in *which Changes of Colour are effected in Moulting. 301 



Now, a knowledge of the fact just stated, of a seeming refer- 

 ence in the changes of one group to those of others, to which 

 it is related by the tie of physiological affinity, might induce 

 the inference that, as some groups moult twice in the year, 

 and others in autumn only, it would follow that single-moulting 

 birds, which had not been able to complete their change at 

 the proper season, would do so at the time of the vernal reno- 

 vation of the others, did not observation fail to confirm this 

 highly reasonable supposition, as in the case mentioned of the 

 snowfleck. It is true that some species are, in confinement, 

 subject to an unhealthy loss of feather in the winter months, 

 which, early in spring, exhibit a sudden restoration of clothing, 

 that might be mistaken for a moult ; but this is connected with 

 the general invigoration of the whole system, which always 

 then takes place, coincidently with an internal developement, 

 and is unaccompanied by any casting of the plumage. 



Here, it may be mentioned, by the way, that I am not quite 

 certain that all single-moulting birds change their plumage in 

 autumn, having met with one fact, at least, which renders this 

 somewhat doubtful. A fine healthy-looking specimen of the 

 black-throated loon, in thoroughly mature plumage, obtained, 

 in one of the markets, early in January, had obviously not 

 changed its feathers the preceding autumn : the purple gloss 

 upon its throat had almost disappeared ; and the black termi- 

 nations to its white-spotted scapularies had come off, leaving 

 the white terminal, as observed in the seasonal shedding of 

 the deciducus tips to the feathers so prevalent among the 

 smaller Insessores; in a word, the whole plumage bore every 

 indication of a twelvemonth's wear; and there appeared suf- 

 ficient reason at least to suspect that it would have been 

 renewed in spring, as always happens with the younger birds 

 of this genus ; though whether the same constantly obtains 

 with the adults, I have not, at present, the experience to 

 decide. Should it prove so, this would be a singular negation 

 to an otherwise universal rule, so far as I have hitherto been 

 able to investigate. 



It is now several years since I happened to notice, while 

 sojourning at the house of a friend, that a young jackdaw that 

 was running about his garden moulted its nestling primaries; 

 while a variety of young thrushes, also in his possession, re- 

 tained the quill and tail feathers while shedding their clothing 

 plumage. To illustrate this familiarly, it may be presumed 

 that many persons have noticed, that a young jackdaw or 

 magpie, that had had its wing clipped as soon as it could fly, 

 regained the use of its wings at the first moulting season ; 

 whereas a young caged blackbird, that had injured its wings 



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