24 COLOURS -OF THE FEATHERS OF BIRDS. 



Thus far Mr. Selby ; but it does not appear to me that this excellent 

 naturalist has made sufficient allowance for the effects produced by 

 the action of the air, and by the nature and quality of the food. He 

 seems to think that the change which takes place at the pairing sea- 

 son, is of itself sufficient to produce, not only the high degree of spirit 

 and pugnacious disposition frequently evinced, and the superior song 

 generally called forth at this period of the year, but also to be the sole 

 cause of this superior brightness of plumage. From this, however, I 

 beg leave, with all deference, to dissent, as I can adduce in sup- 

 port of my opinion, a very familiar example. The common linnet, 

 already mentioned as a very striking instance of the great change 

 of colour, which the same individual feathers undergo at a particular 

 season of the year, is well known never to acquire in the cage that 

 bright scarlet plumage of the breast and forehead, which distinguishes 

 the bird in a state of nature. The male whitethroat also, that has 

 passed the winter in confinement, does not assume the fine rosy tint 

 on the breast, that adorns this species in its wild state! But that birds 

 in confinement feel the genial influence of spring, in common with 

 their brethren in the field, is evident, not only from their superior 

 song at this season, and their quarrelsome and jealous spirit, but from 

 their being frequently known to build a nest, and to produce and rear 

 their young in captivity. 



It necessarily follows, therefore, that the action of the air, the influ- 

 ence of particular food, and perhaps also, of other unknown agents, 

 assist materially in producing this change of colour. 



That certain food may have an influence is probable, from the 

 known effects of particular food upon the plumage of birds in confine- 

 ment ; thus a bull-finch, fed entirely on hemp-seed, will in the course 

 of time become black, not by moulting, but by an actual change of 

 colour in the same feathers ; and if this food only be given to it for a 

 month or six weeks, previous to its change of plumage in the Autumn, 

 the new feathers will appear of that colour. I have seen a goldfinch 

 also, that has been rendered black by the same food, though in this 

 instance, the yellow part of the wings remained unchanged. 



Constant exposure to the fresh air, also, has an effect on the plumage 

 of birds; as the breast of a caged linnet that is kept much out of doors, 

 may be observed to be of a brighter red than that of a bird of the same 

 species, constantly confined in a close room. 



From the above facts it would appear, that the great change of co- 

 lour, which some species undergo at particular seasons, is produced, 

 not so much by any single cause, as by a combination of various and 



