216 WARFARE BETWEEN DIFFERENT SPECIES 



then give the reasons which lead me to believe 

 that the fighting not only bears some relation 

 to the "territory," but that it is an important 

 factor in contributing to the attainment of that 

 which for biological interpretation is the end 

 for which the whole territorial system has been 

 evolved. 



Those who have studied wild life on one of 

 the rocky headlands, which are so numerous 

 round our coasts, will probably be familiar with 

 the rivalry that exists between the Raven and 

 certain birds of prey. Where the Raven finds 

 shelter for its nest, there, too, the Peregrine 

 has its eyrie — and so it happens that these two 

 species are continually at war. Now the war- 

 fare occurs not only during the season of 

 reproduction but continues throughout the 

 greater part of the year, and can even be 

 observed in the late summer or early autumn — 

 the period when we should expect to find the 

 instinct least susceptible to appropriate stimula- 

 tion. But it is of a more determined kind 

 early in the spring, and it is then that we often 

 witness those remarkable exhibitions of flight, 

 the skill of which excites our admiration. The 

 Falcon rises above the Raven, stoops at it, and 

 when it seems no longer possible for a collision 

 to be avoided, or, one would imagine, for the 

 Raven to escape destruction, the Raven skilfully 

 turns upon its back and momentarily faces its 

 opponent, and the Falcon with equal skill 

 changes its course, passing upwards and away. 

 The attack, however, is soon repeated, and 



