CH. XXVIII. VIGILANCE OF WILD FOWL. 141 



flocks, leave sentries, on whose vigilance the rest 

 entirely depend, taking no heed of anything around 

 them, but feeding in conscious safety. Nor is it 

 necessary for a cry of alarm to be given, as the flock 

 perfectly understand what is going on by the actions 

 or looks of the one who is watching, distinguishing 

 at once whether the sentry is intent on some sound 

 or object at a distance, or whether the danger is 

 imminent and pressing. It is not only by the voice 

 and action of birds of their own kind that flocks of 

 wild fowl guide their actions : the startled move- 

 ment or cry of a redshank or peewit is sufficient to 

 put on wing a whole flock of geese or ducks instant- 

 aneously, and also to tell exactly from what point 

 the danger is to be apprehended. 



