Is this a Caspian Gull? - Sudan (possible first record) (1 Viewer)

I photographed this gull today, which I believe may be a Caspian Gull. It was at Jebel Aulia Reservoir on the White Nile just south of Khartoum. I am not good at large gulls but the pale coloration and white primary tips seem to point to Caspian, based on the limited literature at my disposal. It was with three Lesser Black-backed Gulls. A couple of other pale 'Herring-type' gulls were also seen passing further out that may have been the same. They were part of a fairly steady stream of gulls and terns moving north.
Although Caspian Gull seems quite likely here, I have not actually come across any records, which would make this the first for the country. I therefore need to have a clear confirmation for it to be acceptable. The main authority for the country is Nikolaus' Distribution Atlas of Sudan's Birds from 1987; it only mentions heuglini, but this was before the major split of the Herring Gull complex and other forms may not have been looked for. Last year I photographed a similar bird at the same location but a bit further out. A discussion on birdforum suggested it might be Caspian, but the photos were not clear enough to confirm this (
http://www.birdforum.net/showthread.php?t=185816).
I would appreciate any comments.
Thanks

Tom

Not cachinans for me with that startlingly pale eye and thick short bill!

cheers, alan

lewis20126 said:

Not cachinans for me with that startlingly pale eye and thick short bill!

cheers, alan

Click to expand...

Thanks Alan
I also wondered about the eye colour, but Birds of the Middle East (one of the few field guides I own that shows most of the new Herring Gull splits) referred to Caspian as often having a dark eye. Do you have any suggestions for what it might be?

Tom

Hi, looks like Armenian Gull to me. Don´t know if they can be found in Sudan - perhaps North of?

Cheers

it looks like a michahellis, maybe of eastern type, to me. the only other contender with bright yellow legs, a pale iris and solid black in wingtip would be barabensis. do you have a shot where its wings are flapped upway to see underwing better?

Hi Lou, I read in most eastern-type michahellis the tip of P10 merges into mirror, creating completely white tip. What about prominent white beak-tip, dark subterminal band and much black in 3 outer P? Mantle-colour seems to be quite pale indeed.

bye

Thanks for the comments so far. I just looked up Larus michahellis and came across this photo taken in Spain (http://www.fotonatura.org/galerias/fotos/242554/lightbox/). It seems to fit quite well, having a pale eye, the same wing pattern, plus the same bill pattern, complete with pale tip and dark subterminal band. However, many other pictures of this species don't show such a bill pattern. Is bill pattern linked to age or local population, or does it vary between individuals? I don't have any decent photos of the underwing, though this one gives a better view of the underside of the wing-tip.
I still hope to be able to confirm this bird as it would be nice to be able to report it properly as a new species for Sudan (whatever it is, if its not hueglini its a first for Sudan). Does anyone know who the expert is on such things that I could contact to get confirmation, or do we have such an expert here on bird forum, or already on this thread, or is it likely I will never get complete confirmation from these photos?
Thanks

Tom

hello,

the bird is a young adult (most probably a 5cy = 4th cycle) - told by large apical spots (white primary tips). extent of pale bill tip varies as does the dark mark. armenian usually show a large (much larger) black mark on bill, adult cachinnans usually is more likely to show a dark mark to bill in basic plumage but this varies a lot and many adult michahellis show such a dark mark too, especially in younger adults (4th cycle). so this doesn't help. bill shape however is a good mark - usually long and parallel in cachinnans, less bulging at tip than in tom's bird. amount of black on upperwing can appear identical in both michahellis and cachinnans because the diagnostic grey tongues of cachinnans in outer primaries are usually not visible. in underwing however there are marked differences between these 2 species, YLG having much more extended black and tongues are shorter than in cachinnans:
mich: http://www.pbase.com/stephaubry/image/74435789
cach: http://lou.bertalan.de/gulls/m_phi.php?bid=183&grp=cachinnans adult alternate (january-june)
- some eastern cachs have more black, shorter tongues and black down to p4, p3 (nowadays considered to be a barabensis influence).
- some eastern (black sea) michahellis have less black in wingtip with rel. long white tongues but the majority looks like mediterranean birds.
the underside of wingtip is not well visible in tom's shots that's why i asked for this.
as for the mirrors: in an adult bird such a small p10 mirror with a solid subterminal mark and a very small p9 mirror usually is not found in cachinnans, even not in a 4th cycle. but steppe gull, barabensis, does. however, for a classic barabensis there is too little black on primaries: just a small p4 mark, perfectly fitting cach and micha at this age.

for fabalis: just a minority of eastern michahellis have an all white p10 tip (maybe 30%? while in western mediterranean birds this is only at about 5-10%)

as for likeliness: michahellis usually is more sedentary but disperses along large river systems (like the nile, so this could well be possible). cachinnans migrates further but usually not that far south/west? this doesn't give any clue.
last but not least, on jizz this looks like a yellow-legged gull.

Bump.

Any other opinions gull guys? People get all over these threads if it's a possible UK hybrid or atlantis or whatever and yet this first for its country thread is very quiet.

PS I'd agree that it doesn't seem to be a Caspian and looks like a Yellow-legged on jizz, but I'm not a primary counter type so my knowledge ends around about there.

Yes,Armenian gull for me,wing and bill pattern spot on.

PH

tom, when i wrote #8 i didn't realize you had posted the pic in #7. there's one hint i wanted to look for on the underside of outermost primary (p10). the shape of p10 tongue tip. in your gull it appears to be rectangular. this is a trait shared by taxons related to cachinnans, let's say in western and central asiatic taxa like cachinnans, barabensis or heuglini. some michahellis do have pretty rectangular tongue tips but a clearcut ~90% cut of the tongue is not common. usually tongue tip is rounded, bowed and, if in a clear angle, it ends in a steep angle to the edge of the inner web.

michahellis (attached pics):

(1) by odysseas tsimoulis, northern aegean. typical diagonal going tongue border.
(2) also by odysseas, northern greece, gallikos. this type with an clear angle but after that corner going in an angle more than 90° towards the outer edge of the feather. this type comes very close to the subject gull although it could be deceiving in the pic due to inclination of underwing plane.
(3) from black sea, romania (razvan zinica): very slight angle, small tongue.
(these 3 are rather typical ind., many have longer tongues or even inverted on tip)

cachinnans:

tongue tip similarly shaped like in (3) but longer (pic cristian mihai): http://lou.bertalan.de/gulls/pic/hi/up_0464.jpg

long and more or less round tipped (less frequent in cachinnans): http://lou.bertalan.de/gulls/pic/vh/up_0182.jpg (daniel petrescu, danube delta)

a recent pic (cris mihai): 4cy (3rd cycle) cachinnans with a rel. short but typically rectangular tongue. note that this age type 4cy-5cy could match the mirror pattern of your gull (small p9 mirror, p10 tip with subterminal band): http://lou.bertalan.de/gulls/pic/hi/up_1341.jpg

young adult/probably 5cy (4th cycle) cachinnans underwing pattern with rectangular tongue tip, just uploaded in "gulls" on BF (in the quiz section): http://www.birdforum.net/attachment.php?attachmentid=370243&d=1329680895


all in all i fear that if i was in a rarities commitee i wouldn't accept either of these from your pics, tom. i mean that it's not possible to be 100% sure it is a YLG from these pics. i can pretty much exclude armenian though. underside of wingtip has too little black for that taxon. an eastern cachinnans with bright yellow legs or a michahellis, or a hybrid cachinnans x barabensis - all possible.