24



Arthur G. Butler — Colour-change in Birds



pigment. On the contrary, I think the assertion that blue colouring

in birds is not due to pigment but to structural characters implies

distinctly that some other colours are due to pigment. I have never

yet seen it stated that feathers do not contain pigment; it is absolutely

certain that the scales on the wings of butterflies do, as anyone can

prove by soaking the wings of a Brimstone Butterfly in warm water

in which soda has been dissolved, when he will see the whole of the

yellow colouring precipitated, and the wing can then be dipped

into blue dye, which the scales will absorb (I have myself done this).


Because the red colouring in the wings of Touracous is stated

by various trustworthy naturalists to be soluble in water, and

especially in water more or less saturated with an alkaline reagent,

it by no means follows that other birds of red plumage must

necessarily be similarly affected. As I have pointed out, whereas

in the case of the butterflies the colouring of most scales is perfectly

soluble, other scales appear to be sealed up and do not release their

colouring ; it is conceivable, therefore, that the pigment in one

bird’s plumage may find its way out of the feathers, whereas in

another bird it may be strictly confined therein.


It used to be asserted that birds with red in their plumage became

dulled and even melanistic if fed upon hemp ; I proved to my own

entire satisfaction that this was quite a mistake. I kept three species

of Grey Cardinals ( Paroaria) and fed all three with a seed mixture

consisting of canary, oats, and hemp, upon which they did remarkably

well, and the skins of those which I preserved would compare very

favourably with the examples shot by collectors and now in the

National Collection.


I kept mealworms in a large tin with a mixture of bran, middlings,

and bits of old sacking, and I never knew the colouring of any bird

to be affected by feeding upon them. At the commencement of my

avicultural studies I used to put a dead bird, mouse, or piece of fat

into the mealworm tin ; the result of this was that I went one morning

to the tin and found an atrocious evil-smelling mass of putrescence

which I had to bury; the worms themselves were all rotten. If fed

regularly upon minced raw beef, I have found that most insectivorous

birds get a bad attack of diarrhoea, and if the same diet is persisted



