ANIMAL FLIGHT II3 



hence the albatross is exclusively a bird of the windier regions 

 of the oceans. He can only exist where the wind is always 

 strong and the waves are always high. The calm belts of the 

 tropics form an impassible barrier for him, and he cannot fly for 

 any appreciable distance over land. The stormy southern 

 oceans and the equally boisterous north Paciflc are his home, 

 but no one kind exists in both these places. He cannot live 

 in the tropic calms, nor in the relatively calm North Atlantic. 



Quite a number of smaller sea birds ranging in size from the 

 giant fulmars down to the smaller shearwaters have the same 

 habit of flight as the albatross, and are quite as good fliers 

 as is he; but for the most part they are smaller with 

 broader wings and can fly well in winds so light that they 

 would not serve the albatross at all, and they can also fly well, 

 though with much flapping, during calms. 



When a strong wind strikes a cliff a considerable amount of 

 air is deflected upward forming a column or wall of air for a 

 considerable height above the top of the cliff. Such a mass of 

 rising air is favorite play-ground for birds which soar above it 

 just as other birds do in the columns of warm air rising from 

 the hot tropical lowlands. At Agattu Island in the western 

 Aleutians where the sun very rarely shines — ■ there is no record 

 that anyone ever saw the sun there — but where the wind 

 always blows there is a cliff" near the anchorage on and near 

 which aU sorts of birds abound. When the wind blows against 

 this cHff the air above it becomes filled with birds, some merely 

 flying back and forth, like the puffins, murres and guillemots, 

 but others wheeling and soaring like hawks. Most conspicuous 

 among these soaring birds are the geese, cormorants and ravens, 

 birds which ordinarily we never think of as indulging in diver- 

 sions of this nature. The gulls, too, are very numerous, but 

 as the gull is an expert balancer and glider it seems only natural 

 that he should be here. 



In mountainous regions there are always strong updraughts 

 of air, both because of the upward deflection of the winds and 

 because of the warming action of the sun's rays. Mountainous 



