102 HABITS AND INSTINCTS OP ANIMALS. CHAP,, IV. 



that period of the day when they feed ; for, at other 

 times, it is a common thing to see them perched upon 

 naked branches of trees : but the frigate-birds are always 

 upon the wing \ they, as well as the albatross, are often 

 met with many hundred miles from any land. Fur- 

 thermore, the one pursues or hunts after the flies on 

 which it feeds; the other rather watches for the appear- 

 ance of fish near the surface, while soaring in mid air, 

 and then only pounces or drops on its prey. It is 

 interesting to notice these variations in the habits of 

 two families of birds, totally different from each other 

 in general structure and habits, and yet possessing in 

 common a superiority of flight over almost all others 

 of their own class. 



(124.) To some few genera of birds, the powers of 

 flight are either partially or totally denied : these are 

 chiefly found among the rasorial groups, and some few 

 of the aquatic order. In the first, we have the different 

 ostriches of the Old and the New World, as well as the 

 emu of Australia, in all which the wings are merely 

 rudimentary ; and although of some little assistance in 

 aiding their running, cannot raise the bird above the 

 level of the ground. Yet here, again, we see the wise 

 provision made by their Almighty Creator, in insuring 

 the safety of birds whose wings are useless. In the 

 frigate pelicans, just mentioned, we have an example 

 of the highest development of wing, joined to feet of 

 the most imbecile and abortive structure. In the os- 

 trich, on the other hand, these gifts are exactly re- 

 versed ; the wings are, in a manner, useless ; while the 

 feet, strong and robust, more resemble those of a horse 

 than of a bird, and enable the ostriches to course over 

 their native plains at so prodigious a rate, that a horse- 

 man is often obliged to give up their chase in despair. 

 The whole structure, in short, of these birds, as regards 

 locomotion, is formed for running instead of flying ; 

 while the great elevation of the head, occasioned by 

 their very long neck, enables them to discover, on the 

 level plains to which they confine themselves, the ap- 



