How Animals Talk 



flight in harrow-shaped formation; but I have 

 never witnessed anything like a wing drill among 

 them save on one occasion, when a thousand or 

 more of the birds were gathered together for a 

 few days of frolic before beginning the southern 

 migration. Nor have I ever seen the drill among 

 thrushes or warblers or sparrows or terns or sea- 

 gulls, which sometimes gather in uncounted num- 

 bers, but which do not, apparently, have the same 

 motive that leads crows or starlings to unite in a 

 kind of rhythmic air-dance on periodic occasions. 

 A second marked characteristic of the wing drill 

 is that it is invariably a manifestation of play or 

 sport, and that the individual birds, though they 

 keep the order of the play marvelously well, show 

 in their looks and voices a suppressed emotional 

 excitement. The drill is never seen when birds 

 are migrating or feeding or fleeing from danger, 

 though thousands of them may be together at such 

 a time, but only when they assemble in a spirit of 

 fun or exercise, and their bodily needs are satisfied, 

 and the weather or the barometer is just right, 

 and no enemy is near to trouble them. Whatever 

 their motive or impulse, therefore, it is certainly 

 not universal or even widespread among the birds, 

 since most of them do not practise the drill; 

 nor is it in the least like that mysterious impulse 

 which suddenly sets all the squirrels of a region in 



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