DOES DIET AF­FECT A BIRD’S COLOUR­ING?

Bird Watching (UK) - - Your View -

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.

Whooper Swans

Newspapers in English

Newspapers from UK

© PressReader. All rights reserved.