30 BIRD MIGRATION 



interest in Heligoland is purely ornithological and 

 retrospective. 1 



The little island represents all that remains of a 

 wide tract of land which has been swallowed by the 

 sea. Erosion went on steadily so long as the island 

 was British territory, the west cliff receding seven feet 

 in the forty years preceding the change of ownership. 

 That process must have been arrested when the Ger- 

 mans converted the crumbling rock into a steel-girt 

 fortress. What goes on within the island we have, or 

 had till lately, no means of knowing ; but so long as it 

 continued under the British flag it served as a resting- 

 place for millions of migrating birds, which remained 

 faithful to the traditionary route adopted tens of thou- 

 sands of years ago when a vast plain occupied the 

 space no\v filled by the North Sea. Previous to 1890 

 the birds used to arrive in such countless flocks that 

 their capture afforded chief means of livelihood to a 

 large proportion of the population. One of these 

 islanders, Heinrich Gatke by name, spent fifty years of 

 his life, not only in shooting and trapping the migrants, 

 but in keeping a valuable record of the dates of their 

 arrival and departure. His notes were embodied in a 

 volume in 1895, which has added materially to our 

 knowledge of bird-movement, showing that many 

 species, formerly regarded as stationary and permanent 

 residents in our islands, do in fact migrate seasonally 

 and as regularly as the woodcock and the wildgoose. 



Take, for example, the smallest of all British birds, 



1 This note was written before the Great War, in consequence 

 whereof the fortifications have been razed. 



