xl 



INTKODUCTION. 



Mr. T. W. Kirk has described a Ground Pipit (Anthus novcB-zealandice) which exhibited 

 both melanoid and albinescent tendencies (see footnote on page xlii. of Introduction, vol. i.). In 

 the ' Birds of New Zealand ' I have recorded albinoes, more or less perfect, of thirty-three species 

 (see enumeration, I. c, p. xlii.), and in this ' Supplement ' I have added eight more. I am informed 

 by Mr. Walter Eothschild that he has received a pure albino of Thinornis novce-zealandicB from the 

 Chatham Islands ; also an entirely white (Estrelata coohi S , obtained off Stewart Island, and an 

 example of Himantopus melas, in dirty-white plumage, with only a few black feathers on the 

 upper surface. 



It is, of course, the pigments in the feathers which produce the colours that we admire so much. 

 Dr. J. S. Kingsley, in an excellent article on the subject, informs us that " a colouring matter 

 which is called zoomelanin, and thought to be identical with coriosulphurine, seems to produce 

 all the black and dark hues in birds, while some green colours are due to an admixture of 

 yellowish pigment called psittacofulvine. A really green pigment has pnly been found in the 

 Touracoes— hence the name turacoverdin — and no blue or violet pigment has yet been discovered, 

 while red (zooerythrine) is quite common. Another red, turacin, causes the magnificent red on 

 the wings of the Musophagidce. There is no white pigment, but wherever that colour occurs it is 

 due to the countless number of interstices between the molecules of the feather, the substance of 

 the latter being colourless. Many tints— for example, blue, violet, and certain greens— are not 

 due to the pigment, which is black-brown to yellow, but the blue results from a particular surface- 

 structure of the feathers, so that it must disappear if the colour-producing parts be destroyed. 

 Thus, if we hammer carefully the deep-blue feathers of a Macaw, the blue colour immediately 

 disappears, and the injured part looks grey or brownish, according to the underlying pigment. 

 Some green parrot feathers, when treated in a similar way, become yellow, since this is the 

 colour of their pigment." We are told that the gloss of feathers, independent of the colour 

 itself, is the result of their surface being smooth and polished, while the metallic lustre is 

 due to a transparent sheath which acts like a prism. 



Closely connected with this subject is that of " dichromatism." Of this colour-problem the 

 same author says : " We are accustomed to call it dichromatism, but of its true nature and its 

 significance in the animal economy we are quite ignorant. By this term we designate the 

 peculiarity, in certain species of birds, that individuals present two different styles of coloration, 

 or ' phases,' presumably more or less independent of geographical distribution, present or past, or, 

 in fact, of any apparent cause whatsoever. The difficulty in finding a plausible theory is much 

 increased by the circumstance that there are nearly as many kinds of dichromatism as there are 

 dichromatic species." Among the examples put forward by him is that of the dark and white 

 forms of Ossifraga gigantea. In this I think he is mistaken. I have, from time to time, recorded 

 seven examples of the white Nelly from New Zealand waters. Of these only two were 

 absolutely pure albinoes. One of them, which I obtained at Waikanae, about forty miles up 

 our Wellington west coast, and presented to the Colonial Museum, was of snowy whiteness, 

 without blemish of any kind, even, the legs and feet being whitish, whilst the bill was yellowish 

 horn-colour. The other, which is almost as pure, was obtained at sea, about ten miles north 

 of Milford Sound, and presented to me by the late Captain Fairchild. All the other examples 

 are more or less marked with dark feathers, scattered irregularly over the entire body. There are 



Dr. Hartert called attention to the vital difference between true albinoes, which were born white, and in which the total 

 absence of pigment extended also to the iris, which thus became pink, and " pied " or partially white plumaged birds, 

 which had in many cases been at first clothed with a perfectly normal plumage, and in which the partial absence of 

 pigment sometimes appeared after several moults, and was not always quite constant. 



For a case of progressive reversion from partial albinism to the normal colour, see my account of Cyanorhamphus 

 auriceps ('Birds of New Zealand', vol. i, p. 142). 



