106 



by instantaneous photography, that the majority of birds fly with 

 the plane of the body slightly directed upwards. The mainten^ 

 ance of a high rate of speed when a strong wind is blowing from 

 behind, becomes therefore almost a necessity. For whereas the 

 before mentioned position of the body enables a bird in meeting a 

 moderate wind to sustain itself in the air with a minimum of effort, 

 it will have the contrary effect with a wind blowing from behind, 

 unless the speed attained by the bird is much greater than the 

 force of the latter. It is very doubtful, however, whether a poor 

 flier like the Crossbill would have sufficient strength to maintain 

 a great velocity for any length of time. A stiff westerly breeze 

 would not, of course, even approach a force equal to 100 miles an 

 hour. 



Herr Gatke has formed the opinion that birds are not in the 

 habit of breaking their journeys during either migration flight 

 until after the greater part of the distance has been covered. 

 He seems to have come to this conclusion from the fact of the 

 very short stay the great majority of species make on visiting 

 Heligoland. " After a night's incessant flight," he remarks, " a 

 greater or smaller portion of the succeeding day is all the birds 

 need for satisfying their hunger or recovering from such fatigue 

 as may have resulted from the exertions of their journey. I 

 myself have never noticed cases of fatigue or actual exhaustion 

 such as people tell about birds of the Woodcock family on this 

 island, in regard to any birds which have landed here during 

 their migration either by day or night." To the writer, in view 

 of the numbers of dead birds washed up on our shores, and the 

 observations of other ornithologists, amongst whom Mr. Eagle 

 Clarke's remarks are especially interesting (vide "Digest of the 

 Observation on the Migrations of Birds "), the above statements 

 are good evidence that the majority of the callers at the island 

 have travelled over only comparatively short distances prior to 

 their arrival at Heligoland. Indeed, the position of the island, 

 surrounded as it is on three sides by large land-masses at only 

 moderate distances, lends itself to this view. Those species 

 which breed in the north are undoubtedly governed in their 

 forward movement by the early or later departure of winter in 

 the lands towards which they are travelling. The late Mr. 



