Long-tailed or Arctic Skua (1 Viewer)

[robinchittenden]

I posted these photographs intially on Twitter @BirdlineEAnglia. Birders were divided as to its identity.

They were taken off the coast of Morocco in November 2014.

Anyone want to stick their neck out and ID the bird?

So far comments include:

Pro Arctic

The bird is a dark type of Arctic juvenile. On the upperwing, all primaries have white shafts and the bases of a number of outer primaries have white flashes; this excludes both Long-tailed and Pomarine.

Other features good for Arctic: the rufous brown colour of the feather fringes on the mantle (cold greyish in Long-tailed juv), the bill shape and the position of the nostril (more towards the base in Long-tailed), the brownish uppertailcoverts/lower back (white with black bands in Long-tailed juv), etc.

and
I had to read up again,the bird has more than the 2 white shafts,,and the bill Iooks Arctic to me (gonydeal to nib ratio)

and
extent of dark on lower mandible better for Arcric?

Pro Long-tailed
based on overall structure, including relative bill size and, especially at such a close range, the absence of pale tips to the primaries.

and
Long-tailed. A little bit more white on the underside of the primaries than usual but everything else is spot on

Thanks

Robin

 

[Nutcracker]

I'd tend towards the Arctic camp on bill structure and wing width, looks a mite broad-winged for LTS.

 

[Andy Adcock]

I thought that something about the barring on the rump was diagnostic of Long-tailed from past debates?

Andy

 

[Ighalo is amazing]

Long-tailed for me

 

[Andy Adcock]

Long-tailed for me

Me too FWIW

Andy

 

[smiths]

It is interesting that the debate was limited to either Long-tailed or Arctic Skua since the photographs show neither!
One strong indication for the correct species - and one that should be much more clearly stated in field guides - is that only the inner greater and median upperwing coverts have distinct pale tips, while the outer feathers have virtually no pattern. The "reptile-like" scaling on head is another good feature, as well as the strong bill, which is clearly thickest at the base.

Therefore, despite the lack of double white 'flash' on underwing, the bird is a Pomarine Skua.

 

[robinchittenden]

Thanks for that always a good idea to think outside any constraints. Would the underwing usually show the pale based under-primaries ie the double patch on underwing? And the tail looks either pointed or blunt tips but not square ended. The pale tips you mention could get worn off by November, perhaps?

Thank you everyone for their comments. Still don't know what species it is yet.

It is interesting that the debate was limited to either Long-tailed or Arctic Skua since the photographs show neither!
One strong indication for the correct species - and one that should be much more clearly stated in field guides - is that only the inner greater and median upperwing coverts have distinct pale tips, while the outer feathers have virtually no pattern. The "reptile-like" scaling on head is another good feature, as well as the strong bill, which is clearly thickest at the base.

Therefore, despite the lack of double white 'flash' on underwing, the bird is a Pomarine Skua.

 

[Andy Adcock]

Robin,
send it to the Flamborough lot via Bret, I'm surprised he hasn't chipped in already?

Andy

 

[DaveN]

Robin,
send it to the Flamborough lot via Bret, I'm surprised he hasn't chipped in already?

Andy

He's been too busy counting Sooties!

 

[smiths]

Thanks for that always a good idea to think outside any constraints. Would the underwing usually show the pale based under-primaries ie the double patch on underwing? And the tail looks either pointed or blunt tips but not square ended. The pale tips you mention could get worn off by November, perhaps?

Thank you everyone for their comments. Still don't know what species it is yet.

The plumage of this bird is still amazingly fresh. The pale tips are not worn off; they are still there. You can see thin, dull pale fringes on the greater coverts all the way outwards. It is just that the inmost are much whiter and more prominent than the rest - very typical of juv. Pomarine.

This juv Pomarine that spent a few weeks in Belgium last winter had extensive dark pattern on primary coverts below and also showed slightly pointed central tail feathers at some angles:
http://waarnemingen.be/foto/view/10069307

See also this one from a Scilly pelagic:
http://www.gobirding.eu/Images/Skuas/Pomarine/Pomarine Skua, Scilly pelagic, 12-Aug-12 (A)(47) L.JPG

I am adamant that your bird is a Pomarine Skua.

 

[robinchittenden]

It looks like you might be right. It seems others who know much more than me are swinging in your direction. Another photographer at the time has dug out some more photos (sorry haven't seen them yet) which 'clearly show the undamaged central tail feather, which is short, blunt and exactly how it should be for Pomarine.'

Well done

Robin

The plumage of this bird is still amazingly fresh. The pale tips are not worn off; they are still there. You can see thin, dull pale fringes on the greater coverts all the way outwards. It is just that the inmost are much whiter and more prominent than the rest - very typical of juv. Pomarine.

This juv Pomarine that spent a few weeks in Belgium last winter had extensive dark pattern on primary coverts below and also showed slightly pointed central tail feathers at some angles:
http://waarnemingen.be/foto/view/10069307

See also this one from a Scilly pelagic:
http://www.gobirding.eu/Images/Skuas/Pomarine/Pomarine Skua, Scilly pelagic, 12-Aug-12 (A)(47) L.JPG

I am adamant that your bird is a Pomarine Skua.

 

[Mike Langman]

HI Robin,
Its either L-t or Pom for a start.
The top side shot does look initially more L-t like but the tail length from back of tertials to end of tail mearured against the width of the arm on the bird are closer to Pom as L-t tail end in juv is subtantially. the under side shot looks much more Pom like despite the bird lacking the usually very obvious pale primary coverts forming the double whitish flash on the carpal. the body on this bird at the rear end looks much more Pom like quite heavy toward the vent - L-t are very slim here. the bill looks big and black on tip restricted to less than a 1/3 typical of Pom on most juv L-t the bill is 50/50 greyish/blue and black. Juv Poms like L-t show reduced pure white primary shafts in upper wing, Arctic are normally show more strikingly white primary shafts. A L-t in this plumage form would also show a paler upper belly/lower chest hot spot. are there cinnamon tones to the plumage if so again good for Pom.
Overall its a Pomarine Skua for me.