THE WATEK-OUZEL 289 



Were the flights of all the ouzels in the Sierra 

 traced on a chart, they would indicate the direction 

 of the flow of the entire system of ancient glaciers, 

 from about the period of the breaking up of the 

 ice-sheet until near the close of the glacial winter ; 

 because the streams which the ouzels so rigidly 

 follow are, with the unimportant exceptions of a 

 few side tributaries, all flowing in channels eroded 

 for them out of the solid flank of the range by the 

 vanished glaciers, the streams tracing the ancient 

 glaciers, the ouzels tracing the streams. Nor do we 

 find so complete compliance to glacial conditions in 

 the life of any other mountain bird, or animal of 

 any kind. Bears frequently accept the pathways 

 laid down by glaciers as the easiest to travel ; but 

 they often leave them and cross over from canon 

 to canon. So also, most of the birds trace the 

 moraines to some extent, because the forests are 

 growing on them. But they wander far, crossing 

 the canons from grove to grove, and draw exceed 

 ingly angular and complicated courses. 



The Ouzel's nest is one of the most extraordinary 

 pieces of bird architecture I ever saw, odd and 

 novel in design, perfectly fresh and beautiful, and 

 in every way worthy of the genius of the little 

 builder. It is about a foot in diameter, round and 

 bossy in outline, with a neatly arched opening 

 near the bottom, somewhat like an old-fashioned 

 brick oven, or Hottentot's hut. It is built almost 

 exclusively of green and yellow mosses, chiefly the 

 beautiful fronded hypnum that covers the rocks 

 and old drift-logs in the vicinity of waterfalls. 

 These are deftly interwoven, and felted together 



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