266 RELATION OF TERRITORY TO MIGRATION 



of external constraint but because it derives 

 some pleasure from satisfying something in its 

 organic complex. We speak of this behaviour 

 and of the emotion which characterises it as the 

 gregarious instinct : by which we mean that the 

 inherited nature of the Curlew, as a tribe, is so 

 constituted that, given the appropriate internal 

 conditions and adequate external stimulation, 

 every individual will respond in a similar manner 

 that is, the behaviour is primarily determined 

 by racial preparation. This is what we mean 

 by the gregarious instinct biologically considered. 

 We may resolve our own experience in relation 

 to the crowd into its simplest constituents, 

 project our own primitive feelings into the 

 Curlew, and say that the bird feels uneasiness 

 in isolation and satisfaction in being one of the 

 flock. But in truth we know nothing, save by 

 analogy, of the correlated psychical state. All 

 the knowledge we possess is derived from a 

 study of the objective aspect of the behaviour, 

 which in simple terms may be expressed thus : 

 the individual is drawn towards its companions ; 

 there is a relation between the size of the flock 

 and the strength of the attraction ; and all 

 Curlew behave similarly under similar circum- 

 stances. 



This instinct controls the movements of 

 many birds from early autumn to the com- 

 mencement of the breeding season. And so 

 powerful is the control that the individual is 

 suppressed and its activities subordinated to the 

 welfare of the community as a whole. Flocks 



