(note careful positioning on same branch as the male!)
(looking the same as nearly all other male Greenfinches)
Sometimes, however, you get one that you can see is different from a distance. Occasionally they might have a white feather, or a distinctive injury. Very occasionally you get a true colour variant, such as an albino (white), melanistic (dark) or (in the case below) leucistic (lightly-coloured) variant. These colour variants occur in most species, albinism being probably the best known (you can even get albino humans). Albinos have no melanin to colour skin, hence they are white. Leucism is rather different in that all skin pigments (not just melanin) are present, but at reduced levels. Again, leucism occurs in a variety of animals and are generally described as being the colour of milky tea (or "tay" as its called locally (you see - cultural enlightenment as well as peals of birding wisdom)).
(affectionately known by me as Lucy)
|Bog Standard Greenfinch (top left) and Lucy|
(and a Starling's tail top right!)