STATUS AND DISTRIBUTION 261 



I had earlier shared Bishop's opinion, formed as he traveled west- 

 ward along the Yukon River that the number of species of American 

 land birds gradually diminished westward in Alaska. But compari- 

 son of the avifauna of Old Crow, Anaktuvuk, and Kobuk shows the 

 decrease to be marked only in the family of flycatchers {Tyrannidae) , 

 none of which have been reported at Kobuk. Swainson's thrush 

 {Hylocichla ustulata incana) has not yet been identified at Kobuk, but 

 I think that it occurs there. Otherwise the swallows (Hirundinidae) , 

 thrushes (Turdidae), and even the small wood warblers (Parulidae) 

 populate the arctic woodland thickly from Old Crow to Kobuk and 

 some species of thrushes and wood warblers commonly nest on the 

 tundra. 



