236 WARFARE BETWEEN DIFFERENT SPECIES 



an individual, when in company with the flock, 

 may be called upon to endure, its customary 

 hostile response will fail to be elicited. An 

 incident which happened in the spring of 1917 

 will serve to make this clear. A flock of some 

 thirty Yellow Buntings, Greenfinches, and 

 Chaflinches were feeding in one corner of a 

 field which had recently been sown with barley. 

 As they sought their food they wandered 

 outwards into the middle of the field, and in 

 so doing, passed across the territory of a Sky- 

 lark. Whereupon the Skylark became excited, 

 uttered its call-note rapidly, and rising a few 

 feet from the ground, attacked those members 

 of the flock that were nearest, which happened 

 to be the Yellow Buntings ; and so determined 

 were its onslaughts that the Yellow Buntings 

 were forced to retire. The Skylark showed no 

 discrimination as to sex, but attacked both males 

 and females, and within a few minutes succeeded 

 in driving away at least two pairs. One would 

 have expected that the Yellow Buntings would 

 have made some show of resistance ; one would 

 have thought that the fact of being violently 

 attacked would have supplied a stimulus 

 sufficiently strong to evoke a corresponding 

 hostile response : yet there was no mistaking 

 the lack of interest that they displayed in the 

 contest— they made no effort to retaliate but 

 seemed to accept the situation as unalterable 

 and left. 



So far we have examined only those cases in 

 which the pugnacious instinct was stimulated in 



