BIRDS IN AUTHORITY 51 



the instances given above are not of this kind. The 

 spirit, the motive, is different. Here the bird is seen 

 to take the mastership for the general good, and 

 we can only suppose that, with or without greater 

 strength and intelligence than his fellows, he un- 

 doubtedly possesses a keener sense of danger, or 

 superior alertness, and a larger measure of that help- 

 ful spirit without which wild animals could not exist 

 in a social state. The action of the gander and of the 

 trumpeter in driving their fellows home in the evening 

 must be regarded as similar in its origin to that of the 

 male swift when he hunts his mate back to the nest 

 and of the sand-martin I observed chasing the 

 females of the colony to their burrows. In a lesser 

 way it may be seen in any flock of birds; they move 

 about in such an orderly manner, springing, as it 

 appears to us, simultaneously into the air, going 

 in a certain direction, settling here or there to feed, 

 presently going away to another distant feeding- 

 ground or alighting to rest or sing on trees and bushes, 

 as to produce the idea of a single mind. But the flock 

 is not a machine; the minds are many; one bird 

 gives the signal — the one who is a little better in his 

 keener senses and quicker intelligence than his com- 

 panions; his slightest sound, his least movement, is 

 heard and seen and understood and is instantly and 

 simultaneously acted upon. So well and quickly is 

 he understood and obeyed that the fact of his leader- 

 ship or promptership is difficult to detect. Another 

 manifestation of this same helpful spirit with which 

 observers of wild animals are familiar, is seen in the 



