INTRODUCTIOX xxxv 



The Canadian Zone comprises " the southern or lower part of the 

 great transcontinental coniferous forest." It is the zone of firs, 

 spruces, and white pines, which on Mt. Shasta are represented by 

 the Shasta fir and the silver pine. One of its characteristic animals 

 is the mountain heaver, and it has also the porcupine, pine squirrel, 

 bear, wild cat, wolf, and other mammals. It is the home of the 

 crossbill, J incoln sparrow, and Arctic three-toed woodpecker, and 

 frequented by birds found in the Hudsouian zone, such as the sooty 

 grouse, rufous hummingbird, siskin, j uncos, warblers, kinglets, and 

 solitaire, together with a number found also in the next lower zone 

 (the Transition), such as the white-headed, hairy, and pileated 

 woodpeckers, uighthawk, olive-sided, Hammond, Wright, and west- 

 ern flycatchers, Steller jay, Louisiana tanager, Macgillivray war- 

 bler, and robin. 



TJie Transition Zone, in which northern and southern elements of 

 flora and fauna often overlap, is characterized in the west by the 

 yellow pine {Finns ponderosa), several species of oaks and manza- 

 nita. together with buck brush and sage brush. Some of the char- 

 acteristic mammals are the big gray pine squirrel, the gray fox, 

 and various species of chipmunks, spermophilcs. and pocket go 

 phers. Among birds there are the western wood pewee, Gairdner 

 woodpecker, Lewis woodpecker, California pygmy owl, green-tailed 

 towhee, pygmy nuthatch, red-breasted sapsucker, and Brewer spar- 

 row, mixed with many species from the Upper Sonoran, the zone 

 below, such as the California jay, valley quail, California wood 

 pecker, and spurred towhee. 



The Upper Sonoran Zone of the west is characterized by junipers, 

 pifion, and various oaks, jack rabbits, cottontails, five-toed kangaroo 

 rats, and several species of wood rats, the canyon wren, western lark 

 sparrow. California chewink, and California bush-tit, while many 

 Transition zone species also occur. 



The Lower Sonoran Zone, coming iie.xt above the Tropical zone, 

 is the zone of the hot valleys, where live-oaks, mes(iultes, and creo- 

 sote bushes abound, and the characteristic mammals and birds an- 

 the four-toed kangaroo rat, cotton rat, and spottctl skunk, the 

 mockingbird, nonpareil, verdin. pyrrhuloxia, road runner, caracara, 

 white-necked raven, i)liain()i)('pla, and scaled (juail. 



of Mt. Sliasta ; " Sorth Americdu Ftnni/i, No. 3, " UcHults of a BioloRioal Survey of San 

 Francisco Mountain ReRion and Desert of the Little Colorado; " " The Geographic Dis- 

 tribution of Life in North America, witli Si>ecial Reference to the Munmialiu," Pun: 

 Biol. Soc. Wash. vii. April, IS'JJ, 1-G4. 



