50 THE BIRDS OF HELIGOLAND 



Instance after instance might be cited in support of what has 

 been said above ; we shall, however, let one suffice, and that the 

 case of a bird which may appear little adapted for a soaring flight 

 of this kind to wit, the Golden Plover. In the autumn, Avhen the 

 young birds of this species are shot here, it is usual to decoy them 

 within range by imitating their call-note. The birds, though in 

 other respects not particularly distrustful, are rendered shy through 

 being repeatedly shot at, and in consequence fly to heights beyond 

 shooting range ; nevertheless, they may be lured back to the desir- 

 able distance by the stratagem above referred to. When the birds 

 decoyed in this manner have come into a position in the air nearly 

 vertically above the head of the shooter, they almost invariably 

 remain soaring, with calmly outspread wings, for a shorter or longer 

 time over the same spot, spying downwards and answering the 

 feigned call-notes, until, discovering that they are not those of their 

 kindred, they quickly hasten off with rapid beatings of the wings. 



These birds are almost without exception well nourished, and 

 their weight is, in proportion to the surface-area of their wings, so 

 considerable, that, unless they were supported by other accessory 

 means, they would, in the absence of any movement of their wings, 

 be at once obliged to sink. These means, in the present case, how- 

 ever, neither consist in any rapid movements on the part of the 

 birds, as already stated above, nor in air-currents, since the shooting 

 of these birds, as a rule, only goes on in fine and perfectly calm 

 weather. 



All attempts with which I am acquainted, to account for the 

 flight of birds, are based on the assumption that birds are able both 

 to maintain themselves suspended in the air as well as to move for- 

 ward in it, either by continuous more or less rapid movements of 

 their wings, in the same way as a man uses his arms in swimming, 

 or that the same end may be attained without these continuous 

 wing-movements, through the agency of a current of air of sufficient 

 strength ; but that, without either the one or the other of these 

 conditions, flight is an impossibility. Captain F. W. Hutton says 

 in his Mechanical Principles involved in the Sailing-flight of 

 the Albatross : ' In a perfectly calm atmosphere an Albatross 

 with outspread wings would drop unless it was also executing a 

 forward movement.' 



My own unremitting observations, however, extending over a 

 lifetime, aided by an artist's eye specially trained for form and 

 motion, and subjected to the most severe self-criticism, are so much 

 at variance with all explanations based on mechanical laws, of the 

 kind referred to above, that I am obliged to consider the question 

 of bird-flight, as yet, as an unsolved and perfectly open one. 



