12-1: DWIGHT 



a feather which regularly develops, dies and is cast off, can pos- 

 sibly violate such a universal law is not only contrary to com- 

 mon sense but contrary as well to every established fact regard- 



ing the moulting of birds. 



VI. OUTDOOR STUDY OF MOULT 

 Seasons of Moult 



This is a pleasant and fascinating side of the subject of moult 

 for it takes us out into the open air of woods and fields. 

 Hot, muggy August has been considered, the month of moult 

 in the vicinity of New York city, and it will surprise some of us 

 to learn that many of our local species quite complete their winter 

 plumage before August arrives, while others do not begin to 

 assume it until the month has long passed. Although this 

 month does mark the high tide of moult, especially among 

 the adults of a great many species, there are few months in the 

 year when one species or another does not show evidences of 

 feather loss just past or just beginning. A complete moult is 

 accomplished in from four to six weeks, stray feathers continu- 

 ing to appear for a much longer period, but partial moults re- 

 quire much less time. The young of most of our Passerine 

 species remain in the nest about two weeks, a little more or 

 less according to size, this period corresponding very nearly to 

 the duration of the natal down. 



The growth of the juvenal plumage begins while the young 

 bird is still in the nest, the wings and tail requiring several 

 weeks to reach maturity. Birds hardly able to fly will be found 

 which already show signs on the breast of the first winter 

 plumage ; these species as a rule do not lose the wings and 

 tail at the postjuvenal moult ; others however do, and usually 

 such birds will have worn the juvenal plumage for many weeks 

 before the postjuvenal moult begins. 



The blending together of the moults of the young bird makes 

 it difficult to assign the time required for any one of them and 

 the time varies with each species. It can be said, however, that 



