CHAP. IV. FLIGHT OF BIRDS. 101 



blown completely out of their native regions, or be 

 exhausted by fatigue before they could reach a place of 

 shelter. The genera which comprise the albatrosses and 

 the frigate-birds stand at the head, in this respect, of the 

 aquatic order, and show us a remarkable development 

 of flight. The manners of the latter we never saw to 

 more advantage than in the magnificent harbour of Rio 

 de Janeiro. It was, indeed, an imposing sight, to con- 

 template half a dozen of these aerial birds soaring in 

 mid ah*, and then, in an instant, as if shot, falling down 

 with a splash into the sea upon a shoal of fish. At 

 other times, during a storm, they soar to such a height, 

 that, notwithstanding their size, they appear but as 

 specks in the firmament : all their powers of motion, 

 in fact, seem to be concentrated in their wings ; for the 

 feet are so short and weak (as in nearly all of the same 

 order), that, when upon the ground, they may be ap- 

 proached with ease, for they can scarcely walk, and 

 take a long time, comparatively, to mount on their 

 wings. The tropic-bird flies as high as the frigate 

 pelican ; but its range is more confined to certain lati- 

 tudes, and its wings are not more developed than those 

 of an ordinary gull. All these birds occasionally, in 

 calm weather, rest themselves, after the bufferings of a 

 storm, on the sea ; but they are obviously not qualified, 

 from the smallness of their feet, to make much way by 

 swimming. 



(123.) The flight of the typical swallows, as well 

 as of the goatsuckers, is, perhaps, more rapid than that 

 of the oceanic birds ; but we question, notwithstanding 

 their migrations, whether it is so long sustained^ al- 

 though it is obviously accompanied by much greater 

 muscular exertion. The flight of the albatross and the 

 frigate-bird is accomplished with scarcely any motion 

 of the wings : they may be said to balance themselves 

 in the air, rather than to use the ordinary exertion at- 

 tendant upon flying : neither do they make those rapid 

 evolutions which characterise the land birds we are now 

 speaking of. Flight, in the swallows, is confined to 

 H 3 



