TROCHILID^ — THE HUMMING-BIRDS. 443 



Mr. Salvin is of the opinion that Hiimming-Birds do not remain long- on 

 the wing at once, but rest frequently, choosing for that purpose a small dead 

 or leafless twig at the top, or just within the branches of the tree. While 

 in this position they trim their feathers and clean their bill, all the time 

 keeping up an incessant jerking of their wings and tail. 



In Mexico, where these birds are very abundant, they are attracted by the 

 blossoms of the Agave americana, and swarm around them like so many 

 beetles. As they fly, they skim over the fields, rifle the flowers, mingling 

 with the bees and the butterflies, and during the seasons of bloom, at cer- 

 tain hours of the day, the fields appear perfectly alive with them. The ear 

 receives unceasingly the whistling sounds of their flight, and their shrill 

 cries, resembling in their sharp accent the clash of weapons. Although the 

 Hiimming-Bird always migrates at the approach of cold weather, yet it is 

 often to be found at very considerable elevations. The traveller Bourcier 

 met with tliem on the crater of Pichincha, and M. Saussure obtained speci- 

 mens of Calothorax lucifcr in the Sierra de Cuernavaca, at the height of 

 more than 9,500 feet. 



While we must accept as a well-established fact that the Humming-Birds 

 feed on insects, demonstrated long since by naturalists, it is equally true 

 that they are very fond of the nectar of flowers, and tliat this, to a certain 

 extent, constitutes their nourishment. This is shown by the sustenance 

 which captive Humming-Birds receive from honey and otlier sweet sub- 

 stances, food to which a purely insectivorous ])ird could hardly adapt itself. 



Notwithstanding their diminutive size the Humming-Birds are notorious 

 for their aggressive disposition. They attack with great fury anything that 

 excites their animosity, and maintain constant warfare with whatever is 

 obnoxious to them, expressly the Sphinxes or Hawk-Moths. Whenever 

 one of these inoffensive moths, two or three times the size of a Humming- 

 Bird, chances to come too early into the garden and encounters one of these 

 birds, he must give way or meet with certain injury. At sight of the 

 insect the bird attacks it with his pointed beak with great fury. The 

 Sphinx, overcome in this unlooked-for attack, beats a retreat, but, soon 

 returning to the attractive flowers, is again and again assaulted by its infu- 

 riated enemy. Certain destruction awaits these insects if they do not 

 retire from the field before their delicate wings, lacerated in these attacks, 

 can no longer support them, and they fall to the ground to perish from other 

 enemies. 



In other things the Humming-Bird also shows itself all the more imperti- 

 nent and aggressive that it is small and weak. It takes offence at every- 

 thing that moves near it. It attacks birds much larger than itself, and 

 is rarely disturbed or molested by those it thus assails. All other birds 

 must make way. It is possible that in some of these attacks it may be in- 

 fluenced by an instinctive prompting of advantages to be gained, as in the 

 case of the spider, in whose nets they are liable to be entangled, and whose 



