This bird (3 images) is very pale and frosty with a sizable white and black streaky rump and a single undertail covert streak. Surely this is a Common Redpoll Ssp?
This beast was seen last week and is surely not of these parts! Compared to Lessers (little brown birds!) it was huge, cold and grey. Could this bird's home town be Reykjavik or Nukk? Certianly not Bangor!
Then we have this male below. It has replaced five inner greater coverts that are boldly tipped white and still it has four or five immature narrower and slightly darker tipped coverts. The folk in the camp of saying that 'the coverts become whiter with age' cannot make the suggestion here. There is clearly a moult limit in the coverts, and the newer feathers are tipped much broader and whiter (this is normal in finches for the newer adult feathers to be tipped broader), they are therefore younger than the darker ones and cannot have been bleached with age. Still, this bird has a rather dark looking mantle, but was a hefty bird, is this a NW first summer male?
This bird was seen from the kitchen window yesterday, big bold white and black rump and tramlines, white wing bars and very silvery on the nape. Again note the moult limit in the greater coverts, where the newer adult feathers are boldly tipped white and the immature first winter feathers have a brownish stain to them. Not sure what it is really, but not a local lad for sure!
You can see the moult limit on the first winter exilipes Arctic Redpoll that spent the winter at Titchwell in Norfolk. The newer adult type feathers are longer, with broader white tips. The paler parts of a bird's plumage contain less pigmentation, so as a result these parts of the feathers are weaker than the rest of the feathers and wear much more rapidly. If feathers were 'bleached' one would expect them to be wearing and breaking up (like some first summer two-barred Crossbills lacking the pale tertail tips due to them wearing away rapidly, and the white tips on a Goldfinches tail dissapearing within months of them leaving the nest). I think what I am suggesting is that the paler parts of the wing bars on these birds are not bleached, but are genuinely paler. If we look on BirdGuides at some obvious adult Lesser Redpolls, then the wing bars on many of these are of a single generation of feathers and are completely buffish and not white.