BIRD MIGRATION AT HELIGOLAND. 167 



1 male ; Anas perspicilata, 1 male ; Larus affinis, J male ; L. 

 Rossi, 1 male. To these may be added, Sylvia superciliosa, 11 ; 

 Anthus Richardi, 20 at least ; Alanda brachydactyla, the same 

 number; and Emberiza pusilla, 10. Together 140 birds, every- 

 one of which I had fresh in my hands, and ascertained their sex 

 by dissection. 



Young birds of the age of one year or less, of the south- 

 eastern species enumerated in the foregoing list, have been 

 obtained here in very rare instances ; they are : — Falco rufipes, 

 once ; Pastor roseus, 6 young grey birds ; Turdus saxatilis, 1 in 

 first autumn ; Sylvia viridanus, 1 in first summer ; Saxicola 

 deserti, 1 in first autumn ; Emberiza melanocephala, 1 in first 

 summer, 1 in second summer; Charadrius caspius, 1 in first 

 autumn ; Alauda brachydactyla, 1 in first autumn. 



With the exception of a few American birds, the accidental 

 visitors are divided, according to season, strictly into two groups, 

 viz., those which come from the far east and east-north-east, and 

 those whose home lies in a south-eastern direction — Greece, Asia 

 Minor, Palestine, Turkestan. The former appear almost without 

 exception in autumn, the latter quite as exceptionally from the 

 end of May to the end of July ; the former, like all autumnal 

 migrants, consisting of about two-thirds of young birds, from 

 two to three months old, whilst the latter are represented almost 

 exclusively by old birds, and principally by the finest old males. 

 Both movements are favoured by light south-east winds and fine 

 warm weather. What, however, causes a small number of indi- 

 viduals of these eastern species to give way to meteorological 

 influences, and adopt a western flight instead of their normal 

 southern autumnal migration, would be very difficult to say. It 

 would seem easier to solve the question respecting those visitors 

 from the south-east which appear during the breeding-time, and 

 nearly all of them being fine adult birds ; the approximate con- 

 clusion is, that they are individuals which have lost their mate at 

 a more or less early period of their nesting, and, the impulse of 

 propagation being not yet extinct, they resume their inherent line 

 of spring migration, being in their case towards the north-west, and 

 so pass on to Germany and England. This view of the case is sup- 

 ported by the fact that the greater number of these birds are very 

 fine old males; the females on the nest being more subject to 

 destruction by their manifold enemies. Further support of this 



