466 BULLETIN 17 6, UNITED STATES NATIONAL MUSEUM 



"Our four nests have been found at altitudes from 45 feet at Culia- 

 can, Sinaloa, to 1,450 feet at Guirocoba, Sonora. Specimens have 

 been collected at the highest elevations — Palo Verdes Mines, 4,900 

 feet; on the Urique River, Chihuahua, taken by myself, 5,000 feet; 

 and even on Mount Mohinora at nearly 10,000 feet — ^but no nests have 

 been secured at these altitudes. Although I observed both sexes re- 

 peatedly during May on Mohinora, feeding within a few feet of me 

 among the flowers in extraordinary mammoth beds of paintbrush, 

 they showed no indications of breeding." 



Courtship. — Mrs. Bailey (1928) refers to this briefly, as follows: 

 "The courtship 'pendulum swing back and forth in front of a 

 female,' when given by the Broad-bill, Mr. Willard says is 'higher 

 pitched than that of any of the other small hummers,' having 'the 

 zing of a rifle bullet' (MS.). It is of peculiar interest to hear from 

 Mr. O. W. Howard that while in Arizona he saw several of the male 

 Broad-bills in the vicinity of their completed nests." 



Nesting. — Mr. Moore's (MS.) remarks on nesting follow: "The 

 finding of my first nest at the Guirocoba Ranch, Sonora, was a wel- 

 come goad to a brain completely fagged by the terrific heat. The 

 tropical sun was desiccating a tiny arroyo with relentless power. 

 A female propelled its tiny atom of a body straight to a nest on 

 the branch of a small tree, overhanging the bank of the arroyo and 

 not 5 feet from the ground. It was an unusual demonstration of 

 courage and confidence in human beings, for the nest on May 2, 1934, 

 contained no eggs, being only half finished. I have known many 

 ruby-throated hummingbirds to desert an unfinished home, if one 

 climbed the nest tree, and never in my experience with some dozen 

 of them has a single male or female protected an eggless nest, as this 

 tiny parent did repeatedly during the next few days. 



""When it came to the more arduous operation of nest building, 

 involving the carrying of material and weaving instead of resting, 

 she preferred the cooler hours of the day from 3 : 30 until dark, and 

 did a prodigious amount of work. A red letter day of accomplish- 

 ment was May 2. At 5 : 30 p. m. the nest had attained one half 

 its final height, but at 9 o'clock the next morning the complete altitude 

 of the walls had been erected. As the nest, now before me, is approxi- 

 mately 1 inch high on the outside, the above statement means that 

 the bird built half an inch of wall material during the late afternoon 

 and early morning hours. In addition, she added the lining and 

 attached a considerable number of white cobweb strands, completely 

 swathing the bottom of the nest with them and supporting and con- 

 necting its outer rim to the leaves and tiny branchlets in the vicinity. 

 However, free access to the nest was not obstructed. 



"The most interesting nest-building technique was displayed a 

 number of times when I was within a few feet of the nest. The bird 



