CONTENTS. 



VKGfl 



parative Avifaunas — Reasons for Poorness of Nearctic 

 Avifauna — Winter Quarters of Pal?earctic Migrants — 

 Winter Zones of West Pal?earctic Birds — Winter 

 Zones of East Palsearctic Birds — Comparison of 

 Winter Range of East and West Palaearctic Species — 

 Influence of Gulf Stream on Geographical Distribution 

 and Migration of Birds — Climate of Nearctic Region — 

 Effects on Migration — Winter Zones of Nearctic Mi- 

 grants — Bird Life in the Southern Zones during 

 Winter — Winter Quarters of Southern Hemisphere 

 Migrants — Northern Sea Flights — Isothermal Lines 

 of Temperature — Temperature and Breeding-Grounds 

 — Effects of varying Temperature on Birds — Our 

 Knowledge of the Geographical Distribution of Birds 

 yet rudimentary ... ... ... ... ... 187 



CHAPTER X. 



THE SPRING MIGRATION OF BIRDS. 



The Dominating Impulse of Spring Migration— General 

 Aspects of Spring Migration — The Greatest Travellers 

 generally the Latest Starters— Avian Waves of Spring 

 Migrants— Spring Routes sometimes different from 

 Autumn Routes — Intensity of Migration — Spring 

 Migration of Turtle Dove and Common Sandpiper — 

 Day and Night Migration reversed according to 

 Season — Minor Streams of Spring Migrants — 

 Abnormal direction of Fly-lines — IMigration of Rose- 

 coloured Pastor, Scarlet Rose Finch, and Black- 

 Headed Bunting — Spring Migration gradual in 

 Southern Zones — Sudden Spring Migration in Arctic 

 Regions — Arrival of Birds in Northern Europe — 

 Arrival of Birds in Siberia — Rush of Birds across the 

 Arctic Circle — Migration of Geese— Arrival of Waders 

 — Various Routes to the Tundra from the South — 



