tirsdag 15. juni 2010

2cy Lesser Black-Backed Gulls again...

I'm still fascinated by the variability of 2cy LBBGs. At times it is difficult to believe that two individuals standing side by side belong to the same species...Here are pictures of 5 different birds, all from Fredrikstad, Østfold the first week of june. See also an earlier entry here:

A small and delicately built individual and most likely a female. Mostly (2. gen) ashy grey upperparts with a broad, diffuse shaft streak on mantle/scaps and anchor-patterns on the coverts. Juvenile flightfeathers and rectrices. Very likely intermedius from the local population(?).

Individual #2
A completely different individual with pale grey mantle and scapulars with distinct anchors - a feather-pattern reflected in the renewed coverts.
Contrasting in flight, very reminiscent of an autumn/early winter michahellis. In this individual the head/bill - shape adds to this similarity. Note also the rather conspicuous window on the inner primaries, a feature many spring 2cy LBBG's show up here, probably due to wear.

3 central pairs of rectrices renewed but juvenile primaries (P1 dropped) and secondaries.

Primary window again..To me, this was a confusing individual, but I have later received feed-back from Ruud Altenburg, Holland, stating that this is a fairly common type of 2cy LBBG. There you go..

Individual #3
A big, heavy-billed LBBG, most probably a male. It was very aggressive and didn't hesitate to attack GBBGs and fight them for food. This bird had mostly slaty grey mantle, scapulars and new coverts (best seen on the flight shots) and is much purer white on the head and underparts than #1 and #2. The underwing is also predominantly white where the preceding birds where heavily marked.

P1 growing, P2 dropped, rest of flight feathers juvenile. Central pair of rectrices renewed.

Individual #4
A huge and mean-looking individual with pale, slate grey new mantle, scapulars and coverts. Very similar to #3 with which it was seen side by side, but bigger and with paler grey plumage.
P1 dropped, rest of flight feathers juvenile (and note the inner primary window on both #3 and this bird). Central pair of rectrices renewed.

Even whiter underwings than #3.

Individual #5

A small individual that unfortunately was only observed and photographed (well, sort of..) from a very long distance. The photos don't offer much, but it is visible that the bird had a full set of new primaries and secondaries. The entire tail was also renewed. This is of course indicative of fuscus, but heaven knows with these birds...

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