624 ANIMAL LIFE IX THE YOSEMITE 



chicken feathers from the nearby farmyard. The dimensions outside were 

 roughly 6 or 7 inches in diameter and 2i/^ inches in height. The depression 

 for receiving the eggs was 314 inches wide and ly^ inches deep. After 

 one brood had been reared this nest was re-lined to receive a second set 

 of eggs. 



In 1916, nesting activities with the Mountain Bluebirds (pi. 566) in 

 the neighborhood of Mono Lake were instituted early in May, which makes 

 it readily possible for some at least of the pairs there to rear two broods. 

 Thus the pair observed at Mono Lake Post Office had on May 20, 1916, a 

 nest with 6 fresh eggs. The 5 young reared from this lot were abroad 

 and being cared for by the male on June 30, and by July 3 there was a 

 second set of 5 eggs which the female had commenced to incubate. A pair 

 of birds which arrived at the Farrington ranch about May 1 took possession 

 of an old Flicker hole almost at once. By May 10 the nest lining had been 

 finished and by May 16, 5 eggs had been laid ;. incubation commenced the 

 next day. 



The several Mountain Bluebirds encountered on Mount Hoffmann on 

 June 29 and 30, 1915, fluttered about as though anxioiLS over the security 

 of nests. They probably had eggs or small young in cavities left by the 

 rotting out of branches in the stunted white-barked pines which abounded 

 on the upper slopes of the peak. When we reached Tuolumne Meadows 

 early in July of 1915 the bluebirds were already well started on their 

 nesting program, as by July 8 one nest there had 3 young nearly ready 

 to fly and other pairs were busily engaged in getting food for young. 

 Presumably these high-mountain birds are one-brooded, for we did not 

 see young abroad until well along in July and there would not have been 

 time for them to rear another brood that season. 



When the eggs have hatched both parents attend to feeding the young, 

 and if a person approaches a nest at this season the bluebirds will hover 

 in the air before the site and utter remonstrant chirps. After the broods 

 were out, the relative numbers of the species almost reached the status 

 of 'abundant.' The young Mountain Bluebirds have a spotted pattern 

 of markings in the juvenile plumage — a ' family ' resemblance to the robins, 

 thrushes, and solitaires. In the bluebird this is due to white center streaks 

 on the feathers of the breast and back. This plumage is worn but a short 

 time, being replaced in early fall by one which is practically identical with 

 that of the adults. 



In the nesting season and indeed through most of the year the Mountain 

 Bluebird subsists upon insects. These are captured in two totally different 

 ways, according to the habits of the insects sought. For beetles and others 

 which fly through the air a bluebird will take position on a boulder in a 

 meadow or on the low outswaying branch of some tree and dart after the 



