THE BIRDS OF HELIGOLAND 271 



89. — Wolf's Bluethroat [Wolf's Blaukehlchex]. 

 SYLVIA WOLFII, Brehm.i 



• Helijiolandish : All-Heel blii Bluhemmel lnnk = Entirely bine Skybird 

 Sylvia woljii. Nanniann, xiii. 377, aud Blasius, Nachtrdge, 59. 



Cyanecula wolfii. Dresser, ii. 311. 



On the 30th of March 1848, there Avas shot on Sandy Island a 

 Bkiethroat liaving its upper breast of a unifonn bkie, and showing 

 even on raising the feathers no trace of white beneath, the basal 

 portions of all the blue feathers being of a uniform grey. The bird 

 was a fine old male, and this is the only instance of my having 

 obtained one. In three other instances I have obtained in the 

 spring males with the upper breast of an apparently uniform blue, 

 but in all these a small round brilliant white spot either became 

 visible at once after a slight displacement of the feathers, or could 

 be seen gleaming more or less distinctly through the blue covering 

 feathers, even when these were left undisturbed. 



I have followed Naumann in citing this uniformly blue form 

 of Bluethroat as a separate species, inasmuch as Heligoland does 

 not supply sufficient data towards settling the question as to 

 whether it is to be considered an independent species or not. The 

 fact that the present form occupies similar areas to that of the 

 white spotted one, and inter-breeds with the latter, can hardly 

 justify us in disputing its claim to be regarded as an independent 

 species ; on the other hand the circumstance that, despite such 

 crossing, both forms maintain their purity, should rather be accepted 

 as evidence in favour of their independence. 



However, only such individuals in which the basal portions of 

 all the blue feathers are of a uniform gi'ey, ought to be regarded as 

 Sylvia v-olfii, while the least indication of a small white spot on 

 the upper breast should be considered as the mark of a mongrel, 

 in the same way as in the case of the Carrion and Hooded Crows. 



According to all that has hitherto been observed and reported in 

 respect to this species, Germany is to be regarded as its principal 

 breeding area; it is there that uniformly blue-marked old males 

 have been met with in greatest frequency during the breeding 

 season. It is however probable that its nesting stations extend 

 considerably farther, both west and east, for Howard Saunders 

 obtamed in Spain a pair of apparently blue individuals, wkich, how- 

 ever, on raising the feathers of the upper breast, displayed a small 

 white spot, and were accordingly mongrels. Still, their occurrence 

 ' Cyanecula ivoljii (Brehm). 



