THE LIFE-HISTORY OF BIRDS 281 



year, the quills being shed and renewed in pairs. This method 

 of renewing the quills is best illustrated perhaps by the birds of 

 prey. Owing to the need of preserving absolutely unimpaired 

 the full powers of flight, the work of renewing worn-out feathers 

 is spread over a long period, almost the whole year, in fact. 

 In Pigeons the renewal of the quills appears to take about six 

 months. " About roth May," says Headley, " the tenth of the 

 eleven primaries counting from the outermost is lost. A month 

 later the ninth goes. By that time the tenth has grown nearly 

 to its full size ; when the ninth is about half its proper length 

 the eighth falls; the others follow at intervals of from eight 

 to fifteen days." The tail feathers being of considerable import- 

 ance are similarly moulted in pairs. The first to go are those 

 on either side of the central pair of the twelve which make up 

 the complete tail series. When the new feathers are about three- 

 quarters grown the central pair are shed ; then follow the third 

 pair, counting from the centre outwards, next the fourth, then 

 the sixth or outermost pair, and lastly the fifth pair. As to the 

 order of the coming of the rest of the plumage nothing seems 

 to be known ! The order of the ecdysis of the " quills " among 

 Passerine birds has been very little studied. In the Australian 

 Piping Crow {Gymnorhina tibiceri) this matter was made the 

 subject of an elaborate monograph, wherein it was shown that 

 the quills are moulted in pairs, and in a very definite order, 

 the primary quills moulting from the wrist outwards and the 

 secondaries from the wrist inwards. 



But as to the moulting of Passerine birds generally, ridicu- 

 lously little is known, and for most of our knowledge of this 

 subject we are indebted to the labours of an American Orni- 

 thologist — Dr. Dwight. Of the vast number of species in- 

 cluded in this group observations have been recorded on a 

 few small groups only. Thus, among the Warblers the Black- 

 cap {Sylvia atricapilla) is said to moult but once annually, 

 while the Garden Warbler (5. salicarid) and the White-throats 

 {S. rufa and S. curruca) are commonly believed to moult twice. 

 The Buntings (Embefizidm) again seem to show similar differ- 

 ences, some species changing their raiment once, some twice, 

 annually. If this is true it will be interesting to see whether, 

 for instance, a dull-coloured species, like the Corn Bunting, 

 belongs to the first, and the Yellow-ammer {E. citrinelld) to 



