We have several blackbirds visiting our garden as well as a high magpie population. We have around three different blackbirds which have odd white feathers or white patches, making them look like they have large snowflakes on them. Does anyone know -Is this a common occurence in the breed ?
Leucism (abnormal white or pale plumage due to a lack of melanin pigment) can occur in any bird species but does seem to be particularly common in Blackbirds. It is caused by a genetic mutation so it's not unusual to find several affected birds in the same area, they are probably related.
Pigment loss can also be caused by a dietary deficiency but that tends to affect just the middle parts of the long wing and tail feathers, it's very common in urban Carrion Crows (like this: http://www.thamesvalleybirds.co.uk/attachments/bird-photos-general/13086d1268840091-leucistic-crow-dsc_0067.jpg). Genetic leucism produces more randomly distributed white patches and in some cases completely white birds.
The BTO are conducting a survey of garden birds with leucism and other abnormalities, if you'd like to take part you can find the survey here: http://www.surveymonkey.com/s/plumagesurvey
My blog: http://mazzaswildside.blogspot.co.uk/
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In reply to aiki:
Reply deleted, I thought Aiki was back, didn't realise it was an old post!
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