280 BULLETIN 196, UNITED STATES NATIONAL MUSEUM 



state, not regurgitated. Crickets, grasshoppers, beetles, butterflies, and worms 

 are their menu, with a few berries. The young Bluebirds double in weight every 

 twenty-four hours for the first week, and in twelve days are growing a respectable 

 crop of feathers, though the bare skins is still distressingly visible. Their breasts 

 gradually take on the soft, mottled light and dark, and the upper parts have a 

 hint of blue among the grayish brown on the wings and tail. One would suppose 

 that this blue on the upper parts would be too conspicuous, but when the young- 

 sters leave the nest and perch on the soft gray of the dead trees, they become 

 almost invisible in the strong sunlight. 



On Mount Rainier, on July 18, Taylor and Shaw (1927) discovered 

 a nest of the mountain bluebird 30 feet up in a dead stub, and watched 

 the parents feed the young for over half an hour and summarized their 

 observations as follows: 



The young were fed 14 times in 34 minutes, the feedings averaging 2.4 minutes 

 apart. The male fed twice in this time, the female 12 times. The rate of feed- 

 ing established by this set of observations is approximately 22 times an hour. 

 If this is maintained for five hours in the morning and another five hours in the 

 afternoon, 220 feedings a day would be indicated. But on Mount Rainier at this 

 time of year there were nearly 17 hours of daylight. If the birds averaged 22 

 feedings an hour for 17 hours, a total of 374 would be indicated. This figure 

 may be closer to the truth than the former one. The male was a shy bird and 

 usually paused on a short branch one to three or four minutes, afraid to go to 

 the nest while the observer was about. The mother was far less cautious. She 

 usually perched for a moment on a branch near the nest and then went directly 

 to it, often entering the cavity and apparently covering the young for a moment. 



Probably throughout most of its range the mountain bluebird rears 

 two broods in a season, or tries to do so, perhaps sometimes three; but 

 in the northern portion of its range and on the higher mountains, 

 where the nesting dates seem to be later, it may have time for only one. 



Plumages. — Ridgway (1907) describes the young male in juvenal 

 plumage, as follows: 



Pileum, hindneck, back, and scapulars light brownish gray or drab-gray the 

 interscapular area usually more or less streaked with white; rump and upper 

 tail-coverts light ash gray; remiges and rectrices as in adults, but with distinct 

 terminal margins of white (duller on remiges), the tertials dusky gray with pale 

 gray or dull whitish margins; middle wing-coverts brownish gray margined 

 terminally with dull white or brownish white; greater-coverts dull blue, margined 

 terminally and edged with pale gray or whitish; a conspicuous orbital ring of 

 white; lores grayish white, suffused with dusky in front of eye, and margined above 

 by dusky; auricular region brownish gray or pale brownish gray, indistinctly 

 streaked with paler; throat and upper chest pale gray (passing into dull white on 

 chin), indistinctly streaked with whitish; chest, sides, and flanks squamately 

 streaked (broadly) with grayish brown or drab, the center of the feathers being 

 white; rest of under parts white. 



He says of the young female: "Similar to the young male, but blue 

 of wings and tail much duller and (especially that of wings) greener; 

 color of back, etc., browner." 



The postjuvenal molt begins early in August, or earlier, the date 



