50 MIGEATION. 



accompanying them on their annual journeys up the valley of the Petchora, and down that 

 of the Kama into the valley of the Volga, and thence by way of the Eed Sea or the Nile to 

 South Africa, the natural winter-quarters of birds breeding in Arctic Europe, they retrace 

 the steps of their gradual emigration across half a dozen Arctic valleys, to follow their old 

 fly-line down the Pacific coast of Asia. 



There are many other facts connected with emigration and migration that are of great 

 interest, but which would require a large volume to do them justice. The assemblage 

 of migratory birds in large flocks, which in many cases wait for a favourable wind 

 (they prefer a beam-wind) before they venture to cross wide stretches of sea, and conse- 

 quently start all together as soon as the weather is suitable, and arrive on the other 

 coast in enormous numbers or " rushes " ; the keen sight of birds and their extraordinary 

 memory for locality; the great variety of routes chosen, and the pertinacity with 

 which each species keeps to its own route — these and many other facts all point in 

 one direction. The desire to migrate is a hereditary impulse, to which the descendants of 

 migratory birds are subject in spring and autumn, which has during the lapse of ages 

 acquired a force almost, if not quite, as irresistible as the hereditary impulse to breed in 

 the spring. On the other hand, the routes of migration have to be learned by individual 

 experience. The theory that the knowledge of when and where to migrate is a mysterious 

 gift of nature, the miraculous quality of which is attempted to be concealed under the 

 So-called semi-scientific term of instinct, is no longer tenable. Birds may not have such highly 

 developed reasoning-powers as we have, but their memories and power of perception must 

 exceed those of the cleverest Zulu, probably as much as the almost miraculous development 

 of these qualities in the African exceeds the coarse and blunted faculties of the European. 



The conclusion to which all these interesting facts point is that emigration has played 

 a most important part in the distribution of birds, and that in many cases the present 

 routes of migratory birds furnish a key to the direction which it must have taken in ages so 

 remote that we can scarcely realize the lapse of time since it occurred. 



" Instinct.' 



