The dark side of birds: Melanism-facts and fiction

Abstract

Melanism is generally defined as an increase of dark pigment in the plumage, resulting in a blackish appearance. Furthermore, melanism is often associated with mutations of one gene that encodes the melanocortin 1 receptor (MC1R), a protein involved in regulating melanin pigmentation. However, there is often no increase of pigment and melanism does not necessarily involve dark pigment alone. Also, many different mutations in many different genes promote melanism, which may explain why it is the commonest colour morph in birds. In the past, melanistic birds were sometimes mistakenly named as new species. Ironically, it now appears that melanistic birds do indeed differ from their normal-coloured conspecifics in more than just colour.