20 U. S. NATIONAL MUSEUM BULLETIN 217 



and rock ptarmigan to feed upon. The branches and twigs of the 

 willows protruding through the snow are exposed during most of 

 the winter. Since the larger arctic animals and birds are not bothered 

 by winter cold (Scholander, Hock, Walters, Johnson, L. Irving, 1950 ; 

 L. Irving, 1951), the exposure of their sources of food gives a certain 

 advantage to tundra residents over those in the windless forest areas 

 where snow and frost cover the branches as well as the ground. 



The lakes are not usually iced over until late in September, but by 

 early October the ice may be a foot thick. On any extensive ice sur- 

 faces the snow may be blown into hard drifts with extensive clear 

 areas, so that the frequent winds facilitate winter travel for men and 

 animals. Thus, if properly considered and utilized, the tempestuous 

 winter weather in the mountains facilitates the feeding of animals 

 and the travel of man. And, in fact, the variety of human artifacts 

 found widely distributed in Anaktuvuk and Killik Valleys (W. 

 Irving, 1951, 1953), shows that people using Mesolithic implements 

 once inhabited these valleys. 



In late May the winter snow has generally melted or evaporated 

 and the streams and rivers have broken through to flood over the 

 ice which still remains fixed to the bottom. In some lakes the ice 

 may remain sufficiently firm for landing light aircraft until after 

 June 10, although the margins of many lakes are open sufficiently 

 for the feeding of shore birds and ducks after the middle of May. 

 Fresh snowfalls and cold freezing weather occurred in the first week 

 of June in 1948 and 1949, and in 1949 another period of several days 

 followed, around June 20, when the ground was covered with 6 inches 

 of fresh snow. These June snow storms obviously harassed the shore 

 birds, for they then had no place to feed or land except upon a few 

 rocks protuding above the stream beds. The distress of the expressive 

 yellowlegs and tattlers was pathetic to watch. Many nests were cov- 

 ered and the eggs destroyed by the snow ; and yet a few days after the 

 return of warm weather the exuberance of bird life in Arctic spring- 

 time reappeared. In spite of these recurring hazards, the bird popu- 

 lations flourish as a whole, and the occasional hardships are appar- 

 ently offset by generally favorable conditions. It seems that these 

 populations migrating to the arctic encounter an average condition 

 of abundant food and favorable weather and only individuals suffer 

 from the vicissitudes of climate. 



After mid-June, freezing temperatures are rare, rain is uncom- 

 mon, and long sequences follow of brilliantly clear days with most 

 agreeable temperatures. Daylight is continuous and during warm 

 parts of the long days children play as noisily in the river as they do 

 in any climate. The well drained areas of the tundra and the mountain 

 slopes rapidly dry to a desert appearance. 



