NORTH AMERICA AND THE WEST INDIES 349 



increase of the herd, tend to add to the living resources of the 

 human population in the region. The combined herds have so 

 increased that in 1934 the total number of buffalo in the park 

 was estimated at about 8,500 (Anderson, 1937, p. 103). 



Outside and to the northwest of the park there is said to be 

 a small band of 20 to 30 buffalo in a place known locally as the 

 Buffalo Mountains on the South Nahanni River, and it is not 

 impossible that these may help to perpetuate the woodland 

 stock, since its requirements are slightly different from those 

 of the Plains bison (notes of Dr. Harper from manuscript 

 report of H. M. Snyder) . Thus, while the wood bison may be 

 considered as no longer in danger of extermination by man, it 

 remains to be seen whether its type will disappear through 

 interbreeding with the imported Plains stock. 



THE BIGHORN, OR MOUNTAIN SHEEP 



Of all American game animals, probably the bighorn offers 

 the greatest thrill to the sportsman. A dweller in open moun- 

 tainous country, keenly alert to the least danger, with excep- 

 tional eyesight and hearing, it is the most difficult to approach 

 of all American mammals, while its magnificent horns make a 

 fine trophy for the successful hunter. The American members 

 of this genus appear to have come in from Asia at a time when 

 it was possible to cross from the northeastern extremity of 

 that continent to Alaska, probably during the Pleistocene 

 period. Thence they have spread southward through the 

 western mountain chains to northern Mexico and eastward to 

 the Dakotas. At the present time zoologists recognize two 

 American species, the white, or DalPs, sheep in the northwest 

 and the mountain sheep, or bighorn, from British Columbia 

 south. Several races of each have been named at various 

 times, but only recently has a comprehensive study of the 

 group been made (Cowan, 1940), the results of which have 

 been followed here. 



WHITE SHEEP; BALL'S SHEEP 



OVIS DALLI DALLI Nelson 



Ovis montana dalli Nelson, Proc. U. S. Nat. Mus., vol. 7, p. 13, June 3, 1884 (mountains 

 west of Fort Reliance, Alaska, on the divide between Tanana and Yukon Rivers). 



FIGS.: Hornaday, 1901, figs, on pp. 83, 86, and pis. facing pp. 86, 92, 94; Nelson, 1916, 

 p. 450, lower fig. (col.); Sheldon, 1930, pis. facing pp. 78, 79 (photographs). 



