DOES DIET AFFECT A BIRD’S COLOURING?
Greater Flamingos do indeed obtain their pink feather colouring from their food How does food colouring affect a bird’s feathers, for example in pink flamingos, when I thought feathers were made of ‘dead’ keratin? Heather Rowe, Portsmouth
QFeathers are indeed made of ‘dead’ keratin, in that they have no nerves, no blood supply, and no way of healing themselves if damaged. However, just like the hair of mammals, they start off as living cells; otherwise they wouldn’t be able to grow at all! It’s during this growing period that pigments are deposited into the feather. In the case of the carotenoids that give some birds their red, yellow, orange or pink colouration, the pigment can only be obtained from food, hence the old practice of using paprika to manufacture ‘red’ canaries. These carotenoid pigments are extracted from the food, and sent to the
Abird’s liver, where they enter first the bloodstream, and then the follicle from which the feather grows. From there, the pigments enter the feather’s cortex, and then the barbs of the feather as they grow. If a bird loses access to these carotenoids, the bird will change colour at the time of the next moult, as new, unpigmented feathers push out the older coloured ones, although feather wear and fading due to age and light might make the process appear more gradual. This food-related colour change only seems to work with red pigments; green pigments from food seem to be digested in a different way, and don’t seem to be able to influence feather colour at all.