POSITIONS ASSUMED BY BIRDS IN FLIGHT — BEETHAM. 439 



top of the column of rock, the base of which is vaguely suggested at 

 the left-hand side of the print. Each time the bird approached its 

 method was the same. It flew along the cliff-face until it reached a 

 point nearly opposite to the nest, but considerably below it; then it 

 swept round abruptly until it faced the cliff, at the same time giving 

 its course a strong upward tendency, still trailing its feet. Plate 7, 

 figure 1, shows the bird just after it had faced round to the cliff and 

 was sweeping upward. As soon as it arrived directly opposite to its 

 nest, its one thought was to stop the forward and upward impetus 

 produced by the great soaring approach. 



Plate 7, figure 2, shows plainly the measures adopted by another 

 bird — which, by the way, advanced in a more direct and horizontal 

 course, and had, therefore, a more direct forward momentum to 

 counteract. It flew straight for its nest, sweeping slightly upward 

 until it found itself almost opposite the place, and perhaps some 5 or 6 

 yards distant from it. Then by a dexterous turn it .threw the plane 

 of its great surface into a vertical position and at right angles to the 

 direction of its course, thus offering the maximum amount of resist- 

 ance possible. The whole area of the wings, body, and tail is directly 

 opposed and spread out to resist the bird's forward passage through 

 the air, and it is interesting to note how the tail has been extended 

 to the utmost, fan wise, so as to increase as much as possible the 

 effective area. It will be noticed that the feet are thrust forward 

 and the webs extended in anticipation of the coming contact. That 

 a great strain is being placed upon the wings and that therefore a 

 great resistance is being encountered is indicated by the curve of the 

 primaries. 



Plate 8, figure 1, shows the position a moment later. The bird 

 has now got its feet upon the rock (or rather one foot, for the other 

 is thrust out horizontally on the nest, having no doubt missed its 

 mark, and can be of little, if any, support) , and appears to be almost 

 stationary, but as a matter of fact it has still a forward impetus which 

 the raised wings are trying to counteract. The bird has, indeed, 

 just set foot upon the ledge, and is falling forward in the direction 

 of its approach. 



The last photograph (pi. 8, fig. 2) again carries us on a brief moment. 

 Now the bird has pitched forward on to its breast, its wings having 

 failed to find sufficient resistance in the air to counteract the body's 

 momentum, and in consequence the wings have come crashing down 

 upon the rocks at the end of their strenuous beat. The position of the 

 tail is interesting; in plate 7, figure 2, it is seen fully expanded and 

 depressed in order that its ventral surface may oppose the forward 

 progress, and now it is turned upward above the back so that its dor- 

 sal surface may find resistance and try to counteract the tendency 

 to pitch forward on to the breast. 



