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Lokalitet:
Skálafjørður / Eysturoy - Færøerne
2009-03-08
Fotograf: Rodmund á Kelduni - Se profil

Titel: 2cy Thayer's/Kumlien's Gull

Beskrivelse: Is this a first or second winter Thayer's Gull?

Uploadet 2009-03-08 Publiceret 2009-03-08 Larus sp. Gull sp.
14 6392
Kommentarer
Silas Kristian Krag Olofson
9. mar. 2009 kl. 13:26
Fuglen er pp i dag 9. marts ved Runavík, Eysturoy, sammen med flere hvidvingede måger, en enkelt gråmåge, en adult sildemåge, rider, sølvmåger, svartbage, stormmåger og hættemåger. Der manger sådan set bare lige en kumlieni i flokken.
David Erterius
9. mar. 2009 kl. 14:43
Congrats! It's a first winter individual. Or, actually it's still in complete or near complete juvenile plumage (same moult pattern as the other "Polar Gulls"). Note the juvenile head, body, mantle and scapulars.
Silas Kristian Krag Olofson
9. mar. 2009 kl. 15:01
Hi David That's also the conclusion we reached. The only thing which is a little tricky is the pale base at the bill, which I think should be entirely black. Silas
Jan Ingvaedt Jörgensen
9. mar. 2009 kl. 17:23
Hi Silas. A pale base to the bill, on both mandibles or just a fleshy smaller area at the base of the lower mandible at this age is not exeptionally unusal at this time of year A pale fleshy base on lower mandible, or on both mandibels, or half the bill on the upper mandible with only a small fleshy base on the lower,can be seen from late Feb. onwards, or more extreme, earlier in the end of 1cy. Was the impression of a very pale base as obvious in real life as on the image? Are there other images Silas? JanJ
Rodmund á Kelduni
9. mar. 2009 kl. 18:30
Hi Jan. No, in the field the bill semed all dark, but seen up close, it has a "palish" base on the bill, more "dirty gray palish" i would say. RáK.
Rodmund á Kelduni
9. mar. 2009 kl. 19:13
I have now uploadet two other images vere the bird is seen i flight. RáK
Silas Kristian Krag Olofson
9. mar. 2009 kl. 19:54
More pics of this bird can be seen here and here
Lars Witting
10. mar. 2009 kl. 01:24
After having seen several Thayer's-like 1th vinter gulls like this one here in Nuuk Greenland (see e.g. http://www.netfugl.dk/pictures.php?id=showpicture&picture_id=225), and realising that Kumlien's are most likely hybrid forms between Iceland and Thayer's gulls, I now think that it is almost, if not, impossible to distinguish a 1th vinter Thayer's from a very dark Kumlien's. To me this bird does though look like a dark Kumlien's (pale bill base, dark areas on tail and wings probably not sufficient dark, and apparent typical round Iceland/Kumlien's gull head shape, not elongated as, at least, in some Thayer's (see e.g. http://www.netfugl.dk/pictures.php?id=showpicture&picture_id=13266)
Jan Ingvaedt Jörgensen
10. mar. 2009 kl. 20:49
Whether kumlieni is a result of hybridization between glaucoides and thayeri has yet to be proven! However,it would be a lot easier, and perhaps more realistic if glaucoides x thayeri = kumlieni.The huge variation in kumlieni perhaps signals other than species/ssp rank. The in question here, looks better for thayeri than kumlieni - on structure, tertial pattern and bill structure, and question is, can a dark kumlieni look like this? One has to remember that birds with an intemediate appearance occur and whether they should be considered as individuals of either species/ssp being on the their dark or pale end of variability or hybrids (thayeri x kumlieni) is a matter of taste and knowledge, a knowledge we don´t have - yet. JanJ
Jan Ingvaedt Jörgensen
10. mar. 2009 kl. 21:07
Suppose you have seen these, some good images of varies kumlieni and thayeri. I´m not saying that these are all correctly identified, not mening to doubt Brandon - I know him as an experienced birder. http://www.peregrineprints.com/Gulls/ICGU_THGU.htm http://picasaweb.google.com/Paul.J.Hurtado/17Jan2009 JanJ
Lars Witting
11. mar. 2009 kl. 11:45
I guess it is true that it is not proven that kumlieni nessensrily is a hybridisation form between glaucoides and thayeri; but nor is it proven that it has species/ssp rank. What is known, however, is that kumlieni interbreed with both glaucoides and thayeri, and that kumlieni forms occur almost as a continium from glaucoides to thayeri (most likely as a consequence of back crossing to both sides). Also consider what happens if we accept the species/ssp rank of kumlieni: with interbreeding two both sides it becomes, I would say, impossible to distinguish a kumlieni from a hybrid!!
Rodmund á Kelduni
20. dec. 2009 kl. 23:34
This bird was not accepted as Thayer´s gull by the Danish Rarity Commitee, however it is accepted as Thayeri/Kumlieni, since the bird show´s intermediate caracters for thayeri and kumlieni. I wisited the BBRC (British Birds Rarities Committee)site http://www.bbrc.org.uk/, and i must say, i got confused. On the BBRC rarity list http://www.bbrc.org.uk/currentrarespecies.htm Thayer´s Gull is listed as a sub-species (LARUS GLAUCOIDES THAYERI) The Danish Rarity Committee usaly follows the BBRC, but they list Thayer´s Gull as a species (Larus Thayeri)
Sebastian Klein
21. dec. 2009 kl. 08:41
Hi Rodmund As far as I can remember (this was all decided some years ago) the Danish RC decided to Follow the American Birding Association as there were no records from Britain and therefore no taxonomic recommendations from the BOU on this particular (sub)species. To my recollection Thayer's Gull has been recorded in the following Western Palearctic countries: Denmark, Norway, Iceland and Ireland. All these countries have Thayer's Gull listed a a full species. Britain has had a few Thayer's Gull-claims and it is not inconceivable that a British record will be accepted at some point in the future. If the BOU recommends that Thayer's Gull is to be considered as a subspecies the DRC will probably reconsider the taxonomic status of the Danish record.
Rodmund á Kelduni
21. dec. 2009 kl. 19:08
Hi Sebastian Thank´s for pointing this out it is surtently a diffecult task and hopfully it will not be too far in the future.

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