J3S7-] Correspondence: 260 



ion, is much the more reliable, for reasons which will be given presently. 

 It includes a long array of notes, from which I select and condense the 

 following : — 



"At all points where I have collected regularly and systematically 

 through July, August and September I have found that the adults of most 

 of the smaller land birds which migrate before October, and especially of 

 those which migrate by night, begin to disappear as soon as the young 

 become able to shift for themselves. Their departure is usually gradual, 

 ami often scarcely perceptible from day to day; but before there is any 

 appreciable diminution in the number of young the adults have become 

 so scarce that they commonly represent less than five, and often not more 

 than one per cent, of the total number of individuals of their respective 

 species present. As a rule they disappear as soon as, and often before, 

 they have completed their summer moult, whereas the young usually lin- 

 ger for some time after their autumnal plumage is perfected. Every New 

 England collector who has paid especial attention to obtaining adult birds 

 in full autumnal dress will testify to the truth of this statement. With 

 the Warblers there is often the greatest difficulty in securing such repre- 

 sentatives of even the commonest species. 



" My experience with species which come from further north is that the 

 first flights are composed largely, and often entirely, of old birds. The 

 reason why this fact has been overlooked, or even positively denied by so 

 many observers, becomes apparent when we consider the dates at which 

 even the earlier autumnal migrants are said to reach Massachusetts from 

 the north. 



"Almost without exception the time is fixed somewhere in September, 

 and I venture to say that the majority of the New England collectors 

 still believe that September 1 marks about the beginning of the autumnal 

 migrations. This impression has resulted from the fact that our collectors 

 are usually absent at the mountains or seashore during August. Even if 

 obliged to pass the dog-days nearer home, they rarely think of taking the 

 field at a time when it is supposed that there is nothing of value to be had 

 there. The weather is hot and enervating, the foliage is at its densest, 

 'birds are silent and hard to find, and most of them in such ragged plu- 

 mage that they are worthless as specimens.' 



" Now the simple truth is that the migrations of the most of our small 

 birds begin early in August. During the last two weeks of that month 

 there are usually several real ' rushes,' when the woods throughout Eas- 

 tern Massachusetts are filled with such northern species as Turd us swai'n- 

 soni, Sitta canadensis, Dcndroica coroiiata, D. maculosa, D. blackbumice, 

 D. castanea, Sylvania pusilla, S. canadensis, Seiurus noveboracensis, 

 Empidonax flaviventris, etc." 



It is gratifying to have so much of the above corroborated by Mr. Beck- 

 ham's experience. Perhaps other contributors to 'The Auk' may be able 

 to add something on this interesting and important subject. 



William Brewster. 

 Cambridge, Mass. 



