RUFOUS HUMMINGBIRD 407 



different sound also. This sound is produced continually as long as the bird is 

 on the wing, and only varies by increasing in volume each time the bird moves 

 from its position in the air. The sound is difficult to describe, but might be 

 likened to tiny beads vibrating regularly in a thin metal bos. Although, as far 

 as my own observations go, the male rufous never flies without making this 

 vibrating sound, the female never at any time produces it. 



Mr. DiiBois says in his notes : "Usually the mother bird was silent ; 

 but when the nestling was two days old I once heard the mother 

 chirping for a moment, from among the branches of a fallen tree, 

 before she came to settle in the nest." When agitated she chirped 

 while on the nest. 



Field marhs. — The male rufous hummingbird can be easily recog- 

 nized by the large amount of rufous on the upper parts, including 

 the posterior portion of the crown, the back, and most of the tail; 

 the brilliant metallic scarlet gorget is very conspicuous and shines 

 like burnished gold in some lights; the chest is white, but otherwise 

 the underparts are pale rufous. The only species that closely 

 resembles it is Allen's hummingbird, which has a green back. 



The female can hardly be distinguished in the field from the female 

 of Allen's, as both have much light rufous on the underparts, and 

 their tails are largely rufous basally, the three outer rectrices being 

 broadly tipped with white. A close inspection of the tails will show 

 slight differences between the two species. The outer tail feathers 

 of the rufous are broader at the black space, about 0.15, as against 

 about 0.10 of an inch in Allen's. Ridgway (1911) says that in the 

 rufous "middle pair of rectrices metallic bronze-green (usually more 

 dusky terminally), both webs broadly edged basally with cinnamon- 

 rufous (sometimes with whole basal half or more of this color) ; next 

 pair with more than basal half cinnamon-rufous, then metallic 

 bronze-green, the terminal portion purplish black." And, of Allen's, 

 he says: "Middle pair of rectrices with basal half (laterally, at least) 

 cinnamon-rufous, the terminal half (more or less) metallic bronze- 

 green; next pair similar, but terminal portion (extensively) black, 

 the tip of inner web sometimes with a small spot of white." 



Enemies. — Mr. Sprot (1927) tells of a male rufous hummer that 

 tried its towering flight once too often, "when he staged a drop on 

 a Black Pigeon Hawk, and got caught." Probably other hawks, 

 and perhaps owls, have taken their toll. Mr. Skinner says in his 

 notes: "One was seen resting on a willow twig in the sun until an 

 irascible Audubon's warbler made a dive at it and drove it away, 

 but in a moment the hummer was back again. After its return, it 

 seemed very nervous, as if the rowdy Audubon had ruffled its feel- 

 ings. Another one was chased away by a lutescent warbler." 



Mr. DuBois (1938) saw a large black and yellow fly attack the 



