340 THE BIRDS OF HELIGOLAND 



latitudes but not within the very broad belt intermediate between 

 these. 



Several authors make note of indications of white eye-stripes 

 in the Black-headed AVagtails. These, however, would seem to be 

 rare ; for among the numerous examples obtained here during the 

 long period of fifty years, I have scarcely met with more than two . 

 or three birds which displayed from three to four small white 

 feathers, for the most part on one side of the head only. The only 

 conclusion which it seems to me permissible to draw from this 

 circumstance is that inter-breeding must sometimes, even if only 

 extremely rarely, take place between this species and M. flava, 

 resulting in the production of mongrels having the last-named 

 peculiarity. Frequently, also, one finds among both species fine old 

 males having on the occiput scattered yellow feathers intermingled 

 with the normally coloured ones ; these, however, must be regarded 

 as merely accidental features. In individuals of this kind the yellow 

 colour of the lower parts is almost invariably of very great 

 intensity. 



The individuals of this species, which it has been thought 

 fit to separate under the name of M. viridis = cinereoccqyilla, 

 breed from central to upper Scandinavia, and within the same 

 parallels of latitude as far as eastern Asia. In a few old males of 

 these the crown of the head is of a slaty-blue grey. Of those 

 nesting in Italy, Greece, and as far as Turkestan, the males are 

 said invariably to have the crown perfectly black in the breeding 

 plumage. 



Another black-headed species, in which the males however have 

 a pure white eye-streak is, according to Blasius (Supplement to 

 Naumann), resident in soutliern Kussia and Dalmatia, and has 

 been shot by Finsch on the Obi. 



151. — Yellow Wagtail [Grunkopfige Bachstelze]. 



MOTACILLA KAYl, Bonaparte.' 



Heligolandish : Giihl-hoaded GnbXblahheT = Ydlow-headed Wagtail. 



Motacilla flaveola. Naumann, xiii. ; Blasius, Nachtriige, 129. 



Yellow Wagtail. Dresser, iii. 277. 



Bergeronnetteflaveole. Temminck, Manuel, iii. 1S3. 



This handsome Wagtail arrives here with every sjjring migration; 

 for the most part, however, only single individuals are met with, — 

 three or more on the same day being an exceptional occurrence. 

 Their migration commences very early ; one might almost say that 



J MolaciUa rail, Bp, 



