158



Colour-change in Feathers



both insectivorous and seed-eating birds require a certain amount of

live food, which itself has lived upon live plants. They absolutely

require this a few months before the moult sets in. I have tried this

on Orange Bishops in conjunction with feeding on unripe seed, such

as millet or grass-seed still in a milky state. I almost got back the

original scarlet colour ! Bed-breasted Australian Bobins fed upon

mealworms exclusively produced a dirty pink after the first moult,

others which received in addition to the ordinary soft bill food minced

raw beef became almost white, which shows that the mealworms fed

on dry vegetable matter like bran will not produce the natural scarlet

in the feathers. During my experiments with the Sanguineous

Honey-eater (Blood-bird) I allowed some of these to fly in a large

outdoor aviary set with grape-vines and other plants, which attracted

myriads of the tiny leaf-fly. The flies served the Blood-birds as food

in addition to the sugar-water they received. All these birds moulted

perfectly into their natural scarlet plumage. At the .same time others

were placed in a large cage with plenty of sunlight, and fed on sugar

water sprinkled only with dried and crushed cocoons of flies and with

powdered flies. The birds did very well on this diet and moulted

without trouble—but a washed-out pink ! This seems to prove that

it was the leaf-fly in conjunction with unlimited sunlight which caused

the natural colour to reappear.


“ It is a remarkable fact that even in nature these colour changes

always affecting the red pigment may take place unconditioned by

age. I have seen in Fiji numbers of yellow-headed Parrot Finches

flying with flocks of red-headed ones, the true colour of the species.

1 have had young ones of this species which eventually moulted out

vellow-headed, neither is it an uncommon thing to see yellow- or copper-

headed Gouldians—the offspring of either black- or red-headed ones ;

and I may state here that I received for several years running a silver

white Galah, whose brothers and sisters out of the same nest were

naturally coloured. I think I am safe in saying that it is only the scarlet

which undergoes these variations, but where the actual cause lies is

still a mystery to me beyond what I know of experiments. The

common Blue Wren, for instance, which breeds freely in my aviary,

has always produced young which colour out according to nature,



