BUBY-CBOWNED KINGLET 593 



A nest of the Ruby-crowned Kinglet was seen in an incense cedar close 

 by the Sentinel Hotel Annex in Yosemite Valley in late May, 1903 (Wid- 

 mann, 1904, p. 67). 



Western Gnatcatcher. Polioptila caerulea obscura Ridgway 



Field characters. — Size small, near that of Kinglet but form slenderer; length about 

 414 inches; tail long, equal to body; bill slender, nearly as long as head. Top of 

 head and back bluish gi'ay; tail black centrally, with easily seen margin of white; under 

 surface of body plain grayish white. Males have a narrow black band across forehead. 

 Flight wavering, seemingly indecisive; when perched, tail is persistently 'wig-wagged.' 

 Voice: Weak; a series of high-pitched wheezy notes, zeu, see, sree, or cheu, chee, chree, 

 three to six of such notes in a series; call notes of both sexes a flat chee-y, of similar 

 quality. 



Occurrence. — Common summer visitant throughout Upper Sonoran Zone on west slope 

 of Sierra Nevada. Observed at Lagrange and Pleasant Valley and thence east to El 

 Portal and to 6 miles east of Coulterville. Small numbers wander to higher zones after 

 the nesting season; for instance, noted by us at 6300 feet altitude near Glacier Point, 

 August 17, 1915, and at 10,300 feet on ridge near Fletcher Creek, September 4, 1915. 

 Eecorded in Yosemite Valley August 22 to September 10, 1920 (C. W. Michael, MS), 

 and on September 25, 1917 (Mailliard, 1918, p. 19). Seen once east of the Sierras, at 

 Williams Butte, September 21, 1915. Forages and nests chiefly in blue oaks, but also 

 in digger pines and greasewood brush. In pairs or family parties, but never in larger 

 assemblages as in the case of the Bush-tit. 



The Western Gnatcatcher is a very small bird, of active temperament, 

 which, by habits as well as structure, betrays relationship with the verj'' 

 differently colored kinglets. But instead of living in the mountain conifer- 

 ous forests inhabited by the latter birds, the gnatcatcher, during the sum- 

 mer season, lives in the warm dry foothills which intervene between the 

 heated San Joaquin Valley and the cooler upper altitudes of the mountains. 

 The traveler who enters the Yosemite region along any of the roads from 

 the west, upon arriving at the frontier outposts of blue oaks which are 

 scattered over the first of the foothills far in advance of the digger pines 

 and chaparral, will almost immediately be apprized of the gnatcatcher 's 

 presence there by hearing the fine wheezy notes of the bird. From these 

 outlying foothill oaks on to the margin of the yellow pine belt, at the lower 

 edge of the Transition Zone, the gnatcatcher is, during the summer months, 

 one of the most abundant of birds. 



The Western Gnatcatcher is migratory in the Yosemite region, arriving 

 in numbers probably in April and departing in late fall. It was already 

 present at El Portal on April 27 (1916). By early ]\Iay the birds are 

 busy with nesting duties, and as early as May 30 (1915) young have been 

 noted out of the nest. After the breeding season, a few gnatcatchers 

 wander up into the higher zones, as instanced above, but the bulk of the 

 population remains in the foothills until the time of departure in the fall. 



