498 CLASS AVES. 



*' Independent of the support from analogy which the 

 ermine furnishes, we may observe that the colours of other 

 parts of a bird vary according to the season. This is fre- 

 quently observable in the feet, legs, and bill. Now, since a 

 change takes place in the colouring secretions of these organs, 

 what prevents us from supposing that similar changes take 

 place in the feathers? But, even in the case of birds, we 

 have before us an example as convincing as the ermine already 

 mentioned, — it is a specimen of the little auk {alca alle,) 

 which was shot in Zetland, in the end of February, 1810. 

 The chin is still in its winter dress of white, but the feathers 

 on the lower part of the throat have assumed a dusky hue. 

 Both the shafts and webs have become of a blackish-gray 

 colour at the base and in the centre, while the extremities of 

 both still continue white. The change from black to white is 

 here effected by passing through gray. If we suppose that, 

 in this bird, the changes of the colour of the plumage are 

 accomplished by moulting, or a change of feathers, we must 

 admit the existence of three such moultings in the course of 

 the year : one by which the white winter dress is produced, 

 another for the dusky spring dress, and a third for the black 

 garb of summer. It is surely unnecessary to point out any 

 other examples in support of our opinion on this subject. We 

 have followed nature, and our conclusions appear to be justi- 

 fied by the appearances which we have described." 



This has been the reason why we find some confusion and 

 diversity among naturalists, in classifying the flycatchers of 

 which we speak. In Brisson and BufFon we find them marked 

 under these names, Gobe-mouche JYoir, on de Lorrainet 

 Traquet d' Angleterre, and Bec-figue, as three distinct species. 

 The Black-collared Flycatcher in Latham, Gmelin, and Meyer 

 is a variety of that without collar, and the Becafico a particu- 

 lar race. Other naturalists make but a single species of these 

 three birds, considering the collared flycatcher as a male in 

 very advanced age. M. Vieillot considers that there are two 



