How Animals Talk 



peatedly on the Nantucket moors, many years 

 ago. The only way I can explain the instantaneous 

 change of flight is by the assumption, no longer 

 strange or untested, that from some alarmed 

 plover on the fringe or at the center of the flock 

 a warning impulse is sent out, and the birds all 

 feel and obey it as one bird. That the warning 

 is a silent one I am convinced, for it seems im- 

 possible that any peculiar whistle could be heard 

 or understood in that wild clamor of whistling. 

 Nor is it a satisfactory hypothesis that one bird 

 sees the danger or suspects the quality of the de- 

 coys, and all the others copy his swift flight; for 

 in that case there must be succession or delay or 

 straggling in the turning, and the impression left 

 on the eye is not of succession, but of almost 

 perfect unity of movement. 



The only other explanation of the plovers' action 

 is the one commonly found in the bird-books, to 

 which I have already briefly referred, and which 

 we must now examine more narrowly. It assumes 

 that all the birds of a migrating flock are moved 

 not by individual wills, but by a collective impulse 

 or instinct, which affects them all alike at the same 

 instant. In support of this favorite theory we 

 are told to consider the bees, which are said to 

 have no individual motives, and no need for them, 

 since they blindly follow a swarm or hive instinct 



[n81 



