I have seen a young starling in my garden with a white cap to it's head, and some modest white leading edge of wing bars.
Reading in my old Birds of Britain and Europe (Peterson et al), there is no mention of this variation, but I have yet to consult my other books (Work has been unrelenting). I wonder if this is a degenerative colour variant, or whether it is a new mutation, which may die out soon.
Thank you. So you are suggesting that all the melanocytes are missing?
Or are you talking of albinism, where there are melanocytes, but they can be amelanotic?
Whatever the case, that refers to the result or phenotype, but not the aetiology or genetics. I wonder if this happens as a mutation, which dies out because the birds are predated more readily, or are more outcast by their fellow birds.
Is the phenotype transient like the tabby appearance in black kittens which gradually fades, or does it stay?
I may sound as if I'm being critical, but I'm not; I'm curious to know what the background to the appearance is.