CHAPTER V. 



RECENT EMIGRATION. 



Increase, the Tluling Impulse of Life — The Ice Age and Emigration 

 — Emigration still in Progress — Eftects of Civilization on the 

 Emigration of Birds — Present Emigration in the British Area 

 — Emigration of the Missel Thrush — Eftects of Severe Winter 

 on that Bird — Emigration of Song Thrush and Blackbird — Of 

 the Redstart — Of the Robin, the Nightingale, the Whitethroat, 

 the Willow Wren, and the Wood Wren — Absence of Wood 

 Wren from Norway — Probable Winter Quarters of Individuals 

 Breeding in Sweden — Emigration of Marsh and Sedge Warb- 

 lers—Of the Goldcrest — Migration Waves of Goldcrests — 

 Emigration of Hedge Accentor, Nuthatch, and Tree Pipit — 

 Of the Greenfinch — Fluctuating Breeding Range of this Species 

 in the British Area — Emigration of Sparrows — Emigration of 

 Tree Sparrow to the Faroes — Emigration of Chaffinch and 

 Bullfinch — Of the Starling, the Jay, the ]\Iagpie, and the Rook 

 — Of the Tawny Owl, the Ring Dove, and the Stock Dove — 

 Of the Great Crested Grebe and Woodcock — Table of Species 

 Avhose Emigrations are still in Progress — Analysis of Table — 

 Northward Tendency of Emigration — Emigration attended by 

 Migration — Extinction of British Species — Eftects of Law of 

 Dispersal. 



TllROUC.HOUT the preceding chapters we have en- 

 deavoured to show upon what a vast scale the emi- 

 gration of birds took place, from the close of the Glacial 

 Epoch down to comparatively recent time. We have 

 seen that birds have spread in endless directions from 

 certain centres, emigrated north, east, and west, in which- 

 ever direction an outlet for their increasing numbers 

 was presented, or in which an amelioration of climate. 



