CHAPTER III. 



THE PHILOSOPHY OF MIGRATION. 



Wings of Migratory Birds — Plumage of Migratory Birds — 

 Moulting — Order of Migration in Autumn — Avant-Coiiricres 

 — Migration of Young Birds before Parents — Order of 

 Migration of Adults — Order of Migration in Spring — Time 

 of Migration Flight — Punctuality of Migrants — Amount of 

 Sociability and Gregariousness in Migrants — Weather-bound 

 Migrants — Duration and Progress of Migration — Speed of 

 Migration Flight — Rapid Flight of Dotterel in Spring — 

 Altitude of Migration Flight — Influence of Bright Lights 

 on Migrating Birds — Migrants at Lighthouses and Light- 

 ships — Effects of Reflected Light — Advantages derived 

 from Lofty Flight — Possible Use of the Balloon in studying 

 Migration — Cries of Birds on Passage — Effects of Wind on 

 Migration — Influence of Temperature on Migrating Birds. 



The two preceding chapters have been primarily 

 devoted to the biography, antiquity, and origin of 

 migration ; it now becomes necessary to deal with 

 the actual phenomenon itself. We have seen when 

 and how migration had its origin, now let us trace 

 the various conditions under which it is practised. 

 Fhghts of such enormous magnitude are not lightly 

 undertaken, and many things have to be considered 

 during their progress. Even before they are com- 

 menced certain preparations have to be made, and 

 many, and varied, and complex are the influences 

 inseparably associated with these wonderful journeys. 



