Hvis man skal holde fast i, at der blot skal være nogle "spøgelsesskygger" på primærerne for at kvalificere en fugl til ssp. kumlieni, så der denne en klar kumlieni. Man kan sige, at det er en 1 % "ikke glaucoides" i den, hvor en fugl, der ligger ultra tæt op ad Thayer's Måge vil være en 1 % "ikke thayers".

Til at underbygge, at det faktisk er en ssp. kumlieni kan nævnes, at iris er ret mørk (typisk lys hos 3k glaucoides) samt at der er tydeligt mørkt halebånd og at fuglen virker kraftig.

Men denne fugl understreger meget nydeligt, at hvis man godkender disse meget blege fugle med minimal tegning som ssp. kumlieni, så er der rigtig mange fugle, der faktisk ikke kan bestemmes i felten - de skal simpelthen fotograferes, før man kan være helt sikker på, om der er tegning eller ej.

Men det korte af det lange er, at jeg vil kalde denne en minimalt tegnet kumlieni ud fra ovenstående.

Strictly speaking, kumlieni refers to the “population” of Iceland gulls that breed mainly on Baffin Island. They are known to interbreed with Thayer’s in the range of overlap, and we have found a couple of kumlieni-like X glaucoides breeding pairs here around Nuuk, Greenland. It is therefore of no surprise that we during winter can see birds of basically the full continuum from glaucoides to Thayer’s. Only some of the intermediate collared birds are likely to be pure kumlieni; the lighter birds almost certainly have some fraction of glaucoides in them, and the darker some fraction of Thayer’s. This makes it basically impossible to decide when a kumlieni-like bird outside the geographical distribution of kumlieni is a pure kumlieni, and my first-hand judgment would be that none of the birds seen in Denmark this winter is a pure kumlieni (they are too much in the lighter range). I also personally find it impossible to decide when a very dark kumlieni-like bird here in Nuuk (typically a 1 or 2k) is a Thayer’s, and not just a hybrid (if I would now ever try to identify a Thayer’s in Nuuk it would most likely be by its Jizz). The only type of these gulls that are clear-cut to identify seems to be pure glaucoides, and this is probably why we falsely in my opinion (my-self included) tend to label kumlieni-glaucoides hybrids as kumlienis.

Bolden er hermed givet videre til en spændende diskussion. Kumlieni regnes jo som en hybrids ørn mellem glaucoides og thahæl. Den er stærkt variabel, og anvendes den traditionelle definition: St kumlieni er en hvidvinget måge med velfrfinerede tegninger i vingespidsen er der vitterlig en del i omløb lige nu.

Ìg kumlieni, as traditionelle regarded is a hydrid swarm between glaucoides and thayeri, a kumlieni is a glaucoides with defined wingpsttern. That all birds this winter gave been paler end og the variation probably mirrors their origin in areas mot too far from Greenland

Having studied this interesting phaenomenon while preparing Guils I am sorry to be offline most of the next 10 days.

It all comes down to definations I my humble opinion. If we regard kumlieni as all the integrades between a pure thayeri and a pure glaucoides then birds as these very pale ones should be labeled kumlieni. And then a hybrid between a kumlieni and a glaucoides would produce a kumlieni - but over time these could be very hard to identify if lets say a pure glaucoides interbreeds with a kumlieni x glaucoides in several generations. And maybe this is in fact what we see with all these pale birds now.

Another aspect then is if there pale birds really are the genuine Baffin Island breeding birds or if the birds from Greenland can show some variation when it comes to ghostly patterns on the primaries. That could probably only be found out if we follow some of these birds during their ageing.

Lars: What do you mean by a "pure kumlieni"? If kumlieni as generally believed are hybrids of Thayer's and Iceland gulls, there are no such thing as a pure kumlieni, unless you mean first generation hybrids between pure Thayer's and pure Iceland gulls, such individuals are probably quite rare and impossible to separate from other intermediate individuals with roughly 50% genetic material from each?

Thanks Jan. Yes I should have added that my comment was based on the assumption that there is a “self-sustained” population of kumlieni (a subspecies), and this might indeed not be the case. It is quite likely that kumlieni has originated as a hybrid-zone between Thayer’s and glaucoides, and this raises the question whether the population of kumlieni on Baffin Island today is “self-sustained” or still a hybrid-zone. If it is still a hybrid-zone we might expect that individuals of kumlieni have a lower fitness than individuals of both Thayer’s and glaucoides, and that kumlieni would disappear over time if we removed either Thayer’s or glaucoides. In other words, kumlieni would exist only as an evolutionary battlefield between Thayer’s and glaucoides. If on the other hand, the population of kumlieni is “self-sustained”, it could continue to exist even in the absence of either Thayer’s or glaucoides. In this case the population of kumlieni would have two “hybrid-zones”; one with Thayer’s and one with glaucoides. In between we could expect a population of pure kumlienis to exist. This refers to my comment above, which is the logical consequence of the very classification of kumlieni as a subspecies. If instead the population is a hybrid-zone, we don’t really have a subspecies (at least I would say) because all kumlieni individuals would be hybrids (on a continuum from Thayer’s to glaucoides).

In relation to identification the two cases are also quite different. With a subspecies to check, we have the problem that it is almost impossible to identify pure kumlienis. With a hybrid-zone it is instead quite easy to identify kumlienis because all birds between Thayer’s and glaucoides fall in this class. But then we would not have a subspecies to check. So put a little bold; we either have a subspecies we cannot identify, or we have a hybrid we can identify. But today it appears to me that kumlieni is classified as a subspecies (correct me if I am wrong here), but that we identify them as hybrids (i.e., for adults, if primaries are not fully white, then, it is a kumlieni).

I hope this clarifies – Best - Lars

Er problemet ikke at disse hybrider på et tidspunkt fejlagtigt har fået en latinsk betegnelse, ssp. kumlieni, som man så forsøger at tilpasse dem ud fra?

Further on the subject with pic. here
and here

JanJ

...also here

JanJ

samme fugl ses fra her fra den 4. februar. den kan kendes på den lyse kile, der strækker sig ind i den mørke næbspids bagfra foruden svingfjerstegninger og springet mellem hånd- og armsvingfjer, hvor de inderste håndsvingfjer er slående korte i forhold til de yderste armsvingfjer

henviser til de ekstra billeder, da diskussionen har omhandlet, hvorvidt fuglen har karakterer svarende til en lys kumlieni

hov, belager, det er denne fugl jeg tænkte på