ii8 HOW TO STUDY BIRDS 



circumstances, birds will seem very scarce. But let 

 it turn cool, and the migratory wave starts along. 



The abundance of migrants at any date varies 

 greatly from year to year. My notes record that one 

 September birds were scarce up to the middle, and 

 then a perfect flood of migration set in. On the 

 seventeenth I wrote down that the numbers of black- 

 poll warblers in the woods were almost beyond be- 

 lief, and many other birds were found in profusion. 

 But a year later at the same date birds were very 

 scarce, and through September it was hard to find a 

 blackpoll. Not till the middle of October did I 

 note any large tide of these birds. 



To find birds in the autumn we must depend almost 

 wholly on seeing rather than hearing. Sharp eyes 

 rather than ears now count. The songless warblers 

 hardly seem like the same birds that in spring were 

 constantly breaking forth into joy. The little lisp or 

 chirp which they emit seldom has any distinguishing 

 quality. It simply makes us aware of the presence 

 of a bird, and we must hunt each one to see what it is. 

 We may well be thankful if they make any sound at 

 all. 



The flocking of certain other birds which I have not 

 mentioned Is noticeable in September. That of the 

 nighthawks then reaches Its climax. Some days dur- 

 ing the earlier part of the month they keep passing 

 In straggling bands, but the flight began In August, 

 and by the middle of September nearly all have left 

 us, though a few may be seen later. The chimney 



