GOATSUCKERS, HUMMING-BIRDS, ETC. 249 



found in large numbers, for it is the most common of all the 

 species that frequent the mountains. It seeks its food of 

 insects and honey from the flowers of a prolific flora extend- 

 ing from Wyoming and Idaho southward through Colorado, 

 New Mexico, Arizona, Texas, and over the table lands of 

 Mexico into Guatemala. It is pretty generally distributed 

 throughout the various mountain systems between the east- 

 ern slopes of the Rocky Mountains and the Sierra Nevadas. 



The broad-tails are very abundant in the balsam and 

 pine belts of the San Francisco Mountains of Arizona, 

 where their principal food plants are the scarlet trumpet 

 flower and the large blue larkspur. 



It seems strange and unnatural that so delicate a bird 

 and one so highly colored should frequent localities where 

 periods of low temperatures are common. Yet the broad- 

 tailed humming-bird prefers high elevations and has been 

 known to nest at an altitude of eleven thousand feet, and 

 it seldom breeds at places lower than five thousand feet. 



The males leave for their winter home very early in the 

 season. Usually this migration takes place very soon after 

 the young birds leave their nests. Mr. Henshaw attributes 

 this movement of the males to the fact that their favorite 

 food plant, the Scrophularia, begins to lose its blossoms at 

 this time. He says: "It seems evident that the moment 

 its progeny is on the wing and its home ties severed, warned 

 of the approach of fall alike by the frosty nights and the 

 decreasing supply of food, off go the males to their inviting 

 winter haunts, to be followed, not long after, by the females 

 and young. The latter, probably because they have less 

 strength, linger last." 



