MAN AND ANIMALS. 203 



should, according' to all the evidence that we have, 

 be most energetic also. 



But though here, as in all cases, man must be put 

 aside as being- over the system, not of it, the rest of 

 the system in these^beaming and blooming lands works 

 vigorously and, at the same time, beautifully in con- 

 cert. The birds may, in all countries, be regarded 

 as the keys to natural history ; because in conse- 

 quence of their aerial nature, and their capacity of 

 better accommodating themselves to such food as 

 they may find when they are very hungry, they can 

 so speedily adjust themselves to changes of season, 

 that the adjustment is made before we are aware of 

 the necessity for making it, as the bird is to us the 

 harbinger of that very change in nature, of which its 

 change of place or of action is the consequence. 



There are no places to which the native birds are 

 better keys than the tropical forests. The great 

 majority of them — all this order, with the very few 

 exceptions which have been noticed, are forest birds 

 either on the trees, or passing from tree to tree, or if 

 they feed on the ground in the open places, not 

 ranging on foot, as the ground birds of our latitudes 

 do, but finding a full meal at the places where they 

 alight. 



The vegetation of every region determines the 

 character of all its living inhabitants, and though the 

 birds, as the most sensitive to change, are the keys or 

 indices, the vegetable tribes are the foundation of the 

 whole, which support many of the animals imme- 

 diately, and the rest indirectly through the medium of 

 each other. There are few small farinaceous seeds 

 in those forests ; and the leaves of the trees are not 

 so succulent and so well adapted for the food of 

 insects as the deciduous leaves of the mean latitudes. 



