Which Skua species in Japan (1 Viewer)

I saw this skua species at the weekend on a pelagic trip in Hokkaido.

I have no real experience of IDing skuas. I thought it looked pretty chunky (I initially thought it was an immature Slaty Backed Gull when I saw it in the distance) and when I reviewed the photos I noticed the small white wing patches and (to my eyes) relatively thick all dark bill. I also noted the whitish mottled belly. Other more experienced pelagic birders on the boat identified it as a South Polar Skua. Other observers on the boat saw what was believed to be another SPS later on, there is no way of knowing if it was the same individual.

After posting the pics on my blog I got a comment suggesting it was in fact a Pomarine Skua.

On consulting Mark Brazil's fieldguide it doesn't become much clearer.........it kind of looks like both.........

The photos are crap, 100% crops with the shadows lightened a lot to show any diagnostic features.

Any ideas? Any opinions would be gratefully received.

I don't see how it can be a SPS with a bill like that. It doesn't seem like the right shape either, but I say that from limited experience. Doesn't seem chunky enough IMO.

Thanks for the comment.

You mean you think the bill is too thin? Or the colour?

The white belly on #2 is what is causing me most doubt. None of the pics in my books show that on a SPS.

Hi Stu. I'm only looking at it on my phone but it looks suspiciously like a Pom. The head pattern, pale marked belly, barring around the base of the tail and general structure seem to fit Pom more than SPS.

Chris

Clearly a Pomarine in my opinion mainly from features given already by Chris. A SPS simply can't look like this. ;-)

Thanks a lot for the comments. A Pomarine it is then.........

Another one

I came across this thread just as I was sorting some photos from a weekend in Hokkaido (off Rauso, coast of Shiretoko, between Hokkaido and Kunashiri), so rather than add a new thread I'll post here hoping you can give an identification.

Unlike HokkaidoStu, I have never seen any northern seabirds, and I puzzled a lot last night over this bird (the easiest of the ones that aren't obvious because at least the photos are clear). I think it's an Arctic Skua, but I don't know if it's an adult in winter plumage or a juvenile.

From some angles, the bill looked shearwater-like, but in the best photos it didn't. The tail seems not to have central plumes, but from the four books I looked at, I can't work out whether the eclipse bird should have something or not.

Opinions gratefully received.

I'd say that's also a Pomarine.

Thank you OlaB.

One reason (apart from inexperience) that I didn't consider Pomarine Skua is that in all the books I have (both photographic and painting) the Pomarine Skua has a white collar, or a long tail, or most usually both, in all plumages.

Also, I saw it fighting out with a Black-legged Kittiwake, and one of the books shows precisely the scenario of a Kittiwake being harrassed by an Arctic Skua, so I was psychologically influenced.