“Leucism resulting in xanthochroism” – A report on colour aberration in Coppersmith Barbet Psilopogon haemacephalus from Asia

Plumage colouration is important for birds as it helps them in camouflage, mate selection, social signalling and various other physiological and behavioural processes. The most common pigments responsible for colouration are melanins and carotenoids. In a few individuals, colouration is disrupted due to various causes. The most common colour aberrations found in birds are leucism, albinism, melanism, carotenism, schizochroism and dilution whereas xanthochroism is a lesser-known phenomenon. In this article, five records of colour aberrant Coppersmith Barbet Psilopogon haemocephalus are reported. The authors along with the help of citizen scientists observed four individuals with disruptions in plumage colouration from different areas of West Bengal and Assam, India and one from Rajsahi, Bangladesh. Due to the lack of melanins, the birds were mostly yellowish and whitish in colouration with or without some normally coloured feathers on the head and wings. The carotenoid deposition was unaffected in the case of the observed adults and juveniles. These records can be cited as xanthochroistic individuals resulting from leucism. This is the first record of such colour aberration for Coppersmith Barbet from the whole of its distribution range.