218 WARFARE BETWEEN DIFFERENT SPECIES 



gain possession of the hole which the Wood- 

 pecker with much skill has drilled for itself. 

 As far as my experience goes, the Starling is 

 always the aggressor, and there is only too good 

 reason to fear that, in the course of time, the 

 Green Woodpecker will disappear as a result of 

 the greater fertility and tenacity of its enemy. 

 The Martin suffers a similar kind of persecution 

 from the House- Sparrow, and here again there 

 is reason to believe that the greater virility of 

 the Sparrow will hasten the extinction of its 

 rival. In cases of this description the purpose of 

 the fighting is clear, and one can understand 

 why such divergent species should be hostile to 

 one another ; yet others, equally remote in the 

 scale of nature, are hostile when no such 

 ostensible reason can be assigned for their 

 hostility. Few birds are more pugnacious than 

 the Moor-Hen, and the determined manner 

 in which different individuals fight with one 

 another is notorious. But the intolerance it 

 displays towards other species is no less remark- 

 able, and its pugnacious instinct seems to be 

 peculiarly susceptible to stimulation by different 

 individuals belonging to widely divergent forms. 

 At one moment a Lapwing may be attacked, 

 at another a Thrush or a Starling, harmless 

 strangers that have approached the pool to 

 drink ; even a Water-Rail, as it threads its way 

 through the rushes, may fail to escape detec- 

 tion ; and, which is still more curious, a covey 

 of Partridges will evoke response if they 

 approach the pool too closely. 



