200 



BRITISH BIRDS. 



to snatch its swimming prey, the legs are dropped, and 

 the moment the quarry has been seized, if not before, 

 the feet are phed vigorously to run along the surface of 

 the water, and thus not only act as buffers and prevent the 

 body from striking the water, but also help to increase 

 the velocity necessary- to enable the bird to rise again. 

 In Figure 3, although the feet of the Kittiwake have 

 ceased to touch the surface, the bird is still running, as 

 it were, in space. 



FIGURE 3. — RUNNING, AS IT WERE, IN SPACE. 

 {Photographed by Bentley Beetham.) 



Another method often practised by birds to lessen 

 speed is that of depressing the tail, and so offering a 

 resistance to the air rushing along the under-surface of 

 the body, and this is illustrated in the Gannet shown in 

 Figure 4. This use of the tail is ver}^ similar in its 

 purpose and result to the use of the feet as brakes. 

 Steering is also, of course, aided by the tail, it being 

 visiblv turned from side to side, raised or depressed, 



