90 DWIGHT 



appear to be only inner secondaries, do not as might be ex- 

 pected, follow their sequence of moult. The middle one falls 

 with or even before the distal secondary, and in spite of some 

 irregularity the three are almost always grown in advance of 

 the inner secondaries. The middle feather is the first to be lost, 

 followed by the innermost, and this in turn by the outermost, 

 which often acquires complete maturity before the adjacent 

 secondary, the sixth, falls out. 



The tertiaries follow in their moult most frequently, per- 

 haps, the example of the adjacent body plumage, but are very 

 irregular, individuals of the same species acting in defiance of 

 what might be expected of them. Some adults regularly renew 

 them at the prenuptial moult when the body plumage is re- 

 newed, but even these birds may replace only one or two 

 feathers and asymmetrically in either wing. Young birds are 

 still more irregular and old feathers frequently persist in one 

 bird and* not in another of the same species, as may be seen in 

 the Rose-breasted Grosbeak (Habia ludoviciand], or Baltimore 

 Oriole (Icterus galbuld) and many others. When young birds 

 acquire plumage of adult structure in the early autumn of their 

 first year, the tertiaries are often replaced by others so similar 

 in color, pattern and structure, that it is very difficult to be sure 

 of their moult, unless they are caught in the act. As they 

 moult quickly, it is not always easy to do this, and as they wear 

 quickly it is easy to mistake their age. Sometimes a precocious 

 young bird acquires one or two of adult color that are not 

 normally due until a later moult. It is doubtful if such feathers, 

 when assumed in the autumn, are again renewed in the spring. 



The moult of the ahilce, the feathers on the ''thumb" of each 

 wing usually follows the example of the wing coverts, most fre- 

 quently being renewed when they are, but often not. The three 

 larger feathers fall with or a little after the proximal primary. The 

 proximal feather falls first, sometimes the middle one, followed 

 by the distal. The smaller feathers which act as coverts are 

 earlier and related in moult to those of the carpo-metacarpal 

 region adjacent. The alulce are quite irregular and are moulted 

 by some individuals of a species and not by others. 



