Any colour you like

Pigmentation in wild and captive birds

source: Tim Birkhead
Independent Review February 10 2003 p12

Humans have long sought to change the colour of birds, from when they were initially domesticated. Pigeons and geese were the first to be domesticated, some 5,000 years ago, followed by chickens. Birds might appear that lacked pigments. Colours might be changed through mutations, or through long-term gradual change. Yellow canaries were gradually developed, and full yellows were recorded by 1700. There are some 30 colours variations for budgies, which are green in the wild. Zebra finches have also been bred with different colour variations.

Dyeing birds was once common, whether by dyeing feathers externally, or by feeding birds such as canaries red peppers when the birds were moulting. Carotenoids can affect the plumage of wild birds, and are found in shrimps and other foods. Captive birds deprived of carotenoids they would eat in the wild can lose their bright colour. A bright red colour may signal good health in some species, especially in a male bird, and females of these species prefer redder males.