454 LAND ANIMALS 



grain-eating birds, such as sand grouse and weaver birds, grind such 

 food by means of their muscular gizzard. These grass and grain feeders 

 constitute the key industry animals of the fauna of the steppes. The 

 food interrelationships of such a community are suggested in Fig. 120a 

 for the aspen parkland region in Manitoba. 19 



For the most part, the steppes proper are entirely treeless. Where 

 trees occur, they give a varied character to the formation. Thus at 

 Kilimanjaro, one may recognize fruit-tree steppes and acacia steppes, 

 to which the bush steppes join; the high campos of the Amazon are 

 comparable with fruit plantations. With the trees, the tree animals 

 come into the steppes, a part of the population which is really foreign 

 to the communities of open lands. Tree-nesting birds, which find 

 abundant food in the steppes, nest in large numbers in such trees. 

 There are weaver birds and other grain-eating birds in the African 

 steppe, ovenbirds with their giant nests in the Patagonian pampas, 20 

 and eagles, hawks, rooks, and others are closely packed into the forest 

 islands of the Siberian steppe. 21, 22 Of the orboreal mammals, it is 

 mainly the monkeys which follow the trees into the steppes, and only 

 for the night are they confined to the trees, the baboon in the Central 

 African steppe; the pampas monkey, Hapale penicillata, in the campos 

 of central Brazil. 23 Many mammals seek the scattered trees of the 

 steppe for their shade and take their noonday rest under them. 



The conditions during the favorable season are of less significance 

 for the organization and relationships of the animal population of the 

 grassland than the conditions of life during the least favorable season. 

 Whether there is a dry open winter or a snowy closed winter makes a 

 significant difference. The tropical and subtropical grasslands and 

 steppes have the former, the grasslands of the North Temperate Zone 

 have the latter. 



The dry season causes a reduction of life everywhere in grassland 

 and steppe ; the blazing heat of the sun is as detrimental as frost. Many 

 insects and reptiles and all snails and amphibians aestivate; even many 

 mammals pass the unfavorable season in this manner, like the African 

 aardvark. Some animal life remains active. Termites and ants survive 

 the heat and drought, finding enough moisture in the deeper parts of 

 their subterranean nests. 24 Other insects and spiders may be found 

 under stones; small and dull-colored locusts occur under dried brush. 

 A number of species of reptiles remain active. The number of birds 

 is somewhat reduced, but this group is not absent, and there are still 

 more sorts of mammals than birds. The masses of dry grass, especially 

 the seeds, contain a large amount of food for both. 



The chief problem for birds and mammals is the water supply. 



