BIRDS IN AUTHORITY 51 



bird of masterful temper making himself head and 

 tyrant of his fellows, albeit it is less common or less 

 noticeable among birds that have the social habit 

 than it is among mammals. It appears to me that 

 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 helpful 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 fe- 

 males 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 



