STEPPES OP ASIA AND AMERICA 67 



(22 pounds), and are sufficiently numerous for it to be 

 worth while for the Mongolians to bring their cattle to 

 feed upon the pica's stores, and so dispense with the 

 trouble of storing fodder on their own account. Like 

 some other of the steppe animals, the picas are remark- 

 ably resistant to thirst, and can Hve in localities far 

 from water, where no rain nor dew occurs for months 

 at a time. 



As to the carnivores of the steppe, the tiger, though 

 usually regarded as a tropical animal, extends far 

 to the north, and occurs in steppe regions, perhaps in 

 more than one variety. When nobler game fail, it does 

 not disdain the rodents, notably the picas. The special 

 cat of the steppe is, however, the manul cat {Felis 

 manul), a beautiful animal with a bushy tail, about the 

 size of the common cat, and apparently aUied to the 

 wild cat of Europe, but, unhke it, a steppe animal. Its 

 main food consists of the steppe rodents, and also of 

 the ground-nesting birds. The steppe has also its 

 special fox, the corsac fox [Canis corsac), which also 

 feeds chiefly upon the steppe rodents. Here as else- 

 where the ubiquitous wolf also occurs. 



In regard to the birds of the steppe it is noticeable 

 that they tend to acquire swiftness in running, thus 

 showing parallelism with the mammals. This is 

 carried further in the birds of the warm deserts of the 

 world, where we have in ostrich, rhea, emu, &c., 

 examples of birds without any power of flight, but of 

 great fleetness of foot. The reason for this tendency is 

 possibly that the steppe or desert does not, like the 

 forest, offer safe places upon which to rest. As the 

 birds are exposed to danger so soon as they aUght, 

 which is necessarily upon the ground, fleetness is a great 

 advantage to them. 



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