COMMUNITIES IN DRY, OPEN LANDS 463 



many of them have even given up flight and become cursorial ground 

 birds. They are better able than other animals to avoid temporarily 

 unfavorable conditions; and for that reason, there are only a few 

 endemic birds of such regions. On the other hand, the conditions for 

 the establishment of their nests is less favorable in the open lands; 

 most birds must breed on the ground, even eagles or storks which else- 

 where seek unapproachable nest sites. They are most praecocial, espe- 

 cially the larger forms, and more especially the ground birds proper; 

 but there are also altricial birds among those nesting on the ground, 

 such as larks, buntings, rosy starling, or birds of prey. 



Grassland fires present scenes that are constantly repeated in the 

 African steppes, 61 in the prairies of North America, in the llanos of the 

 Guianas, 62 in the Asiatic steppes, 63 and in the grassy wildernesses of 

 New Caledonia. 64 When the dry grass begins to burn, the rising clouds 

 of smoke are the signal for many birds to hurry to the scene of the 

 fire, for the flames drive ahead of them all creatures which cannot 

 creep into the ground. Hunters of creeping and burrowing animals 

 among the bird world such as marabous and storks run about snapping 

 up their prey before the fire; hawks fly over the fire, while insect- 

 eating swallows, flycatchers, and shrikes follow their prey almost into 

 the flames. 



Of the mammals, the herbivores naturally predominate in the grass 

 areas. The rodents surpass all others in number of species and indi- 

 viduals. In Tripoli 65 two-thirds, in the Russian steppes 66 three-fourths, 

 in California three-fifths, of the mammals (121 out of 201) are ro- 

 dents. 67 Because of their small size, fertility, and resistance to drought, 

 they have the advantage over other mammals. They are mostly fos- 

 sorial in habits, and the young are protected in nests. They form a prin- 

 cipal food for many predatory animals: eagles, hawks, owls, wolves, 

 foxes, certain cats, and others; but their fertility balances all losses. 

 Ungulates join them as grass-eaters according to the location: wild 

 horses, asses, zebras, especially antelopes, giraffes, bison, pampas deer, 

 camels, and guanacos, and there are, in addition, the elephant and 

 rhinoceros in the African steppes. With these larger animals, the young 

 must follow the mother soon after birth. While the non-rodents bulk 

 larger as individual units, yet the amount of food consumed by rodents 

 may run as high as 75% of that available. Next to the rodents, the 

 ruminants such as antelopes, cattle, deer, and camelids are the most 

 abundant. Among them grass is gulped down, partially fermented in 

 the stomach, and regurgitated later for more thorough mastication. 

 The large predatory animals — lions, leopards, hunting dogs, and wolves 



