Chiffchaffs in south Portugal

By late December the south coast of Portugal is swarming with Chiffchaffs (Phylloscopus collybita). Sunny days around a reedbed can be very productive if you are interested in get familiar with plumage variation of these busy birds.
Some birds, with good light and the help of a camera, can be aged by the level of wear on wing feathers, and the presence of different generations. First winter birds will show more abraded flight feathers and usually diferent generations in coverts, being the result of a partial post-juvenile moult.
In the case of the bird in the picture, it´s possible to see that some tertials and the central pair of tail feathers was replaced on the post-juvenile moult. Although, from late December onwards we need to keep in mind that adults and first years usualy do a partial pre-breeding moult, and it could simulate first winter plumage, but this new feathers would be fresh!