262 



Sierra Club Bulletin. 



Tuolumne. The abdomen and shorter under tail-coverts 

 of both male and female are white in summer. This fact, 

 together with the intenser blue coloring, the absence of 

 rufous and brown on the breast, and the somewhat larger 

 size, serves to distinguish the Mountain Bluebird from 

 the Western Bluebird (Sialia mexicana occidentalis) , into 

 whose range the habitat of the former sometimes extends. 

 The sight of one of these bluebirds, in full summer 

 plumage, hovering a few feet above the flowery carpet 

 of a meadow, v/hile hunting for grasshoppers, makes a 

 memorable occasion. 



On the 28th of July, 191 1, the Sierra Club made a side 

 trip from Kerrick Canon to Tilden Lake. On the way 

 thither I observed that Mountain Bluebirds were numer- 

 ous along the trail. The following day I tried to locate 

 nests in the neighborhood of our camp at the lower end 

 of Tilden Lake. In a short time I found the homes of 

 three pairs of these gentle mountaineers. All of them 

 had appropriated abandoned woodpecker holes, excavated 

 in dead or dying tamarack pines (P. murrayana). The 

 altitude was 9,000 feet. 



One of these nesting sites was in a large dead pine at 

 the lower end of the lake. The opening was a consider- 

 able distance from the ground. The young must have 

 been fairly large, for they chirped loudly during the 

 feeding operations. I photographed the tree and its back- 

 ground, as shown in the accompanying cut. It affords a 

 glimpse of what is in many ways a characteristic summer 

 environment of the Mountain Bluebird in the Sierra 

 Nevada: an open forest consisting almost entirely of 

 Murray pines ; an overflowed meadow in which the Blue- 

 birds were foraging together with Clarke Nutcrackers 

 (Nucifraga columhiana) ; patches of snow lingering in 

 hollows and on the ridges. 



The second nest was about thirty feet above the ground 

 in a dead pine overhanging the stream that carries off 

 the surplus waters of Tilden Lake. The third was hardly 

 more than fifteen feet from the ground. The birds had 



