Letters


Dear Parrots magazine,

Feather Facts and Feather Fiction

I am in total agreement with Sally Blanchard’s comments in her article “Healthy Feathers” in April’s edition of Parrots magazine, that nutrition through a good diet has a profound effect on the quality of feathers. But some facts seem to have got muddled when it comes to diet and its effect on feather colour in parrots.

It is possibly easiest to address the confusion by reviewing the basics behind feather colour. Feather colour is produced by two basic mechanisms, colour pigment and feather structure and the colours we perceive in birds is invariably a combination of these two mechanisms.

Colour pigments come from two sources; those contained in foods and those made within the body, or more specifically in the case of birds, exclusively within the feather follicle. For certain species of birds, dietary colour pigments called biochromes (of which there are many) are ingested and then deposited either unaltered or modified into the growing feather. Classical examples of these are the yellow colouring of canaries and the pink feathering of flamingos. Manufactured pigments comprise amongst other colours, the various ‘shades of black’ produced by different forms and concentrations of melanin pigments. These range from the dark black of crows, through brown sparrows, olive-green greenfinches and even the rusty-red of a robin’s breast.

Melanins are common to all birds, but another group of manufactured colour pigment called psittacofulvins are unique to parrots. It is these manufactured pigments, along with varying shades of black and grey, that are exclusively responsible for the colour pigments in the feathers of parrots. Contrary to what the article suggests, dietary carotenoids do not directly influence the colour of your parrot’s feathers. You will not increase the level of red or yellow in your parrot by increasing the amount of red or yellow in their diet – it is not how parrot feathers work!

So what of the story of the colour change in the Cockatoos? The increase in the pink colour of the Moluccans’ feathers described in the article can almost certainly be attributed to increased levels of beta-carotene and other carotenoids in the diet but not as a consequence of direct feather pigmentation as Sally infers. The big benefit of feeding diets with high levels of carotenoids (coloured fruit and veg) is that carotenoids are natural antioxidants used in biochemical reactions throughout the whole body. These antioxidants are required and utilised by the feather follicle to successfully manufacture the red psittacofulvin, which gives the Moluccan its rosy hue, a process which they are unable to perform when the diet is deficient.

What of green, parrots do not possess a green feather pigment as implied by Sally, and blue feather colour in parrots? These are tricks of the light and a story that can wait for another day.

Dr Brian Stockdale BVM&S MRCVS
Associate Lecturer Nottingham Veterinary School (Avian Module)


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