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Thursday, 10 January 2013

Wing formula and future ID.

The top two shots from Cardiff Bay taken on Feb 8 2010.
Note the outer web of the 2nd primary of the left wing has a very slight, hardly noticeable black streak, whereas the 2nd primary on the right wing is more obvious.

The Ogmore bird`s left wing`s outer web of the 2nd primary is very obvious ( as Dave Rich pointed out on the GBC) with no evidence of any marks on the right wing.
So it is a different bird to the returning Cardiff Bay bird! This would then be approaching full adult plumage, as would the Cardiff Bird.





6 comments:

Mitch said...

Nice stuff! i must have been looking the other way when it was paddling.

Phil B said...

Interesting thoughts Steve. Your conclusion that the Ogmore and Cardiff bay birds are different individuals assumes that feaures, such as black streaks in the outer pps, are constant once acquired. The Cardiff bird of previous years will have moulted out its pps once annually and whether the replacements are identical to those dropped, who knows? That said, the Ogmore bird will at least retain its current pps through the rest of this winter and spring, so if it moves eleswhere the photos should enable it to be compared. By the way, has anyone compared the pics of the Ogmore bird with the one recently in South Devon?

Joek Roex said...

Maybe we should try and age these birds. Like Black-headed Gull Bonaparte's Gull is a two-age group gull, i.e. adult plumage is assumed by 2nd cal. moult beginning with 2nd w. If the 2010 bird had just moulted into ad. plumage, it must have been born in 2008. Could this be an explanation of the remnant of the black of a previous plumage on p9 on both wings. If the Ogmore bird is the same individual, it will now be 5th cal. and more of the remnant black will have disappeared.

Steve Hinton said...

Exactly my thoughts Joek!
A quick look for pics of the Dawlish bird also shows primary streaks on both wings. Rules out Ogmore bird!

Phil B said...

Agree Steve, the few images of the Devon bird I have since looked at indicates separate individuals. I'm unconvinced pp patterns will allow us to safely link or dismiss the Ogmore bird as relating to previous sightings in Glamorgan in other recent years. But the quality of the images gained in the past week will surely help if this bird moves on and is found and well-photographed elesewhere before its next complete moult.

MauriceC said...

Don't forget the feathers will be subject to wear as the winter proceeds.