all dark storm-petrel with forked tail | 15km East of Toshima, Japan | 8 march 2020 (1 Viewer)

[HouseCrow]

I have been going through my still unseen archive of shots fired on my last japan trip (foreshortened by covid risk increase).
What would you make of this bird which in the field I put down as storm-petrel spec.
There are a few all dark, fork-tailed storm-petrels in the area. I think Tristram's has the best papers for my bird (no white to primaries) but I am not confident at all. Maybe young Matsudaira is a better fit.

I have been leafing through sites, books and this gorgeous site: Stormies – Seabirding of Japan but I fail to find a definite answer...which may not be had based on these distant shots alone/

link to inaturalist records of that day, including this one: Observations

This is only the second storm-petrel ever I see so.... not much of an expert on seabirds.




Hope to read from you
cheers,
G e r b e n

PS. very eager to go back some day for another trip with calmer seas and more sun...although this was one of my best birding experiences.

 

[DMW]

Tristram's would seem a good call at that time of year. I think Matsudaira's would look longer-winged, but hopefully somebody who knows what they are talking about will respond.

 

[RafaelMatias]

This is hard stuff, based on these 3 pics alone. The first step is to decide which side (upper vs. under) of the bird are they showing: after some time looking at them I believe they all show the underside only, but this is not 100% clear. In this case, the presence of pale shafted primaries cannot be ascertained from these pics.
In any case there are "only" 3 contenders: Matsudaira's, Swinhoe's and Tristram's. In my opinion the tail fork is way too deep for Swinhoe's, and seems to best suggest Tristram's, but this is far from a definite answer, sorry.


edit: crossposted with DMW

 

[HouseCrow]

Thanks for the replies. It is good to know that I am probably not miles off this time.
I checked the other photos, none show more than the underwing, each time the upperwing would be visible, the bird is hidden behind a wave.

Funny thing though is that in a photo moments later, well behind my bird, another storm-petrel can be seen with some fork-tail and light marks on the upperwing. It doesn't mean anything but it is funny that that feature is visible even on this tiny crop.
I will not try to ID that one, but it seems at least not to be a Tristram's.*..unlike hopefully the subject bird.

*edit: Wrong assumption

Anyway, not sure if certainty can be had on the subject bird. That fork is substantial and not a photo-effect or something.

cheers,
G e r b e n

 

[DMW]

What makes you think the second bird wouldn't be Tristram's? I agree it's likely unidentifiable but it I don't think anything excludes Tristram's.

 

[HouseCrow]

Thanks Dmv, sorry for that hasty conclusion... I did not realize these lighter coverts also fit Tristram..and most other regulars in these waters
Bl**dy difficult matter indeed.

G