Humming- Birds. 219 



causes which serve to check variation in all other 

 directions. In their plumage, as Martin long ago 

 wrote, nature has strained at every variety of effect 

 and revelled in an infinitude of modifications. How 

 wonderful their garb is, with colours so varied, so 

 intense, yet seemingly so evanescent ! the glitter- 

 ing mantle of powdered gold ; the emerald green 

 that changes to velvet black ; ruby reds and 

 luminous scarlets ; dull bronze that brightens and 

 burns like polished brass, and pale neutral tints 

 that kindle to rose and lilac-coloured flame. And 

 to the glory of prismatic colouring are added feather 

 decorations, such as the racket-plumes and downy 

 muffs of Spathura, the crest and frills of Lophornis, 

 the sapphire gorget burning on the snow-white 

 breast of Oreotrochilus, the fiery tail of Cometes, 

 and, amongst grotesque forms, the long pointed 

 crest-feathers, representing horns, and flowing 

 white beard adorning the piebald goat-like face of 

 Oxypogon. 



Excessive variation in this direction is checked 

 in nearly all other birds by the need of a protective 

 colouring, few kinds so greatly excelling in strength 

 and activity as to be able to maintain their exis- 

 tence without it. Bright feathers constitute a 

 double danger, for not only do they render their 

 possessor conspicuous, but, just as the butterfly 

 chooses the gayest flower, so do hawks deliberately 

 single out from many obscure birds the one with 

 brilliant plumage ; but the rapacious kinds do not 

 waste their energies in the vain pursuit of humming- 

 birds. These are in the position of neutrals, free 

 to rano-e at will amidst the combatants, insulting 



