442 BULLETIN 17 0, UNITED STATES NATIONAL MUSEUM 



eggs showing the four extremes measure 29.9 by 25, 26 by 22.3, and 

 25.9 by 22 millimeters. 



Young. — Major Bendire (1892) says: "One of the parents is always 

 at home after the first egg is laid, and frequently both. The male 

 assists in incubation, which lasts about two weeks." Nothing seems 

 to be known about the care of the young, their development, or their 

 habits, except that they are attended and fed by their parents for 

 some time after they leave the nest. 



Plumages. — I have seen only one downy young of the elf owl; it 

 was well covered with pure-white down; they are said to be about as 

 big as a man's thumbnail, when first hatched. 



In the juvenal plumage the upper parts generally are "drab", more 

 grayish on the pileum; the pileum is nearly, or quite, immaculate, 

 the back is finely and inconspicuously barred with dusky and "ochra- 

 ceous-tawny", the under parts are grayish white, heavily mottled, 

 spotted, or finely barred with dusky, and without any, or very little, 

 pale buff or brown; the tawny and white face pattern of the adult is 

 only faintly indicated, and there is no buff on the throat; the wings 

 and tail are as in the adult. This plumage seems to be worn for 

 only a short time, as a more or less complete body molt produces, 

 during June and July, a plumage that is practically adult. The 

 complete, annual molt of adults seems to take place in September and 

 October. Ridgway (1914) recognizes two color phases, the commoner, 

 gravish phase, and a browner phase. 



Food. — The food of the tiny elf owl seems to consist almost entirely 

 of various insects and their larvae, such as crickets, grasshoppers, 

 beetles, caterpillars, centipedes, and other small fry. Two that Mr. 

 Gilman (1909) had in captivity "freely ate what few crickets and 

 grasshoppers I could secure for them, but refused to eat small birds." 

 Mr. Campbell (1934) found in the stomachs of two of these owls five large 

 bot fly pupae, one Hemiptera, and one vinegarroon. Apparently this 

 little owl is not so savage and aggressive as the pygmy owls, and it does 

 not often attack birds, though feathers have been found in its stomach. 



Behavior. — The elf owl is decidedly nocturnal in its habits, remaining 

 concealed during the daytime in some convenient hole, or, more 

 frequently, in some dense thicket or under cover of thick foliage, 

 where it sits motionless and is not easily discovered. I have been 

 told that it does not live in the holes in the saguaros except in the 

 nesting season, but we know very little about its habits at other seasons. 

 In the evening twilight these owls become very active, and may be seen 

 flying about, or may be easily located by their peculiar notes. They 

 are sometimes seen flying about the campfire, probably chasing the 

 insects that have been attracted by the light. William Brewster 

 (1883) quotes the following from field notes of Frank Stephens: 



I was walking past an elder bush in a thicket when a small bird started out. 

 Thinking it had flown from its nest I stopped and began examining the bush, when 



