Vol. XXXVII 



1919 



Blackwelder, Birds of the Upper Yukon. 57 



NOTES ON THE SUMMER BIRDS OF THE UPPER 

 YUKON REGION, ALASKA. 



BY ELIOT BLACKWELDER. 



In the summer of 1915 I made a journey to that part of eastern 

 Alaska lying south and southwest of the Yukon River, and north- 

 east of the Tanana. Although the object of the trip was geological, 

 the birds were given such attention as opportunity permitted. 

 Not being properly equipped for collecting specimens, my chief 

 reliance for identification was a ten power Terlux binocular glass. 

 The route traversed was along the Yukon River from White Horse 

 in Yukon territory to Circle, thence westward across the moun- 

 tains to the White Mountain range near the head of Beaver Creek. 

 We descended Beaver Creek to the Yukon Flats and emerged upon 

 the Yukon itself near Beaver village — about seventy miles below 

 Ft . Yukon. From that point we returned up the river as we came. 



The region has been sufficiently described by previous explorers,' 

 and especially by members of the U. S. Geological Survey. In 

 addition, ornithological investigations have been made along the 

 Yukon. No ornithologist, however, has visited the remote White 

 Mountains. 



Most of the region is mountainous, but the relief is less than 

 3000 feet, and the highest peaks but little over 5000. Along the 

 rivers there are some spacious basins. Of these the largest is the 

 so-called Yukon Flats between Circle and old Fort Hamlin, an 

 area of more than 7000 square miles. 



Timber-line is about 2500 feet above sea level, but varies accord- 

 ing to the direction of the slope, the nature of the soil and some 



1 Dawson, G. M., Explorations in Yukon and northern British Columbia; Geol. Survey 

 of Canada Bept. for 1887-1888. Report B. 



Prindle, L. M., A geological reconnaissance of the Fairbanks Quadrangle, Alaska: 

 U. S. Geol. Survey Bull. 525, 1913. 



Bussell, I. C, Notes on the surface geology of Alaska: Bull. G. S. A. Vol. 1, 1890, 

 pp. 72-99; 154-155. 



Spurr, J. E., Geology of the Yukon gold district, Alaska: U. S. Geol. Survey Ann. 

 Bept. 18, pt. 3, pp. 87-392, 1897. 



