CONTENTS X 



I'AGE 



ous Routes of Migrants to West Africa — British Summer 

 Migrants from the South-East — British or West European 

 Species that have Emigrated from South-Eastern Areas — 

 Their Absence from Iberia — Their Allied Forms and Re- 

 presentative Species — Influence of Competing Species — 

 Reasons for their Absence from British Area — Abnormal 

 Migrants to British Area — West European Species nor- 

 mally Absent from British Area — Reasons for such Absence 

 — Past Emigrations of Storks and Red-crested Pochard — 

 Emigrations of Blue-headed Wagtail and Allies — Situation 

 of British Area now unfavourable to Emigration — Instances 

 showing Impassable Nature of a Sea Barrier — Avian Emi- 

 gration to Greenland — Nearctic Emigration — Post-Glacial 

 Emigration of Birds in West Europe — Emigration to Ice- 

 land and Greenland across the British Area — Table of 

 Emigrants ... ... ... ... ... ... ... 59 



CHAPTER IV. 



THE GL.\CIAL RANGE CONTRACTION AND POST-GLACIAL 

 EMIGRATION OF BRITISH BIRDS {continued). 



Anomalous Facts — Analysis of the Facts suggested by pre- 

 ceding Table — Table demonstrating the two Dominant 

 Lines of Post-Glacial Emigration in the extreme West of 

 Europe — Analysis of Table — \'ariations in the Northern 

 Limits of Species — Ancient Line of Emigration from the 

 British Area Eastwards into Continental Europe — The 

 North Sea Plains — Their Gradual Submergence and its 

 Effect on Birds — Table of East and North-East Emigrants 

 — Analysis of Table — Influence of Temperature on Birds — 

 Effects on Birds of Isolation of British Area from Con- 

 tinental Land — Professor Geikie on Emigration to the 

 British Area — Emigration to Ireland — Impossibility of 

 Southern Emigration to this Area from Scotland — Migra- 

 tion of Birds in the Valley of the Petchora — Emigration 

 of Birds within the British Archipelago — Resident Species 

 — Table of Resident Species — Analysis of Table — Absence 

 of Birds from Ireland— Summer Migrants — Table of 

 Summer Migrants — Analysis of Table — Table of Autumn 

 Migrants to and Coasting Migrants over the British Islands 

 — Analysis of Table — Table showing the Proportional Dis- 

 tribution of Species over the British Area — Deductions 



