518 ANIMAL LIFE IN THE YO SEMITE 



The forage range of this warbler lies chiefly in trees other than conifers. 

 Such trees as the black oak and big-leafed maple renew their foliage every 

 spring and the Calaveras Warblers find excellent forage in the insects and 

 larvae which feed upon this tender new leafage during the spring and 

 summer months. Less often these birds may be found in golden oaks 

 and occasionally in Douglas spruces. They usually forage 25 to 40 feet 

 above the ground, keeping within the stratum of new foliage, but they 

 have been seen as low as 10 feet and as high as 70 feet above the earth. 

 When within the foliage their yellow and green coloration makes it difficult 

 to locate them, especially as the birds do not move about as rapidly as 

 some of the other warblers. At times a Calaveras Warbler will poise on 

 rapidlj^ beating wings to capture some insect otherwise out of reach. 



A good view of the male Calaveras Warbler reveals a plainly colored 

 bird, lacking contrasted markings of any sort. (See pi. 9a.) The head 

 is clear gray, the throat and lower surface continuously clear yellow, the 

 upper surface olive green. The female differs only in showing less contrast 

 between the dull gray of the head and the olive green of the back. There 

 is lacking in both sexes the brilliant yellow of the Yellow and Pileolated 

 warblers, and there are none of the black and white markings of the 

 Audubon, Hermit, and Black-throated Gray warblers. The Calaveras 

 Warbler bears somewhat of a resemblance to the Tolmie, especially in the 

 immature plumage, but then the difference in habitat and the smaller size 

 of the former are sufficient for distinguishing the two. 



A nest of the Calaveras Warbler was discovered in Yosemite Valley 

 near the base of Sentinel Rock on May 26, 1911. The location was only 

 about 75 feet from the much traveled south road on the Valley floor and 

 at the base of the talus pile of huge boulders. The nest was on the face 

 of one of the larger of these boulders, partly in a diagonal fissure. It 

 was on the north side of the rock and so never received any direct rays 

 of sunlight. The whole face of the boulder was covered densely with 

 yellow-green moss which in places was overlaid by olive-gray lichens. The 

 nest was 43 inches from the base of the rock and about 60 inches from the 

 top. The whole vicinity was densely shaded by black oaks and firs and 

 the ground beneath was strewn with dead last year's leaves of the oaks. 

 There were 5 eggs, and incubation was far advanced. When the nest was 

 first discovered, the parent birds acted very shyly, but after a while they 

 began to show much anxiety, coming down as close as 10 feet from the 

 observer who was sitting below the nest. The female was the bolder of 

 the two birds. Their excited tsits attracted other birds for a time, among 

 these being a brilliant male Hermit Warbler, a singing male Golden- 

 crowned Kinglet, and some Ruby-crowned Kinglets and Western Warbling 

 Vireos. 



