DIPPER 545 



and it always forms a ready aid in identifying the species. The rock and 

 canon wrens have a similar movement; but the purpose of this dipping 

 in any of these birds is not known. One dipper seen standing on the 

 margin of the ice in the river in Yosemite Valley, December 22 (1914), 

 was bobbing upon one leg; the other leg was presumably drawn up into 

 its plumage. 



The dipper forages along the shore, on rocks in the stream (pi. 52), 

 and on the bottom of the stream beneath the running water. When hunt- 

 ing along the shore the bird moves by short hops, turning to one side 

 and the other, and bobbing its hinder parts almost incessantly. If the 

 shore line be interrupted by a small embayment of quieter water the bird 

 may swim across on the surface, or it may fly, holding its feet stretched 

 forward and downward in readiness to alight when a suitable rock appears 

 or the shore is again reached. "When getting food beneath the surface, the 

 dipper dives directly into the stream, usually against the current, and then 

 seemingly walks along the bottom, the wings assisting. As it walks along 

 it searches the crevices between rocks and the submerged surfaces of 

 boulders where are to be found the larvae of certain insects which it seizes 

 and devours. Near El Portal, one day in December, a dipper was seen 

 to plunge head first into the rushing Merced River, to reappear about 

 twenty seconds later some fifteen feet up the stream. Upon emerging, a 

 shrug or two of the body rid the plumage of most of the adhering water. 

 In summer, after the young leave the nest and before they are able to 

 live independently, they perch on rocks along the shore while the parents 

 hunt and dive in search of food for them. 



The song of the American Dipper is given throughout most of the year, 

 perhaps more frequently during the winter time than in summer. We 

 have heard it many times in the fall and winter months at El Portal and 

 in Yosemite Valley. Certainly it comes more often to attention in these 

 seasons when most other birds are quiet and when the rush of the rivers 

 and booming of the Valley falls are stilled. On December 22, 1914, several 

 of the birds were playing about the river ice in Yosemite Valley and 

 giving voice to numerous calls; on March 1, 1916, while snow was falling 

 heavily in the Valley, a dipper was heard in full song. 



The utterance is not easily transcribed, being varied as to both theme 

 and rendering. Some passages suggest comparison with notes of the 

 California Thrasher, some with those of the mockingbird, and others with 

 certain wren notes; but there is a distinctive quality to the dipper's song 

 which makes direct comparison misleading. Perhaps part of the im- 

 pressiveness of the song comes from the surroundings amid which it is 

 heard, but certain of its pleasurable features are assuredly intrinsic. 



