LOCALITIES OF THE BIRDS. 
69 
is the case with the mammals, their habitat depends upon the presence 
of vegetable life; and it is in the bosom of the forest that the bird 
appears in all his glory. The ocean-birds may be counted by thou- 
sands and tens of thousands ; and when the mating-season arrives, 
they gather along the shores and upon the rocks in innumerable bands 
— a whole legion sometimes being composed of individuals of a single 
species. On land, and mainly in the forests, we meet with companies 
almost as numerous, and represented by the most diverse forms. The 
nearer we approach the Equator, the more the species multiply. In 
tropical lands, the conditions of existence are more varied than in our 
sober, temperate climes; and so, too, are their physical aspects. Nature 
is more exuberant ; life teems and swarms and runs riot. The greatest 
variety of species, however, does not occur in the virgin forests, but in 
those regions where alternate the woods and the fields, the mountains 
and the valleys, the arid table-lands and the reeking marshes. 
Wherever a river rolls its copious waters through the forest shades ; 
wherever a morass is surrounded by a belt of trees ; or wherever the 
inundated plains enclose an isolated patch of copse and thicket, — in 
such places the greatest number of species is met with, because in such 
places they find a more abundant nourishment than is elsewhere 
obtainable. On the facility with which they can secure their food 
