Once again, the area was finch-less, but never mind, on a patch there is always something of interest to watch.
Today it was a feeding flock of 70-80 Carrion Crows, which is a reasonably good size of flock for this species. These birds will probably be a loose association of birds without territories, and quite possibly would include a good proportion of 2nd calendar year birds.
Of these birds, I would estimate that somewhere between 5 and 10% showed clear signs of feather de-pigmentation (leucism) in their flight feathers. I am not sure whether this is a typical figure for this type of flock or whether the prevalence is higher at certain times of year or among birds of certain ages. Once I started looking it seemed that this flock contained an example of just about every pattern of feather de-pigmentation that I had seen in Carrion Crows before, from isolated asymmetrical patches, symetrical white flashes on parts of the wing, full broad white wing-bars through to almost fully white wings as in the bird shown above.
The next five pictures show five other birds from the same flock with different extents of de-pigmentation. Note that the bird shown above also features in one of the the photos below, and the photo to the right also shows a more normally plumaged bird.
Finally, here is another Carrion Crow from the same flock. Most of the de-pigmentation on this bird is not visible when the bird is feeding.