3i6 A HISTORY OF BIRDS 



interest, because it has been already shown that the character- 

 istic colour of the flesh of salmon is due to the red colouring- 

 matter extracted from the Crustacea on which it feeds. Thus, 

 as in the case of cayenne-fed canaries, to which we have already 

 referred (p. 310) pigment is not only reacquired by each 

 individual, but may be lost and regained several times in the 

 life-time of the same individual ! 



The European YX-Amva^o {^PJicenicopteriis roseus), it is signifi- 

 cant to note, though feeding on a precisely similar diet, has 

 only the wings, beak and legs vividly coloured, while the rest 

 of the body is merely flushed with rose-pink. The Scarlet and 

 White Ibises of Tropical America afford a precisely similar 

 instance, the former {Eudodnius ruber) having a plumage of 

 a gorgeous scarlet colour, which in captive birds fades moult 

 by moult to white, and the latter, Eudocinius alba, being, as its 

 specific name indicates, pure white, save for the beak and legs, 

 which are red. The brilliantly coloured species then depend 

 for their beauty upon some unstable physiological peculiarity 

 which is not present in the less resplendent species. 



Another remarkable experiment of Mr. Beebe may be 

 mentioned in this connection. This was carried out on some 

 Scarlet Tanagers {Pyranga erythroinelas) and Bob-o-links {Doli- 

 dionyx oryzivorus) under his charge in the New York Zoological 

 Gardens, Both species have very distinct breeding and non- 

 breeding (summer and winter) plumages. The first-named 

 changes annually from scarlet and black to green and black 

 (see p. 275), the last from buff, cream and black, strongly con- 

 trasted, to dull brownish-black and buff. 



Several individuals of both species, when in full breeding 

 plumage, were placed in small cages, and kept in a dimly lighted 

 apartment, but well supplied with food, when, as a consequence 

 they became very fat. A month later, when the time for the 

 annual assumption of the winter dress arrived no change of 

 plumage took place. In the following spring " individual 

 Tanagers and Bob-o-links were gradually brought under normal 

 conditions and activities with quick result ; just as the wild birds 

 in their winter haunts in South America were at that time 

 shedding their winter garb, and assuming the more brilliant 

 hues of summer, so the birds under my observation also moulted 

 into the colours appropriate to the season. The old scarlet 



