CHAPTER VII 



Migration An anciently observed phenomenon still imperfectly 

 understood Reasons for it Methods as far as is known 

 Difference between migratory species and the homing Pigeon 

 Widespread tendency to migration, contrasted with con- 

 tradictory tendency to form localized non-migratory races, 

 ending in some cases in Sightlessness, as in some birds of 

 remote islands 



MIGRATION has always been a conspicuous pheno- 

 menon in the lives of certain birds, and often, as in 

 the case of Wildfowl and Quails, intimately bound 

 up with the question of human food-supplies, so> 

 that it is a very familiar fact ; but in spite of this; 

 familiarity, it is still far from being properly under- 

 stood. The old idea of the hibernation of some 

 birds is indeed definitely done away with, and 

 nowadays no one seems to believe that small birds* 

 ever ride on big ones ; yet Bee-eaters in Africa 1 , 

 have been found riding on Storks or Bustards when, 

 these were searching for prey on the ground, and 

 taking their share of the insects driven up ; so- 

 where is the difficulty of a weary Wren or Warbler 

 taking refuge on a Swan or Gannet, which certainly 

 could not dislodge it in mid-air ? I mention this 

 because there is no physical impossibility involved, 



206 



