174 Biology in America 



animals which extend further down into the following zone, 

 the Hudsonian possessing so little that is characteristic that 

 it may perhaps best be included in the following or Cana- 

 dian, and the two grouped together as the Boreal zone. The 

 Canadian zone, which on San Francisco Mountain lies between 

 9,500 and 8,200 feet, is characterized by the Douglas spruce, 

 the limber pine, balsam fir and aspens. In the Boreal zone on 

 San Francisco Mountain occur a number of animals charac- 

 teristic of this zone in Canada and the mountains in the 



CANADIAN AND TRANSITION ZONE LANDSCAPE 



Fir forest of Canadian zone at left, open pine timber of transition 

 zone at right, showing effect of slope exposure. 



Courtesy of the U. S. Bureau of Biological Survey. 



United States. Some of the better known which inhabit it 

 throughout the United States and Canada are the elk, moose 

 and woodland caribou; the weasel, fisher, martin, mink, red 

 fox, wolverine, gray wolf; the marmot or wood chuck, por- 

 cupine, pika and snowshoe rabbit; most of the mountain 

 sheep and the Rocky Mountain goat, which is not a goat at 

 all, but a relative of the European chamois or antelope. 

 "The mammals of this sub-region (boreal) are largely of old 

 world origin, many of them coming in with the great immigra- 

 tions of the Pliocene and Pleistocene epochs, but there are 

 also native American elements and even one genus of South 



