230 STUDIES IN BIRD-MIGRATION 



General Remarks on Autumn Emigration and Immi- 

 gration. — Having treated of the autumn movements, 

 both of emigration and immigration, it may be desirable 

 before proceeding further to consider their effects on 

 the Skylark population of Britain, and its position at the 

 end of that season. Though vast numbers of home- 

 bred birds have at that time quitted our shores, their 

 departure has not materially affected the great abun- 

 dance of the species, partly owing to the fact that the 

 Skylark is double-brooded,^ and hence its annual increase 

 is enormous, while prodigious numbers have poured into 

 England from Central Europe during part of September 

 and throughout October, to say nothing of the immense 

 number of immigrants from North- Western Europe to 

 the British Isles generally, which have arrived during 

 the latter month. The result is, that from November 

 to the setting in of cold weather, the Skylark population 

 of the British Isles is at its maximum, and vastly in 

 excess of what it is at any other period of the year. 



During these great and varied autumn movements, 

 immense numbers of Skylarks perish at the lanterns of 

 the numerous light-stations both on and off our shores. 

 Indeed, no other bird is so great a martyr to the allure- 

 ments of the beacon light. My experiences of some 

 of these terrible immolations are related on pp. 291 

 and 344. 



Winter Emigration from, and Partial Migration 

 zvitkin, the British Islands. — These movements depend 

 wholly on the state of the weather, and vary in degree 

 according to its severity. The Skylark, obtaining the 

 whole of its food on the ground, is at once driven to 



' In many parts of England most pairs of skylarks have three nests in 

 the year. 



