THE AUK : 



A QUARTERLY JOURNAL OF 

 ORNITHOLOGY. 



Vol. xxiii. July, 1906. No. 3. 



SOME LIGHT ON NIGHT MIGRATION. 



BY WITMER STONE. 



Ornithologists have long been familiar with the phenomenon 

 of night migration; that is to say, we recognize that such flights 

 occur on every favorable night during the period of the spring and 

 fall movements; but it is only the accomplished fact that we are 

 actually able to see — the great host of transient birds that are in 

 our woodland in the morning that were not there the previous day. 



The nearest that we can usually come to observing the flight 

 itself is to stand out in the open on some starlit night and listen to 

 the faint chirps that come floating down from the great vault above. 

 We strain our eyes in an effort to catch a glimpse of the throng that 

 we know must be passing overhead, but all in vain, for the migrants 

 of the night are shielded by the darkness alike from friend and foe. 

 To a favored few the opportunity is now and then offered of getting 

 a glimpse of the passing birds. From the top of some lighthouse 

 we may see a few of the transients as they come for a moment within 

 the glare of the lamp and, bewildered, dash themselves against it 

 or pass on again on their course. Sometimes, too, upon the ap- 

 proach of a sudden storm part of the migrants, bewildered and 

 temporarily lost, fly directly against a lighted building or into the 

 illuminated streets of a town or aboard some vessel at sea. Or, 

 again, those who have access to a large telescope may, by keeping 

 it focused " upon the full moon as it rises, see a few of the passing 

 migrants as dark specks silhouetted against the bright disk. 



