xxii The Mammals of Colorado 
We have records of about ten species of mammals from this 
zone, and there should be more. Among the birds Ptarmigan, 
Brown-capped Leucosticte, and Pipit are practically re- 
stricted to it in the breeding season. 
The Hudsonian is, in Colorado, the region from about 
10,000 feet up to timber-line; it is the upper portion of the 
timbered belt of the mountains, characterized by Engelmann's 
spruce and white fir for the trees. The mammals most 
characteristic are the Pine Marten, Wolverene, Canada 
Lynx, and Snow-shoe Rabbit, though all these, the latter 
especially, may range into the zone below, the Canadian. 
The voles of the genus Phenacomys also range up into it. 
The Cony or Pika is found here, but also in the zones above 
and below. The Rocky Mountain Jay or Camp Bird is a 
very characteristic bird. 
The Canadian Zone is from 8,000 feet up to 10,000 feet, 
the lower part of the coniferous forests, with the upper part 
of the aspens. The animals named above under Hudsonian 
range in much of it, also two or three species of MicrotuSj 
and various long-tailed Shrews {Sorex and Neosorex), 
The Transition Zone in our State is from a little under 
6,000 up to 8,000 feet, part of the plains and all the foothill 
region. Here is found the yellow pine {Pinus scopulorum); 
the aspens first make their appearance in this zone; various 
species of cottonwoods are found in it, as also junipers 
("cedars") and pinons, and scrub-oaks and various other 
trees and shrubs. As its name would imply, it is intermediate 
or transitional between the zones above and below, and 
its fauna and flora are rather a mixture than specially char- 
acteristic, so that it is difficult to define it by any species. 
Among mammals Sciiirus aherti and its subspecies, Callo- 
spermophilus wortmani, Eutamias minimus and E. m. caryi^ 
and Peromyscus nasutus are confined to this zone, while Prairie 
Dogs, Black-tailed Jack Rabbits, Grasshopper Mice, Peromys- 
