136 TROPICAL NATURE, AND OTHER ESSAYS. 



ming-birds have more or less the habit, when in flight, 

 of pausing in the air and throwing the body and tail 

 into rapid and odd contortions. This is most observable 

 in the Polytmus, from the effect that such motions have 

 on the long feathers of the tail. That the object of these 

 quick turns is the capture of insects, I am sure, having 

 watched one thus engaged pretty close to me. I observed 

 it carefully, and distinctly saw the minute flies in the air 

 which it pursued and caught, and heard repeatedly the 

 snapping of the beak. My presence scarcely disturbed 

 it, if at all." 



There is also an extensive group of small brown hum- 

 ming-birds, forming the sub-family Phaethornithinse, 

 which rarely or never visit flowers, but frequent the 

 shady recesses of the forest, where they hunt for minute 

 insects. They dart about among the foliage, and visit 

 in rapid succession every leaf upon a branch, balancing 

 themselves vertically in the air, passing their beaks 

 closely over the under-surface of each leaf, and thus 

 capturing, no doubt, any small insects that may lurk 

 there. While doing this, the two long feathers of the 

 tail have a vibrating motion, serving apparently as a 

 rudder, to assist them in performing the delicate opera- 

 tion. Others search up and down stems and dead sticks 

 in the same manner, every now and then picking off 

 something, exactly as a bush-shrike or a tree-creeper 

 does, with the difference that the humming-bird is con- 

 stantly on the wing ; while the remarkable Sickle-bill is 

 said to probe the scale-covered stems of palms and tree- 

 ferns to obtain its insect food. 



It is a well-known fact that although humming-birds 

 are easily tamed, they cannot be preserved long in 



