232 BULLETIN 17 0, UNITED STATES NATIONAL MUSEUM 



descended, the Saw-whet shook its feathers, flew back and disappeared into the 

 cavity, reappearing in a moment to watch my movements. This was the usual 

 procedure during succeeding visits, except that it was sometimes necessary to rap 

 the stub lightly in order to bring the bird to its doorstep. The only note of pro- 

 test heard in the daytime was an occasional snapping of the mandibles. This 

 was more noticeable after the young were hatched. 



Rockwell and Blickensderfer (1921) describe a nest that was in an 

 unusual location in Colorado, quite in contrast with the usual location 

 in deep, shady, damp forests, or near water; they say: "The tree (a 

 large, dead yellow pine) in which this nest was located was on an ex- 

 posed slope commanding a wide view of the adjacent country. The 

 surrounding timber was sparse; the nesting cavity faced directly 

 south into the bright sunlight and was unshaded except for a single 

 overhanging dead branch; and the immediate surroundings were 

 very dry. The nearest stream was fully half a mile distant and there 

 was not even a trickle of spring water closer at hand." 



Eggs.— The saw-whet owl lays four to seven eggs, five or six being 

 the commonest numbers. The eggs are usually oval in shape, but 

 sometimes slightly ovate or more nearly globular. The shell is 

 smooth, with little or no gloss, and the color is pure white. The 

 measurements of 52 eggs average 29.9 by 25 millimeters; the eggs 

 showing the four extremes measure 31.5 by 25.2, 30 by 27, 28.3 by 

 25.4, and 28.9 by 23.6 millimeters. 



Young. — The period of incubation has been estimated as from 21 to 28 

 days; Mr. Terrill (1931) says "at least 26 days and probably longer." 

 Both sexes are said to assist in this, but probably most of it is done by 

 the female. The eggs are laid at intervals of from one to three days, 

 and, as incubation begins with the laying of the first egg, the young 

 hatch at variable intervals, and it sometimes happens that newly 

 hatched and nearly grown young are found in the same nest. 



Mr. Terrill says in his notes: "At birth the nestlings were blind 

 and helpless and very tiny, with a scanty covering of whitish down. At 

 the age of 8 to 9 days the ej^es were partly opened and the iris was a 

 dark inky color without lustre. When 16 to 17 days old, the upper 

 parts were a dark chocolate-brown. The development of the eyes was 

 very gradual, the yellow iris being first noted at this age, though the 

 yellow coloring was not so bright and clear as at the age of 19 to 21 

 days, and the lids were never fully opened. At the age of 26 to 28 

 days one of the owlets could fly about 15 feet from a log, but was 

 apparently unable to rise from the ground. The young left the nest 

 some time between July 17 and 22, when the oldest was from 27 to 

 34 days of age and could probably fly fairly well." 



Of the voice of the young, he says: "At the age of 4 to 6 days a 

 liquid peeping was practically identical with the peeping of baby 

 long-eared owls. Snapping of the mandibles was not noted until 

 after the sense of fear had been developed, at the age of 16 to 17 days. 



