308 Reconciliation of apparent Discrepancies in the Mode 



the ermine, they undoubtedly seem to be produced by tem- 

 perature only, I think there is much reason to suspect that 

 the double-moulting ptarmigan would become white in winter, 

 even though removed from its frigid habitat. This can only 

 be ascertained by keeping them for some time in confinement, 

 which I am not aware has ever been attempted. 



It is now time, however, that I reverted to the explanation of 

 those appearances in the young mallard, and also the pintail, 

 and some other species, which would lead any unpractised 

 observer to suppose that the excessive change from the fe- 

 minine to the male garb was effected in these birds without a 

 renewal of the feathers. To a certain and very considerable 

 extent, a change of hue unquestionably does take place ; 

 but, without resorting to observation of the domestic breed 

 for assistance in the elucidation of this difficulty, I think that 

 a little attention to the following circumstances will go far to- 

 wards determining that an actual moult had taken place, in 

 which the birds had assumed an intermediate garb, in various 

 degrees removed from the perfect livery, according to the 

 respective vigour of each individual ; the completion of the 

 colours being subsequently induced by a change of tint only 

 in the same feathers. 



Nothing is more usual than to perceive traces of the femi- 

 nine markings in the new feathers which we see growing, in 

 spring, on those Anatidae which are brought to market in a 

 state of moult ; this fact being precisely the reverse of that 

 already noticed, of the tinging of the old feathers with the 

 new colouring matter, which is commonly visible in the same 

 specimens. The younger, therefore, a bird of this tribe might 

 be at the time of undergoing its moult, the greater admixture 

 of these traces of the female colouring we should expect to 

 find upon its new plumage. Supposing the young mallards, 

 therefore, to have completed their moult at the time we see 

 them, there is nothing to excite surprise at the considerable 

 observed intermixture of the female markings. 



But, that a change of feather had certainly taken place, at 

 least in one instance, is conclusively shown by their all pos- 

 sessing the singular curled feathers of the tail, while not the 

 slightest trace of these having been recently renewed is dis- 

 cernible. The same applies to the analogous elongated 

 central tail-feathers of the pintail ; and, in both instances, I 

 have constantly found that these are shorter and smaller- 

 looking than in the older birds. I have mentioned that, in 

 one case (but this out of many hundreds), I have seen a male 

 pintail moulting in spring ; and it is worthy of remark, that, 

 in this bird, the long central tail-feathers were developed to 



