MAMMALS AM) BIRDS OF ALASKA 



3 



longest river in North Amcricji, already 800 miles from its source in 

 Yukon Territory when it reaches the boundary, meanders an addi- 

 tional 1,500 miles throuo^h Alaska before pouring its silt-laden, gray 

 ilood into Bering Sea, where together with the Kuskokwim, it forms 

 a vast delta more than 10,000 square miles in extent that furnishes 

 one of the most ideal spots on the continent for nesting waterfowl. 



The Arctic Plains Region, of actual arctic conditions, constitutes 

 about on(>-sixtli of the Territory. Its low, rolling hills and plateaus 

 are diss(»cted by northward-flowing rivers and streams. Its climate 

 is cold and arid, with only about 6 to 8 inches of precipitation. The 

 winters are long, chirk, and bitter cold and the summers short and 



Figure 2. 



Mount McKinley, Alaska, altitude 20,300 feet, the highest peak in 

 North America. (Photo by Ira N. Gabrielson.) 



cool. Even so, the period of continuous sunshine, extending from 

 May until August, induces a luxuriant growth of mosses, bright 

 flowers, lichens, and grasses, though the soil cover thaws only to a 

 depth of about a foot. Timber is thin or wanting, and willows, some 

 of them only a few inches high, become the predominant tree growth 

 in the Arctic drainage. 



The Aleutian Islands Region extends westward from the tip of 

 Alaska Peninsula for 1,100 miles in a long arc that places the outer- 

 most island of Attu within 600 miles of Kamchatka and the Japanese- 

 owned Kurile Islands. The Aleutians may be described as treeless, 



