PASSERINE BIRDS OF NEW YORK 129 



and the adults may sometimes be observed slipping away at the 

 first alarm. Their timidity is probably increased by the somewhat 

 disabled state in which they find themselves owing to the moult. 

 While the feather loss at this time is so carefi.dly compensated 

 for by feather gain that birds as a rule are very little crippled in 

 their locomotive powers, still we may well suppose they feel 

 some anxiety as to their ability to escape when their feathers are 

 only partly developed or new and untried. We must also take 

 into consideration the endeavor manifested by birds to lead their 

 young out of danger, a trait which may influence them to a 

 greater or less extent after the young are quite able to shift for 

 themselves. In flocks of migrants, too, it seems to be the old 

 birds that first take alarm and the loiterers almost invariably 

 prove to be the young birds that have not learned the dangers 

 of delay. The early banding together and departure south of 

 the adults of a particular species that has reared young in a 

 locality near the northern limit of that species may account in 

 great measure for the apparent rarity of local adults because 

 few of us care to brave the midsummer sun, in pursuit of them, 

 but it does not explain "'hy among the hords of migrants from 

 more northern breeding regions so few adults are secured. The 

 theory of a migration of adults by a different route from that 

 taken by the young birds may explain some cases and the rela- 

 tively greater number of young due to the natural increase of 

 species will account for a part of the existing disproportion but 

 none of these explanations is adequate. It is a subject where 

 field work and closet study go hand in hand and it remains to 

 be proved whether my theory of personal safety, the only one 

 I advance in these pages, will be displaced by a better. 



In collections the proportion of young birds taken in the 

 spring when it is possible to determine their age is far smaller 

 than in the fall. In fact adults and young seem to be about 

 evenly divided in numbers, except in the case of bright colored 

 species where the brilliant adults have evidently attracted the 

 collector's attention more than the duller young birds. 



Ann.'XLS X. V. Acad. Scl, XIII, Aug. 4, 1900 — 9. 



