428 CORACIIFORMES CHAP. 



-even -in snowy weather, while Oreotrockilus chimborazo and 0. 

 pichincha brave the storms of the volcanic regions of the Andes 

 of Ecuador, close to the perpetual snow at a height of sixteen 

 thousand feet. The forms found in the furthest north and south 

 .are few, and draw towards the equator at the cold time of year ; 

 while the successional flowering of insect-attracting plants, and 

 the seasonal alteration of the snow-line, cause latitudinal or alti- 

 tudinaj movements of the same nature. Only eighteen species are 

 recognised as occurring north of Mexico by New World ornitholo- 

 gists, but many more inhabit Central America, which are either 

 peculiar to that region and even its elevated tablelands, or range 

 into South America ; none, however, being migrants in the strict 

 sense of the word. The headquarters of the Family lie in 

 Colombia and Guiana, though Venezuela, Peru, Bolivia, and 

 Brazil claim many, and some of the finest, forms : on the other 

 hand, the dry Peruvian plains and the Argentine Pampas lack 

 sufficient insect-food to be favourite residences. With regard to 

 the West Indies the numbers increase from the Bahamas to 

 Trinidad, each island often having its own species ; EustepKanus gal* 

 eritus, E.fernandensis and E. leyloldi occupy the Juan Fernandez 

 group, and the first-named Chili and the Straits of Magellan 

 also. Humming-birds may be roughly divided as alpine, sub- 

 alpine, and lowland, while it may be noticed that comparatively 

 few inhabit the great forest-clad delta of the Amazon, the 

 congenial centre of so much bird-life. 



The Trochilidae live almost entirely in the air, and fly power- 

 fully, though seldom to great distances ; they will flit from flower 

 to flower for hours, darting off to each new blossom with arrow-like 

 speed, and remaining suspended before it, with the body vertical 

 .and the wings in a state of tremulous motion, while probing 

 the inmost recesses. This is commonly accompanied by a vibra- 

 tory movement of the tail, which in some cases opens and shuts 

 like a fan. The humming sound, produced at each new depar- 

 ture or change of course, and audible for several yards, is due to 

 a pulsation of the wings, so rapid that little can be seen of the 

 bird but an indistinct misty outline. Messrs. A. and E. Newton 

 give the following charming account of Eulampis holoseri- 

 ceus * : " One is admiring the clustering stars of a Scarlet 

 Cordia, the snowy cornucopias of a Portlandia, or some other 



1 Ibis, 1859, pp. 139, 140. 



