Ring-billed Gull uneven tail growth

[Morg]

I photographed this individual Ring-billed Gull at Nimmo's Pier in Galway, Ireland, in December 2010 and again in January of 2012. I gather that it is one of the regular birds at the site. It has a small number of recognisable features in the various photographs that I took from the two years (e.g. bill band shape and size, extent of head streaking) but most intriguingly it shows exactly the same uneven tail growth on the two dates (the following 2 photos allow the best comparison of the tail shape).

Anyone seen this kind of thing before? I am assuming that the tail feathers are different ones, unless moult has been suspended and the feathers have been very well looked after...

Geoff

Ring-billed Gull, Nimmo's Pier, Dec 2010

IMG_5823.jpg (34KiB)Viewed 2453 times

Ring-billed Gull, Nimmo's Pier, Jan 2012

IMG_5859.jpg (28.1KiB)Viewed 2453 times

Don't be put off by the similar jpeg numbering - these shots were taken 12 months apart.

[marsmuusse]

Hi Geoff,
Funny thing you noticed here. As it seems it is the central left feathers falling short, I doubt this bird has suspended moult. Normally the rectrices are replaced 'centrifugal', with R6-R5 the last to be replaced, and these central feathers to be dropped first. In this bird, R5-R6 seem to be of typical length?

Mars