THE BIEDS OF HELIGOLAND 177 



This results from the simple fact that the western limit of their 

 breeding range extends, not considering extralimital exceptions, 

 from Greece through Hungary to the region of the Dwina, while 

 their winter quarters stretch through Africa as far south as Damara- 

 land, where they are reported as occurring in flocks amounting to 

 tens of thousands. Damaraland is almost in the same meridian as 

 Greece and Hungary. This would likewise explain the very rare 

 occurrence of this Falcon in Heligoland, because this island lies to 

 the west and outside of its line of migration. It is, however, difficult 

 to reconcile with this view its numerous appearances in England 

 [Britain], where, according to Harting {Handbook of British Birds, 

 p. 86), it has been observed twenty-nine times between May 1830 

 and October 1868. The only way out of the difficulty would be to 

 accept Dresser's statement to the effect that the birds also nest in 

 Algiers, though this is doubted by Seebohm. If Dresser be correct, 

 the birds which reach England, like all exceptional occurrences 

 during the summer months, would be individuals which had lost 

 their {jairing-spouses during the first stages of the breeding season, 

 but strove to appease the unsatisfied breeding instinct by continu- 

 ing their journey in the direction of the normal spring migration of 

 the species, viz. northwards across France to England. 



In the portion of this book which deals with Migration in 

 general (Part i.), I have sought, by citing many instances, to 

 establish this idea, as one solving the question of exceptional occur- 

 rences during the summer. 



Seebohm (British Birds, i. 42) gives the Jenisei as the eastern 

 boundary of the bi'ecding range of this species : in Turkestan, 

 it appears, according to Sewertzoff, to be a common migrant. In 

 India, however, not many of these birds pass the winter : at this 

 season, indeed, they are nowhere met with so abundantly as in 

 Lower Africa, where, as already stated, the flocks are said to number 

 tens of thousands of individuals. 



12. — Golden Eagle [Goldadler]. 

 FALCO CHRYSAETUS, Linn.i 



Falco chrysaetus. Nauiiiann, xiii. 8 ; Blasius, Naclitnigi', 7. 

 Golden Eagle. Dresser, v. 533. 



The true eagles, feathered do^vn to the toes, count among the 

 rarest occurrences of Heligoland. So far as observations go, the 

 bird has only reached the island four times within the last forty 



' Aquila chrysaiitoii (Liun.). 



