BIRDS OF NEW ZEALAND. 29 



feathers is regulated by the regions in which they Uve, the tendency to 

 melanism being chiefly noticeable in the southern hemisphere, and par- 

 ticularly in New Zealand, M adagascar, and New Guinea. The Swan furnishes 

 a marked example of this, as its white plumage of the northern hemisphere 

 becomes of a pure raven hue in Australia ; while in Terra del Fuego and the 

 adjacent portions of South America some of the wing-feathers only are black ; 

 and in Chili the head and neck are alike jet, the remainder of the body 

 remaining snow-white. This is again visible in the Perroquets in New 

 Zealand, their plumage showing only small portions of bright red and yellow, 

 and the rest being of a dingy green, deepening into black ; while the same 

 species in those islands of the Pacific near Africa display similar signs. In 

 Madagascar and the Mauritius, the Seychelles and the Comoro Islands, black 

 Parrots are frequently met with. Other examples, such as Ducks, Kingfishers, 

 &c., can be easily quoted ; and it has been found that, in the Southern Indo- 

 Pacific region, those birds which elsewhere present the most brilliant colours 

 are either there darkened to black or fade away to white." 



New Zealand presents many examples of the latter; and Dr. Buller 

 mentions its occurrence in eleven species. Diff"erence of colour, produced 

 by climatic change, is a long subject. We can always tell a bird which has 

 just landed at Brighton from one of the same kind which has passed the 

 winter here, from the superior freshness and brightness of its colours. I 

 have examples in my own collection to show this distinction. It is an 

 interesting topic, on which I could be tempted to run off, but must not. I 

 may, however, mention that there are several ways by which changes in the 

 appearance of the plumage of birds may be produced. Owen gives them as 

 follows : — ■'' By the feather itself becoming altered in colour ; by the birds 

 obtaining a certain number of new feathers without shedding any of the old 

 ones ; by the wearing off^ of the lengthened lighter-coloured tips of the 

 barbs of the feathers on the body, by which the brighter tints of the plumage 

 underneath are exposed ; by an entire or partial moulting, at which old 

 feathers are thrown ofi^ and new ones produced in their places. The first 



