546 ANIMAL LIFE IN THE YOSEMITE 



The call note is short and rather burred, uttered singly when the dipper 

 is 'jouncing' on a rock, or given in rapid series when the bird takes to 

 flight. One of our renderings of it is zit, zit, zit, . . . ; another hzeet, or 

 extended to hz-ze-ze-ze-ze-ze-et. It is quite different in character from the 

 song, and resembles in general character the call note of the canon wren. 



The American Dipper nests amid the surroundings which harbor it 

 throughout the year, placing the structure on a rock close to or over 

 rushing water where the surface of the nest will be kept wet by spray. 

 Interiorly the nest is much like that of a canon wren, but its outer walls 

 consist of moss which, being continually moistened, remains green through- 

 out the period of occupancy. The entrance is at the side, so that the whole 

 structure is oven-like. Occasionally the nest is placed under a waterfall 

 and only comes to view upon the cessation of the flow in the autumn. 

 In former years a pair of dippers nested on the stone abutments to the 

 old bridge near the Sentinel Hotel, but replacement of the structure by a 

 new one of modern type, with smooth-finished surfaces, left no place for 

 the birds; in 1919 no dippers were to be found in that vicinity. 



On May 10 (1916) a nest containing five birds about five days old was 

 seen on a beam under the bridge over Rush Creek, southeast of "Williams 

 Butte. A two-thirds grown youngster was being fed by an adult on May 26 

 (1911), in Yosemite Valley near the Sentinel Hotel. A young dipper 

 already able to live independently was seen on Indian Caiion creek in 

 Yosemite Valley on July 6 (1915). These dates indicate a nesting season 

 continuing at least from April until the end of June. 



In winter months dippers appear on the Merced River below El Portal 

 and then range westward at least to Goff. They are to be seen readily from 

 passing trains. Whether these are birds forced down from the ice-bound 

 streams of the high Sierras or are migrants from farther north is not 

 known. 



Sage Thrasher. Oreoscoptes montanus (Townsend) 



Field characters. — Size nearly that of Eobin; build more slender. Under surface 

 of body dull white marked with coarse streaks of brown; upper surface plain grayish 

 brown; tail tipped with white. Voice: Song a series of clear warbling notes of varying 

 pitch, well sustained to the end. 



Occurrence. — Common summer visitant east of Sierra Nevada, from near Silver Lake 

 eastward. Eecorded once (April 20, 1919) as a transient on west slope at Smith Creek, 

 east of Coulterville. Keeps close to ground; lives in sagebrush during summer season. 

 Solitary or in pairs. 



The Sage Thrasher is to be found in the true sagebrush (Artemisia 

 tridentata) which abounds on the flats and gentler slopes east of the main 

 Sierra Nevada. The bird's spotted under surface and plain back both 

 match in color tone the prevailing gray of its environment. 



