90 STRUCTURE AND COMPARISON. 



either be rather slow flyers or else in the habit of soaring, for 

 which they need a large area of wing. But a very long-winged 

 bird, even though its wings are narrow, may be able to soar if, 

 like the albatross and man-of-war bird, its wings are long enough 

 to furnish the required area in sopite of their narrowness. 



In steering the tail does most of the work, though a part of 

 the work is, and the whole may be, done by the wings. Birds 

 making quick evolutions are commonly long-tailed. The terns, 

 goshawk, Cooper's and sharp-shinned hawks are good examples 

 of this. On the other hand, the chimney-swift is rather short- 

 tailed. Birds with short tails and long legs usually trail the 

 legs behind in flight, so that a boy of my acquaintance^described 

 a heron as " a big bird with only one tail feather, which was a 

 yard long.' 7 The loon also, though his legs are not long, 

 stretches them out behind him with the webs of the feet held 

 close together to steer him. Finally, a bird that loses his tail 

 has to learn how to steer himself. A cat-bird that I once knew, 

 having lost his tail by accident, was hard put to tell where he 

 was going until he learned to steer a more certain course with 

 his wings. 



In hovering, also, the tail plays an important part. Watch 

 the humming-bird before the flower, the king-bird over the 

 grass, the sparrow-hawk above the hole of the meadow-mouse. 

 You will see that the tail is held full spread and nearly at 

 right angles to the body, unless the body itself is dropped, as 

 it often is in the humming-birds. Thus the tail holds a large 

 part of the air fanned back by the wings, and acts as a drag 

 on the bird to hold him stationary or nearly so. 



One of the prettiest sights I ever saw was a common tern 

 that, attracted by my fishing, came and hovered within ten feet 

 of me, keenly curious, his scarlet bill and feet, black cap, 

 silvery mantle, and white body gay as a picture against the 



