50 



Heligoland. Still for all that, such a contingency occasionally 

 happens in the autumn months. In such instances the explana- 

 tion, to the writer, seems to be that these stragglers have 

 accidentally attached themselves to flocks of other species whose 

 ordinary flight passes the island. 



In the ease of the Yellow-headed Wagtail, it may be remarked 

 that up to the present this species has not been found breeding 

 west of the valley of the Petchora. That it should have occurred 

 on migration no less than five times in so distant a locality as 

 Heligoland is remarkable, and forms additional proof that many 

 of the migrants — which according to Gatke, are derived from the 

 east — really come from northern and north-eastern regions. 



The above remarks also apply to the Siberian Chiff-Chaft' and 

 Yellow-breasted Bunting ; though their breeding ranges extend 

 further west. The latter species, it may be noted, has occa- 

 sionally been found in Southern Europe. 



As an exception to the rule of a migration rigidly performed 

 betw^een the points of north and south, or rather in accounting 

 for the regular appearance on Heligoland and in other parts west 

 of the ordinary limits of such a flight, Herr Gatke makes especial 

 reference to the Little Bunting. On page 34 this species is said 

 to migrate in a direct north-to-south line of flight, but later on in 

 his work the author includes it amongst those which are supposed 

 to migrate westward from Eastern Asia. On page 34 he remarks : 

 " More or less considerable numbers of individuals turn to the 

 west on quitting their nesting stations, and migrate to Western 

 Europe instead of Southern Asia." He further adds : " This 

 tendency is by no means peculiar to those species whose breeding 

 range extends to Western Asia or North-eastern Europe, as is 

 proved by the cases of the Siberian Chiff-Chaff, the Yellow- 

 breasted Bunting, and the Terek Sandpiper. On the contrary, 

 all our experience goes to show that it is more especially mani- 

 fested by species whose breeding homes are furthest removed 

 from Europe. . . . Moreover this tendency is generally confined 

 to particular species only of a genus, being entirely absent in 

 others of the same genus. In proof thereof we may cite the case 

 of the Yellow-breasted Bunting and the Little Bunting — two 

 species breeding in the north-east of European Eussia, whose « 



