356 THE STRUCTURE AND LIFE OF BIRDS chap. 



spot. Gilbert White wondered at the annual return 

 of the same number of Swifts each year (exactly 

 eight pairs) to Selborne. And now it has been put 

 beyond a doubt that many migrants return to their 

 old nesting-place. When a Nightingale in Abyssinia 

 is seized with the migratory impulse, his heart is filled, 

 not with a vague yearning for the north, but with a 

 yearning for one familiar spot. 



The Time Occupied in Migration. 



The flight in spring is generally, as I have said, 

 more rapid than in autumn. In spring the birds have 

 a definite purpose before them. They wish to set 

 about their nest building, and they grudge every hour 

 of delay. In autumn they pause and loiter in Central 

 and even in Northern Germany. It is difficult to 

 estimate the exact time occupied by the spring flight > 

 but some evidence is obtainable. That particular 

 form of Bluethroat that has a red spot in the centre 

 of the blue, winters in Egypt, often in the regions of 

 the Upper Nile. It occurs frequently in Heligoland, 

 whereas in Germany only the form that has a white 

 spot is found. Since, then, according to the evidence, 

 Heligoland is the first place at which it stops as it 

 travels to its breeding stations in Northern Scandi- 

 navia and Russia, it would seem that it covers the 

 whole distance from Egypt to Heligoland — over 1,500 

 miles — in a single flight. This is very difficult to 

 believe, and to follow Herr Giitke when he maintains 

 that the flight is accomplished in a single night is still 

 more difficult. As evidence, he mentions the interesting 



