26 INTRODUCTION. 



recent scientist gives it as a general rule that the larger the "bird 

 the smaller, comparatively, are its wings. Thus, the sparrow, 

 which weighs 339 times less than the Australian crane, has 

 proportionately seven times more wing surface. Yet the crane 

 has few equals in the height to which it rises, or the length of 

 time its flight is maintained; while of all migratory birds it 

 probably takes the longest journeys. 



The form and size of the wing differs considerably in different 

 species, and on these depend the flying powers of the bird. 

 Thus long, narrow, sharp-pointed wings are associated with the 

 highest powers of flight ; while with short, rounded wings the 

 flight may be rapid, but never long sustained. 



The coot, diver, duck, and goose are examples of short-winged 

 birds which fly with great rapidity ; but, as speed is attained by 

 the constant flapping of the wings, the severe muscular strain 

 tires them sooner out. The "poetry of motion," as flight has 

 been called, is best seen in the "sailing" birds, which include 

 those provided with long, sharp-pointed wings. One of the best 

 examples is the albatross, with its great, narrow wings, about 

 fourteen feet from tip to tip, and only a foot in breadth. To rise 

 from the water this huge bird has to flap violently on the 

 surface with its wings, and for some time after it is fairly out of 

 the water. Once launched, however, all visible exertion ceases, 

 and with outstretched, motionless wings it sails along with 

 majestic sweeps. "I have," says Captain Hutton, "narrowly 

 watched one of these birds sailing and wheeling about in all 

 directions for an hour without seeing the slightest movement of 

 the wings ; and have never seen anything to equal the ease and 

 grace of this bird as it sweeps past, often within a few yards — 

 every part of its body perfectly motionless, except the head and 

 eye, which turn slowly and seem to take notice of everything." 

 But this sailing motion is only possible when there is a breeze ; 

 when calm it sits on the water, or if it rises, it has to flap its 

 monster wings continually. It is like the sailing boat which 

 glides swiftly before a favouring breeze, but must be propelled 

 by oars in a calm. 



That a breeze is essential to the sailing or soaring of birds 

 was also the opinion of Belt, who, in his "Naturalist in 

 Nicaragua," states that " when it is calm the vultures are obliged 

 to flap their wings when they fly, but when a breeze is blowing 

 they use their specific gravity as a fulcrum, by which they 

 present their bodies and outstretched wings and tails at various 

 angles to the wind, and literally sail." I have repeatedly seen 



