on the Bleeding of the Crossbill. 113


moult and to be lost the next season. Unless I am mistaken,

both the Scarlet Ibis and Flamingos lose, to an extent, the depth

of tone relating to their pinky hues ; but I can obtain no in¬

formation concerning the moulting in captivity of a Roseate

Tern. The beautiful rose tints in birds of this kind have always

captivated me; but I cannot convince myself, owing to numerous

contradictions that its presence or absence entirely depends upon

food. The red crimson and rose feathers of such birds as

Weavers, Cardinals, Tanagers, Goldfinches, Gouldian Finches

lose nothing when they are properly moulted in captivity. In

the case of Pyrrhula enropcea it is true that the colouring of the

breast feathers seems less stable ; on the other hand, a discreetly

fed and naturally rich-toned bird will retain its beauty for years.

Zoonerythrin seems to be the colour pigment affecting red

feathers in birds, and I am inclined to think it exists in its most

unstable form in the case of those species that have pinky or

rosy tones in their plumage. This change, which occurs usually

after a moult, in no way disturbs the general health of the

creature, or lessens its powers of propagation, and the only

partial explanation that suggests itself to me is that these altered

conditions are not conducive to the normal distribution of pig¬

ment in the course of new feather-building. Although the

superstructures may be altered but little, a disturbance is set up

in the formation of these highly unstable materials. New colour

pigments may be built up, or a natural pigment may disappear

and its place may be taken by an abnormal one. Possibly, with

such birds as the Linnet and the Scarlet Rose Finch (Carpodacus

erythrinus) a condition arises in which an abnormal amount of

Zoomelanin is formed,which, fused with the natural Zoonerythrin,

forms a brown or rusty area instead of a crimson one. I11 the

case of Crossbills, Sepoy Finches, and “ brassy”-looking Redpolls

Zoonerythrin seems to disappear, and possibly Zooxanthiu is

formed, or a green compound, due perhaps to mixtures of yellow

and greyish-brown pigments. White birds, such as Snow Bunt¬

ings, seem to develop a much more stable form of pigment in

captivity, and Lapland Buntings usually reach quite a ripe age

before their black becomes well developed.


Allowing for seasonal changes of plumage and wear and



