I 97 



other places is said to be conducted no further than the west of 

 Central Norway (p. 66). It will be also gathered "that the 

 species does not winter further west than Central Africa, nor do 

 its breeding quarters extend further to the westivard than Norway, 

 there can therefore be no doubt as to the identity of the examples 

 found in Heligoland with those from Central Africa," (p. 66). 



Before discussing in detail these various passages in the life- 

 history of the Bluethroat as observed at Heligoland, it will not 

 be inappropriate to remind the reader of Herr Gatke's own words 

 (p. 59) on the danger "of basing on observations of this nature 

 the line of arrival or the migration-front of a species, or to 

 draw conclusions from them, as to the velocity of the migration 

 flight," &c., &c. 



First in order, it will be as well to again examine the evidence 

 in favour of a rigidly performed flight from north to south or the 

 reverse, according to the seasons, for in the opinion of the author 

 this is only departed from in the rarest instances, and it is on the 

 accuracy of this theory that his estimates of the velocity attained 

 are in the main dependent. Writing on the autumnal flight he 

 remarks (p. 37) " It hence follows most decisively that the bird, 

 in autumn, rigidly adheres to a southerly course of migration, 

 and travels in a broad migratory front which corresponds to the 

 longitudinal range of its nesting area, and of which Heligoland 

 forms the most western limit. Even a slight westerly deviation 

 from their southerly course of such species (individuals?) as 

 breed in the west of Norway could not fail to convey large 

 numbers of these birds to the east coast of England, and their all 

 but total absence there furnishes therefore an undoubted proof of 

 the persistency with which the southerly course of migration is 

 in this instance adhered to." As previously observed, Herr 

 Gatke's information relating to England is quite at fault, for 

 recently hardly a year passes without records of the occurrence 

 of the Bluethroat on our east coast curiously enough, many of 

 them coming from the pen of Mr. John Cordeaux, to whose notes 

 he so frequently refers. He has also quite ignored the consider- 

 able flock which arrived on the north Norfolk coast in September, 

 1883, though the latter fact is fully recorded in the reports issued 

 by the Committee on the Migration of Birds, and he himself 

 7 



