536 ANIMAL LIFE IN THE 10 SEMITE 



12 inches above the ground. During the season of 1915, 3 nests of this 

 species, all located on the floor of Yosemite Vallej', came under more or 

 less continued observation. 



The first of these was found June 10 (Mrs. Joseph Grinnell, MS). It 

 was 12 inches above the ground in a thimbleberry bush in a thicket near 

 a stream. The structure was made of pine needles and grass blades and 

 stems, and was lined with fine round grasses and black horsehair. On this 

 date there was in it a single egg, about the size of that of a Western 

 Chipping Sparrow, creamy white with brown splotches around the larger 

 end. Two days later the nest held three eggs, showing that one had been 

 deposited each day. The set was increased to four, presumably, on the 

 day following, although the place was not visited again until June 17. 

 On none of these visits was either of the parents seen. Identification of 

 the nest was only made at a later date when one of the adults was sur- 

 prised there. When seen on June 24 (pi. 51h) the eggs seemed nearly 

 ready to hatch and this surmise was confirmed the following day, June 25, 

 when four naked pinkish yellow nestlings were found entirely out of their 

 shells. Assuming that the fourth egg was laid on June 13, and that the 

 parent bird began incubation immediately thereafter, the period of incu- 

 bation in this case was 13 days. On June 26 the yoiing birds showed dark 

 gray down which looked purple when the sunlight touched it. On June 28 

 the young in this nest had disappeared and since, when last seen, they 

 were entirely too small to leave voluntarily, some prowling enemy must 

 be held to account for their early disappearance. 



Another nest, found on June 13, 1915, has been described by Miss 

 Margaret W. Wythe (1916, pp. 123-127). It was discovered soon after 

 the eggs were laid and was watched until the young had left. The nest 

 rim was 9 inches above the ground, the outside diameter and height each 

 3^ inches, the cavity 21/^ inches across and II/2 inches deep. It was placed 

 between four stems of chokecherry, and in construction was similar to 

 the one previously described. 



The female alone brooded, sitting very close some days, but being 

 absent continuously for fully twenty minutes on the 18th. Two eggs 

 hatched on June 23 and another by the following morning. The fourth 

 proved infertile. The two young that hatched on the 23d grew appreciably 

 in one day, and on the 24th were about 2 inches in length and the same 

 in stretch of wings. The down was conspicuous on these two on the second 

 day. The female brooded at intervals. An hour's observation at close 

 range on June 27 disclosed the fact that the female came to the nest 

 every 3 to 5 minutes, while the male visited the place but once during the 

 period specified. The three young were now about of equal size and juvenal 

 feathers had appeared on the head, back, and wings. The eyes of one bird 

 were open on this date and those of another the day following. 



