - they are common here, in Japan), the yellow covers the whole throat area whereas, in my bird, the throat is more-or-less grey with some yellow streaks. I fully agree that it can't be a typical adult BFB, but it really doesn't feel like a typical adult MB either. I can understand why they were once considered the same species. :)
 
Andy Adcock said:
How common is that in passerines Grahame, not sure I've read this before?
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Many passerines show some sexual dimorphism in size (males are usually larger), but this is more pronounced in Horornis than most - I'm not sure that any other passerine genus/species shows anywhere near so much size difference. I don't know why this should be the case.

In Hong Kong, we use different ring sizes on male and female Manchurian Bush Warbler because of the large size difference. On average, males are approximately 22% longer-winged and approximately 60% heavier than females, with no overlap in most measurements. For comparison, females are similar in size to smaller Acrocephalus (eg Black-browed Reed Warbler) and males are similar to Oriental Reed Warbler.

I've attached a graph of wing length against weight of Manchurian BW in Hong Kong to show the difference between the sexes (I think the low outlier on weight for one male here is due to a recording error).
 

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Ross Thompson said:
Many thanks. Being up in Hokkaido I was hoping for some of the Grasshopper Warblers from that area. How would my bird compare with a Middendorf's Warbler? Again, from superficial inspection of the photos, I struggle to see much of a difference.
Click to expand...
Your bird is not any of the Grasshopper Warblers - for example, it has shorter undertail coverts, less rounded tail shape and stronger hind toe than any Locustella/Helopsaltes. I agree with others that it looks like a Japanese Bush Warbler.
 
Ross Thompson said:
Thanks for the input. A Masked Bunting was my first thought, but what made me wonder was the lack of yellow connecting the throat to the bill. In every male Masked Bunting that I've seen (which is a lot - they are common here, in Japan), the yellow covers the whole throat area whereas, in my bird, the throat is more-or-less grey with some yellow streaks. I fully agree that it can't be a typical adult BFB, but it really doesn't feel like a typical adult MB either. I can understand why they were once considered the same species. :)
Click to expand...

As I mentioned, I haven't seen Masked, so have no experience. But my understanding was that they can often show a dark chin between the yellow throat and the bill, rather than the yellow reaching all the way to the bill. From online photos, the extent of black seems to be variable. This is the pattern that I think I see on your bird, which seems to have a black chin but yellow throat and breast.

Adult male Black-faced also have the black chin, but below this they are grey on the throat and the breast, becoming yellow/white only on the belly. But as mentioned before, they can have a tricky transitional stage as they moult into breeding plumage, when they have a black chin of breeding plumage but yellow breast of winter. Where Masked is common, I think proving ID of a transitional Black-faced may be very difficult (just as here, where Black-faced is common, proving a Masked would be very difficult!)

Compare this Masked: ML617453088 - Masked Bunting - Macaulay Library
And this Black-faced: ML618361756 - Black-faced Bunting - Macaulay Library
 
johnallcock said:
As I mentioned, I haven't seen Masked, so have no experience. But my understanding was that they can often show a dark chin between the yellow throat and the bill, rather than the yellow reaching all the way to the bill. From online photos, the extent of black seems to be variable. This is the pattern that I think I see on your bird, which seems to have a black chin but yellow throat and breast.

Adult male Black-faced also have the black chin, but below this they are grey on the throat and the breast, becoming yellow/white only on the belly. But as mentioned before, they can have a tricky transitional stage as they moult into breeding plumage, when they have a black chin of breeding plumage but yellow breast of winter. Where Masked is common, I think proving ID of a transitional Black-faced may be very difficult (just as here, where Black-faced is common, proving a Masked would be very difficult!)

Compare this Masked: ML617453088 - Masked Bunting - Macaulay Library
And this Black-faced: ML618361756 - Black-faced Bunting - Macaulay Library
Click to expand...
Thanks for the detailed info. Yes - it can be annoying when its not really possible to prove an ID one way or the other.
 

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