Bird, taxidermy specimen, Brambling (Fringilla montifringilla) from
Bramblings are a migratory finch, common in the UK from September to March. Although very similar in habit, size, and shape to Chaffinches ('Fringilla coelebs'), Bramblings seek out beech mast (beech tree nuts) during the winter to avoid competition with their close relatives.
This taxidermy specimen is leucistic, meaning that its plumage lacks most of the melanin pigment that produces browns and black, whilst carotenoid pigments, responsible for yellows and oranges, are unaffected. Abnormal pigmentation such as leucism and albinism can result in weak feathers, which are more prone to wear. This can hinder flight, as well as making the birds more conspicuous to predators. It can even affect recognition by potential mates
The Victorians were fascinated by unusual forms of wild birds, and these examples fetched higher prices than the 'normal' specimens. Museum taxidermy collections dating from the 19th century can sometimes contain more unusual colour-variants than the usual forms we are used to seeing in the wild.