146 



NATURALIST'S GUIDE TO THE AMERICAS 



tions, this method is preferred for con- 

 venience, economy and speed. 



4. Arctic coast region 



A. Topography. This is the treeless 

 coast region of northern and western 

 Alaska, including the Alaska Peninsula 

 and the Aleutian Islands which, at least 

 biologically, belong with it. For practi- 

 cal purposes, it may be denned on the 

 east and south by the irregular line 

 formed by the extreme limit of tree 

 growth, but its general conditions ex- 

 tend, with interruptions, throughout 

 much of the interior region in the ele- 

 vated areas above timber and in scat- 

 tered parts of the interior lowlands 

 which, for local reasons, are without 

 trees. It is flat or slightly rolling 

 ground, including the deltas of the 

 Yukon, Kuskokwim, Kobuk and some 

 other rivers of fair size. Elsewhere it 

 is traversed by small meandering 

 streams and dotted with lagoons and 

 small ponds. Its average width is 

 scarcely more than 100 mi., but in the 

 north it is continuous with treeless 

 mountains which lie between it and the 

 timbered interior. The Alaska Penin- 

 sula and Aleutian Islands consist largely 

 of volcanic mountains. 



B. Climate. From the Arctic coast 

 at Point Barrow to the Aleutian Islands, 

 there is considerable range in climatic 

 conditions. The Arctic coast proper is 

 not so warm in summer and not so cold 

 in winter as the interior forested region. 

 The maximum for July and August is 

 about 65 and the minimum for January 

 and February is about 55. Neverthe- 

 less, nearly every month in the year may 

 be subject to light frost, and in early 

 June or late August frost is usual. 

 Temperatures on the coast of Bering 

 Sea average somewhat higher, and on 

 the Alaska Peninsula and the Aleutian 

 Islands they never go to extremes. 

 Nevertheless, the means for the four 

 warmest months, effective in controlling 



the distribution of life, are substantially 

 the same at Unalaska in the Aleutian 

 Islands and at St. Michael on the cen- 

 tral coast of Bering Sea. 



The precipitation on the Arctic coast 

 is the least of any part of Alaska, averag- 

 ing only 6 to 8 in. per annum, almost 

 comparable to that of a desert region. 

 The Bering Sea coast has more, 20 to 30 

 in., and the Aleutian Islands still more, 

 perhaps 80 in., and more rainy daj^s 

 (250) than any other part of the terri- 

 tory. 



C. Biota. Vegetation: Although en- 

 tirely non-arborescent and including 

 relatively few species, the vegetation is 

 profuse. It forms a thick continuous 

 mat over the surface of the ground, in- 

 cluding depauperate willows, Vaccinium, 

 Cassiope, Ledum, Arctos, Dryas, and 

 Empetrum. With these are mixed a few 

 grasses and sedges and various mosses 

 and lichens. There are many saxifrages 

 and bright flowered poppies and butter- 

 cups. 



Animals: The animals are strictly 

 Arctic types. Mammals include the 

 Arctic fox, wolverine, weasel, polar 

 bear, barren-ground caribou, lemming, 

 Arctic hare, walrus, and various seals. 

 The birds comprise many migrating 

 shorebirds, ducks and geese, including 

 the eider ducks. Ptarmigan are gen- 

 erally distributed, and small land birds 

 are reduced to few species, as snow 

 bunting, redpolls, and longspurs. The 

 invertebrate marine fauna is Arctic in 

 character, but quite varied and em- 

 braces at least 200 species. 



D. Travel conditions. Regular steamers 

 during the summer season from June to 

 September run to Unalaska and Nome. 

 Yukon River steamers also come to the 

 coast at St. Michael, but the Arctic 

 coast northward is reached only by 

 chartered vessel or by special arrange- 

 ment with a trading or whaling ship or 

 with the government revenue cutter 

 which makes one trip per annum to 

 Point Barrow. 



