CHAPTER VI. 



INTERNAL MIGRATIONS AND LOCAL MOVEMENTS. 



Vertical Migration — Instances of, in India — Instances of, in 

 Algeria — Not Confined to Endemic Species — Instances 

 among Migratory and Sedentary Species — Vertical Migra- 

 tion among Mountain Species — Similarity between Vertical 

 and Latitudinal Migration — Initiating Causes — Migration in 

 the Southern Hemisphere — Scarcity of Southern Hemisphere 

 Migrants to Northern Hemisphere — Important bearing on 

 Migration of this Fact — Polar Breeding-Grounds — Law of 

 Northern and Southern Migrations — Reversal of Polar 

 Breeding Areas — Results on Migration — Comparative Ex- 

 amination of Northern and Southern Hemisphere Migration 

 — Instances of Northern Migration from Southern Latitudes 

 — Migrationsof Various Petrels — Single Breedingof Migrants 

 — Possible undiscovered Antarctic Breeding-Grounds — 

 Migrants not Breeding in Northern Hemisphere — Neutral 

 Zones of Non-breeding Birds — Isolation of Northern Types 

 in Southern Hemisphere — Local Movements of Birds — 

 Winter Migration — Importance of Local Movements in 

 preserving Species. 



In addition to the prolonged migrations that many 

 birds undertake, there is an immense amount of 

 Internal Migration and Local Movement in progress 

 amongst others at certain seasons of the year. Some 

 of these internal migrations are as regular as the 

 more extended flights, follow certain routes, take 

 place at appointed times. Indeed, so universal are 

 the causes leading to migratory movement of some 



