COLOUR IN BIRDS AND QUADRUPEDS. 217 



former day two or three individuals were brought to me in which 

 moulting had commenced. From this period until every straggler ap- 

 peared to have left us, on the 23d, I discovered that the process of 

 moulting was advancing rapidly. It seemed to commence in the old 

 males, extending itself to the females; and on my last examination not 

 an individual of either sex w^as brought to me that w^as not in extensive 

 moult. The young feathers on the head came out black ; those on the 

 rest of the body of a bright yellow. In the old feathers no change 

 whatever had taken place. Mr Ord is correct when he states that this 

 species is in full song in March ; this was the case in all the individuals 

 I observed ; but he appears to have overlooked the opportunity of ascer- 

 taining that it was also in full moult. The theory that the song of 

 birds is silenced in consequence of the exhausting process of moulting, 

 is not calculated to bear the test of close examination. The Fringilla 

 tristis, Troglodytes sedon, Fringilla Pensylvanica, F. graminea, Syl- 

 via pensilis, and many others, were in full song, although they were 

 moulting very extensively. This is also the case at the moment I am 

 writing, in several species now in my aviary. It will probably be found 

 that the vocal powers of birds are called forth by an increased develop- 

 ment of the sexual organs, in the vivifying season of spring, and that 

 their song is suspended in autumn, when these organs are sensibly di- 

 minished. 



Psittacus leucocephalus, White Fronted Parrot. A bird of this spe- 

 cies, now in the possession of my friend Dr Wilson of this city, was 

 carefully examined on the 20th of March. It was in fine health, re- 

 peated several words, and made attempts at a song. We found it in 

 extensive moult, and all who examined it were satisfied that it was 

 receiving a full set of new feathers on every part of the body. This 

 species exhibits a variety of colours, green, white, yellow, pink and red. 

 The feathers came out apparently in the bright hues which the bird 

 assumes when in perfect plumage. In pursuing my investigations on 

 the change of plumage in birds, I have observed that old birds, moult- 

 ing in spring, usually receive their bright colour at once, v»^hilst many 

 species, that moult in autumn, have these colours imparted to them by 

 a gradual process. 



Psittacus coccinocephaliis, Scarlet Headed Parrot ; Psittacus purpii- 



