CONDITION ACCOMPANYING CHANGE 237 



one of the adversaries, and in which consequently 

 the fighting seldom reached any high degree of 

 severity. We must now consider some others 

 in which each of the opponents acts as a 

 stimulus to the pugnacious instinct of the other. 

 It is here, of course, that we find the most 

 violently contested battles, and it is here, too, 

 that the purpose of the fighting seems clear. 

 The persecution which the Green Woodpecker 

 suffers from the Starling is well known. The 

 purpose of the Starling's behaviour is clear, 

 namely the possession of the hole occupied 

 by the Woodpecker. Bird for bird, the Wood- 

 pecker is more than the equal of the Starling, 

 but persistent endeavour ultimately wins the 

 day. The Starlings perch close beside the hole, 

 and, whenever the Woodpecker shows itself, 

 attack with determination ; and not only do 

 they do so but they are assisted, so there is 

 reason to believe, by other individuals or pairs 

 in the attainment of their end, so that no matter 

 how stoutly the Woodpecker defends itself, in 

 time it is almost certain to be deprived of its 

 ownership. 



In like manner different kinds of Wood- 

 peckers contend with one another for the 

 possession of a hole, and here the opponents 

 are more equally matched. I have seen a pair 

 of Lesser Spotted Woodpeckers endeavouring 

 to drive away a Great Spotted Woodpecker. 

 The excitement of all three birds was exceptional. 

 Each of the Lesser Spotted Woodpeckers kept 

 swooping in turn at their rival, sometimes in the 



