148 BIRD LIFE GLIMPSES 



gradually, as one watches — especially if one comes 

 night after night — the reason begins to appear. For 

 a long time the current of flight flows on, unin- 

 terruptedly, hiding with its mantle whatever of form 

 or substance may lie beneath. But, at last, the 

 numbers begin to wane, the speed — at least in ap- 

 pearance — to flag, and it is then seen that the star- 

 lings are flying in bands, of comparatively moderate 

 size, which follow one another at longer or shorter 

 intervals. Sometimes there is a clear gap between 

 band and band, sometimes the leaders of the one are 

 but barely separated from the laggards of the other, 

 sometimes they overlap, but, even here, the band 

 formation is plain and unmistakable. This, as I 

 have said, is towards the end of the flight. On 

 most occasions, nothing of the sort is to be seen at 

 its beginning. There is a sudden outrush, and no 

 division in the continuous line is perceptible. Occa- 

 sionally, however, the exodus begins in much the 

 same way as it ends, one troop of birds following 

 another, until soon there ceases to be any interval 

 between them. But though the governing principle 

 is now masked to the eye, one may suppose that it 

 still exists, and that as there are unseen currents in 

 the ocean, so this great and, apparently, uniform 

 stream of birds, is made up of innumerable small 

 bands or regiments, which, though distinct, and 

 capable, at any moment, of acting independently, are 

 so mingled together that they present the appear- 

 ance of an indiscriminate host, moving without 

 order, and constructed upon no more complex prin- 

 ciple of subdivision than that of the individual unit. 

 There is another phenomenon, to be observed in 



