THE BIRDS OF HELIGOLAND 269 



Young autumn birds have not even a tinge of rust colour, 

 either on the throat or fore-neck ; but these parts are pure white, 

 with the exception of a more or less compact deep black baud on 

 the upper breast, which is prolonged upwards along both sides of 

 the neck. It is rare to meet with old males in autumn plumage in 

 which the spot on the neck is entirely rust colour, its upper half 

 being almost always of whitish coloration. 



A mere superficial inspection of examples of the last kind of 

 aberration from the normal spring plumage of the male discussed 

 above, might easily lead one to suppose that such birds were 

 hybrids of the present and following species. The possibility of 

 such an intermixture is however excluded by the mere fact that the 

 one species breeds within the area of the Arctic Circle, or in 

 northern mountain chains, at heights possessed of an arctic climate, 

 while the other does not extend beyond the North Sea and Baltic, 

 and remains permanently on the plains. 



Here in Heligoland, too, the time of the spring miga-ation of the 

 two species very clearly demonstrates the wide distance, comprising 

 many degrees of latitude, which separates their homes. The more 

 southern breeding stations of the white-spotted species become 

 haljitable at a very early period of the year, and accordingly the few 

 individuals which ever reach this island arrive as early as the end 

 of ilarch, or during the first days of April ; at that time winter 

 still completely reigns in the nesting area of the northern species, 

 and does not yield to milder weather until three or four weeks 

 later ; accordingly, the spring migration of this latter species does 

 not take place until May. 



88. — White-spotted Bluethroat [Weiss-sterniges 

 Blaukehlchen]. 



SYLVIA LEUCOCYANA, Brehm.^ 



Heligolandish : Wit Blii-Heininel-Fiiik= Uliite-Blue Skybird. 



Sylvia suecica. Naiiiiiann, ii. 414. S. Icuocymia, xiii. 373, and 



Blasius, Nachtriige, 59. 

 White-spotted Bluethroat. Dre.s.ser, ii. 311. 

 Bee-fin gorge bleue. Teiiiniinck, Manuel, i. 216. 



This elegant bird, with the pure white satiny throat-spot on a 

 field of blue, is one of the rarest of occurrences in Heligoland. 

 With one sole exception, it has occurred here only at intervals 



' Cyanecvla teucocyana (Brehm). 



