CHAPTER XI 



THE AUTUMN MIGRATION" OF BIRDS. 



Impulse of Migration in Autumn — Conditions of Migration 

 in Autumn reversed — Migrations of Cuckoos — Duration 

 of Autumn Migration — Difficulty of Noting the Departure 

 of Birds — Direction of Migration Flight — Gregariousness 

 of Birds in Autumn — Autumn in the Arctic Regions — 

 Migration Correlated with Terrestrial Change — Abundance 

 of Birds in Autumn — Minor Streams of Autumn Migration 

 — The Great East to West Wave of Western Palcearctic 

 Migration — Rare Visitants to Western Europe from the 

 East — Concurrent Streams of Migration flowing in opposite 

 directions along the same Routes — West to East Migration 

 in Nearctic Region — Punctuality of Departure in Autumn — 

 Wandering Mania in Young Birds — Table of Autumn 

 Migrants — Reversal of Migratory Impulses in Old and 



Young. 



The Great Autumn Migration of Birds is just as 

 interesting, although it may not be quite so 

 apparent in its earlier stages, as that taking place 

 in spring. The most important impulse of Autumn 

 Migration is unquestionably the failure of food 

 supply ; that this Impulse is even more deeply 

 rooted than that which prompts migration in 

 spring is apparent in the fact that All migratory 

 birds, young and old alike, bow to its irresistible 

 dictates. So often and so regularly has the grand 



